User-Centered Development and Patient Acceptability Testing of a Health-Coaching Intervention to Enhance Cancer Survivorship Follow-up in Primary Care

We describe an iterative three-phase approach used to develop a cancer survivorship health-coaching intervention to guide self-management and follow-up care for post-treatment breast, colorectal, and prostate cancer survivors. Informed by theory (e.g., Cognitive-Social Health Information Processing Model (C-SHIP)), relevant literature, and clinical guidelines, we engaged in a user-centered design process. In phase I, we conducted depth interviews with survivors of breast (n = 34), prostate (n = 4), and colorectal (n = 6) cancers to develop a health coaching prototype. In phase II, we utilized user-testing interviews (n = 9) to test and refine the health coaching prototype. For both phases, we used a template analysis independently coding each interview. In phase I, majority (n = 34, 81%) of survivors were positive about the utility of health coaching. Among these survivors (n = 34), the top areas of identified need were emotional support (44%), general health information (35.3%), changes in diet and exercise (29.3%), accountability and motivation (23.5%), and information about treatment effects (17.7%). The prototype was developed and user-tested and refined in phase III to address the following concerns: (1) the amount of time for calls, (2) density of reading materials, (3) clarity about health coaches' role, (4) customization. Collectively, this resulted in the development of the Extended Cancer Educational for Long-Term Cancer Survivors health-coaching (EXCELS_HC) program, which represents the first cancer survivorship follow-up program to support follow-up care designed-for-dissemination in primary care settings. EXCELS_HC is being tested in a clinical efficacy trial. Future research will focus on program refinement and testing for effectiveness in primary care.

Correlates of Information Seeking Behaviors and Experiences Among Adult Cancer Survivors in the USA

Understanding information seeking behaviors and experiences is essential for designing educational and supportive interventions to promote survivor's self-management post treatment. This study examined health and cancer information seeking, use of internet to find cancer information, and information seeking experiences among breast, colorectal, and prostate cancer survivors. Nationally representative data collected in 2017-2018 from 2 cycles of the Health Information National Trends Survey (HINTS 5, cycles 1 and 2 were merged with combined replicate weights using the jackknife replication method (n = 373). Regression analysis for three information seeking behaviors (i.e., health information, cancer information, and internet for cancer information) were modeled, including sociodemographic and clinical factors as predictors. In addition, separate regression analysis predicted three experiences of information seeking (effort, quality, and hard to understand) with sociodemographic and clinical factors. A majority of survivors (84.7%) sought health information. Factors significantly associated with seeking health information were gender (p = 0.024), education (p = 0.0021), and income (p = 0.018). Only 38% of survivors used the internet to seek cancer-related information. The only factor significantly associated with using the internet to seek cancer-related information was time since diagnosis (p = 0.0002). The factor significantly associated with difficulty understanding information was annual household income (p = 0.026). This study fills an important gap by identifying sociodemographic and cancer-related factors associated with information seeking behaviors and experiences. These findings highlight a need to tailor information for low socioeconomic status survivors to account for the lack of skills, resources, and motivation to seek information about health and cancer related topics independently.

Demographic and psychosocial factors associated with limited health literacy in a community-based sample of older Black Americans

OBJECTIVES

Individuals with limited health literacy often experience suboptimal health outcomes. This study examined the frequency of limited health literacy and demographic and psychosocial factors associated with limited health literacy in a sample of older Black Americans.

METHODS

Participants (n = 330) enrolled in a community-based intervention to promote colorectal cancer (CRC) screening completed baseline surveys assessing health literacy with the Rapid Estimate of Adult Literacy in Medicine, Revised (REALM-R) test, CRC awareness, cancer fatalism, Preventive Health Model (PHM) constructs, and demographics.

RESULTS

Approximately 52% of participants had limited health literacy, the REALM-R score was 5.4 (SD = 2.7). Univariable correlates of limited health literacy were gender, employment, income, prior screening, cancer fatalism, CRC awareness, and PHM constructs (religious beliefs, salience/coherence, perceived susceptibility). Multivariable correlates of limited health literacy were male gender (OR = 2.3, CI = 1.4-3.8), unable to work (OR = 2.8, CI = 1.3-6.1), lower household income (OR = 3.0, CI = 1.6, 5.5), and higher PHM religious beliefs (OR = 1.1, CI = 1.0-1.2).

CONCLUSION

Limited health literacy was associated with multiple complex factors. Interventions should incorporate patient health literacy and low-literacy materials that can be delivered through multiple channels.

PRACTICE IMPLICATIONS

Future studies are needed to understand the role of health literacy in an individual's health behavior and the provision of effective healthcare.

Development and usability testing of the e-EXCELS tool to guide cancer survivorship follow-up care

OBJECTIVE

The aim of this study is to describe a user-centered (e.g., cancer survivors and clinicians) development process of an eHealth tool designed to facilitate self-management of cancer survivorship follow-up care.

METHODS

Guided by Cognitive-Social Health Information Processing (C-SHIP) model and informed by core self-management skills, we engaged in a user-centered design process. In phase I, we conducted in-depth interviews with survivors of breast (n = 33), prostate (n = 4), and colorectal (n = 6) cancers, and (n = 9) primary care providers to develop content and design of the web tool. Phase II utilized iterative user testing interviews (n = 9) to test the web-based tool prototype. Data from both phases were independently coded using a template/content analytic approach.

RESULTS

The top 5 functions identified in phase I for the web-based platform included: (a) educational materials to learn and prepare for health encounters (80%); (b) questions for health providers (74%); (c) ability to track contact information of providers (67%); (d) provide general information (64%); and, (e) support information (62%). Users of the prototype reported patient burden, tool fatigue, introduction timing of the tool, relevance, and security/privacy as concerns in phase II.

CONCLUSIONS

This study demonstrates the value of using a theoretically informed and user-centered design process to develop relevant and patient-centered eHealth resources to support cancer survivorship. A larger study is needed to establish the efficacy of this eHealth tool as an intervention to improve adherence to follow-up care guidelines.

Rationale and design of extended cancer education for longer term survivors (EXCELS): a randomized control trial of 'high touch' vs. 'high tech' cancer survivorship self-management tools in primary care

Background

Breast, colorectal, and prostate cancer survivors are at increased risk for late and long-term effects post-treatment. The post-treatment phase of care is often poorly coordinated and survivors navigate follow-up care with minimal information or guidance from their healthcare team. This manuscript describes the Extended Cancer Education for Longer-term Survivors (EXCELS) in Primary Care protocol. EXCELS is a randomized controlled trial to test the efficacy of patient-level self-management educational strategies on adherence to preventative health service use and cancer survivorship follow-up guidelines.

Methods

The EXCELS trial compares four conditions: (1) EXCELS-website (e.g., a mobile-optimized technology platform); (2) EXCELS-health coaching; (3) EXCELS-website and health coaching; and (4) a print booklet. Approximately 480 breast, colorectal, and prostate survivors will be recruited through the New Jersey Primary Care Research Network (NJPCRN) and New Jersey State Cancer Registry (NJSCR). Eligible survivors (diagnosed stages 1–3) must have completed active treatment, access to a phone and a computer, smartphone or tablet with internet access, and be able to speak and read English. Patient assessments occur at baseline, 6, 12, and 18 months. The primary outcomes are increased engagement in preventive health services and monitoring for cancer recurrence and treatment-related late effects.

Discussion

The EXCELS trial is the first to test cancer survivorship educational self-management interventions for cancer survivors in a primary care context. Findings from this trial will inform successful implementation and engagement strategies for longer-term, post-treatment cancer survivors managed in primary care settings.

Trial registration

Registered August 1, 2017 at ClinicalTrials.gov, trial # NCT03233555.

Examining the Durability of Colorectal Cancer Screening Awareness and Health Beliefs Among Medically Underserved Patients: Baseline to 12 months Post-Intervention

The current study examines changes in awareness and health beliefs from baseline to 12 months post-intervention following receipt of one of two colorectal cancer (CRC) educational interventions that aimed to promote CRC screening among a racially and ethnically diverse and medically underserved population. Participants (N = 270) were enrolled in a randomized controlled trial to increase CRC screening and completed both baseline and 12-month follow-up assessments. Participants were aged 50-75, at average CRC risk, not up-to-date with CRC screening guidelines, and receiving care at one of three community-based clinics. Participants were randomized to receive either a targeted, low-literacy intervention informed by the Preventive Health Model [PHM] (photonovella and DVD plus fecal immunochemical test [FIT]) or a non-targeted intervention (standard educational brochure plus FIT). Changes in CRC awareness and health beliefs from baseline to 12 months were examined both within and between intervention groups using Student's t tests. Participants in both intervention conditions demonstrated an increase in CRC awareness, PHM social influence, and trust in the healthcare system (all p's < .0001), with no significant between-group differences. Among those receiving the targeted intervention, there also was an increase in PHM salience (p < .05). Among individuals receiving the non-targeted intervention, there was an increase in PHM response efficacy (p < .01) and PHM self-efficacy (p < .0001). Both CRC screening interventions promoted positive changes in awareness and several health beliefs from baseline to 12 months, suggesting important benefits of CRC education. Regardless of whether education was targeted or non-targeted, providing CRC screening education successfully promoted durable changes in awareness and health beliefs.

Patient and Physician Factors Associated with Undisclosed Prostate Cancer Screening in a Sample of Predominantly Immigrant Black Men

Medical guidelines do not recommend prostate cancer screening, particularly without informed and shared decision making. This study investigates undisclosed opportunistic screening using prostate specific antigen (PSA) testing in black immigrant and African American men. Participants (N = 142) were insured urban men, 45- to 70-years old. Patients' reports of testing were compared with medical claims to assess undisclosed PSA testing. Most (94.4 %) men preferred to share in screening decisions, but few (46.5 %) were aware PSA testing was performed. Four factors predicted being unaware of testing: low formal education, low knowledge about prostate cancer, no intention to screen, and no physician recommendation (all p's < .05). Undisclosed PSA testing was common. Both patient and provider factors increased risk of being uninformed about prostate cancer screening. Interventions combining patient education and physician engagement in shared decision making may better align practice with current prostate cancer screening guidelines.

Health Literacy among Medically Underserved: The Role of Demographic Factors, Social Influence, and Religious Beliefs

The current study examined the sociodemographic and psychosocial variables that predicted being at risk for low health literacy among a population of racially and ethnically diverse patients accessing primary care services at community-based clinics. Participants (N = 416) were aged 50-75 years, currently not up-to-date with colorectal cancer (CRC) screening, at average CRC risk, and enrolled in a randomized controlled trial (RCT) aimed at promoting CRC screening. Participants completed a baseline interview that assessed health literacy as measured by Rapid Estimate of Adult Literacy in Medicine-Revised, sociodemographic factors, and psychosocial variables (e.g., health beliefs) prior to randomization and receipt of an intervention. Thirty-six percent of the participants were found to be at risk for low health literacy. Sociodemographic and psychosocial variables were assessed as predictors of being at risk for low health literacy using logistic regression. In the final model, predictors were male gender, being from a racial/ethnic minority group, being unable to work, having higher social influence scores, and having higher religious belief scores. These findings suggest several patient characteristics that may be associated with low health literacy, and highlight the importance of supporting all patients through simplified and clear communications and information to improve understanding of CRC screening information.

Primary care physicians experiences of caring for cancer survivors: Toward developing a primary care-responsive cancer survivorship research agenda

97

Background: Understanding of the ecology of primary care can inform efforts that aim to build primary care capacity to address cancer survivorship issues. This study describes the experiences of primary care physicians (PCPs) delivering care to cancer survivors. Methods: Semi-structured in-depth interviews were conducted with PCPs (n=30) across two NCI-funded studies of cancer survivorship in primary care. PCPs were recruited from primary care practices enrolled in a qualitative case study of cancer survivorship in patient centered medical homes (R01 CA176545; n=21) and from a sample recruited for the formative development of a primary care mHealth and health coaching interventions for cancer survivors (R01 CA176838; n=9). Interviews averaged 30 minutes, were audio-recorded and transcribed verbatim. A multi-step immersion/crystallization approach was used to identify emergent themes using Atlas.ti. Results: PCPs stated that their role in cancer survivorship care varies widely and is often shaped by patient characteristics. These characteristics include: patient expectations of the PCPs role; the patient’s ability to provide clinical details about their cancer and its treatment; and the status of patient relationship with cancer treatment team. PCPs described having incomplete information and recounted experiences of cancer survivors presenting for visits motivated by fear of disease recurrence. PCPs described the tensions around having to make decisions about further additional testing versus offering support about recurrence of fears with incomplete clinical information. PCPs also expressed a need for basic clinical information and surveillance plans to be integrated into existing systems of care (e.g. electronic medical record systems and registries), citing immunization schedules as a potential model. Conclusions: The lack of clinical information to inform cancer survivors’ care remains a critical challenge to PCPs. Survivorship care plans are a proposed strategy to rectify informational deficits; however, further evaluation of how effectively care plans integrate into primary care systems and processes are needed.

Abstract A63: Changes in health beliefs among medically-underserved patients enrolled in a community-based randomized controlled trial to promote colorectal cancer screening

Marked health disparities exist in colorectal cancer (CRC) screening, incidence, and mortality among medically-underserved communities. Literature suggests certain health beliefs (e.g., perceived risk) may be related to screening behavior. This study examined changes in CRC health beliefs following receipt of one of two educational interventions aimed at promoting CRC screening uptake among a medically-underserved population. We compared changes in CRC health beliefs at baseline and 12 months later both within and between the two intervention groups.

Enrolled participants were aged 50-75, at average CRC risk, not up-to-date with CRC screening guidelines, enrolled in a randomized controlled trial to increase CRC screening that was conducted at community clinics in the Tampa Bay area, and completed both the baseline and 12 month follow-up assessments. Participants were randomized to receive either a culturally-targeted photonovella and DVD plus fecal immunochemical test (FIT) intervention (titled Colorectal Cancer Awareness, Research, Education and Screening, or CARES, intervention group condition) or a Centers for Disease Control and Prevention (CDC) standard educational brochure plus FIT intervention (comparison group condition). At both time points, participants completed a questionnaire that included multiple health-related beliefs including Preventive Health Model (PHM) constructs (i.e., perceived susceptibility, perceived salience, self-efficacy, response efficacy, cancer worry, social influence, and religious beliefs), CRC awareness, decisional conflict regarding CRC screening, cancer fatalism, trust in the healthcare system, and perceived discrimination. Changes in health belief scores and group differences in change were examined using Student's t-tests.

The majority of participants (n=270) were: female (58%); white (67%) or black (26%); insured (59%) including county health insurance; had a household income &lt;$10,000 (65%); and had a high school education (35%) or more than high school education (41%). In both intervention conditions, there was an increase in CRC awareness, PHM social influence, and trust in the healthcare system (all p's&lt;.0001). In the CARES intervention group, there also was an increase in PHM salience (p&lt;.05). Among individuals in the comparison group, there was an increase in PHM response efficacy (p&lt;.01) and PHM self-efficacy (p&lt;.0001). There were no significant between-group differences on any of the health belief change scores.

Both CRC screening interventions promoted positive changes in multiple health beliefs from baseline to 12 months which suggests clear benefits of educational interventions. The interventions had common positive effects (i.e., CRC awareness, PHM social influence, and trust in the healthcare system), but also unique effects on PHM salience (CARES condition) and PHM self-efficacy and PHM response efficacy (comparison condition). However, between-group intervention comparisons were not significant suggesting that both educational interventions are beneficial. Given that individuals in both intervention groups were provided with access to CRC screening via FIT kit, future analyses will examine whether changes in health beliefs were associated with higher CRC screening uptake.

Citation Format: Shannon M. Christy, Steven K. Sutton, Enmanuel Chavarria, Stacy N. Davis, Rania Abdulla, Gwendolyn P. Quinn, Susan T. Vadaparampil, Chitra Ravindra, Ida Schultz, Richard Roetzheim, David Shibata, Cathy D. Meade, Clement K. Gwede. Changes in health beliefs among medically-underserved patients enrolled in a community-based randomized controlled trial to promote colorectal cancer screening. [abstract]. In: Proceedings of the Ninth AACR Conference on the Science of Cancer Health Disparities in Racial/Ethnic Minorities and the Medically Underserved; 2016 Sep 25-28; Fort Lauderdale, FL. Philadelphia (PA): AACR; Cancer Epidemiol Biomarkers Prev 2017;26(2 Suppl):Abstract nr A63.

A randomized controlled trial of a multicomponent, targeted, low-literacy educational intervention compared with a nontargeted intervention to boost colorectal cancer screening with fecal immunochemical testing in community clinics

BACKGROUND

The objective of the current study was to improve colorectal cancer (CRC) screening uptake with the fecal immunochemical test (FIT). The current study investigated the differential impact of a multicomponent, targeted, low-literacy educational intervention compared with a standard, nontargeted educational intervention.

METHODS

Patients aged 50 to 75 years who were of average CRC risk and not up-to-date with CRC screening were recruited from either a federally qualified health center or a primary care community health clinic. Patients were randomized to the intervention condition (targeted photonovella booklet/DVD plus FIT kit) or comparison condition (standard Centers for Disease Control and Prevention brochure plus FIT kit). The main outcome was screening with FIT within 180 days of delivery of the intervention.

RESULTS

Of the 416 participants, 54% were female; the participants were racially and ethnically diverse (66% white, 10% Hispanic, and 28% African American), predominantly of low income, and insured (the majority had county health insurance). Overall, the FIT completion rate was 81%, with 78.1% of participants in the intervention versus 83.5% of those in the comparison condition completing FIT (P =  .17). In multivariate analysis, having health insurance was found to be the primary factor predicting a lack of FIT screening (adjusted odds ratio, 2.10; 95% confidence interval, 1.04-4.26 [P =  .04]).

CONCLUSIONS

The multicomponent, targeted, low-literacy materials were not found to be significantly different or more effective in increasing FIT uptake compared with the nontargeted materials. Provision of a FIT test plus education may provide a key impetus to improve the completion of CRC screening. The type of educational material (targeted vs nontargeted) may matter less. The findings of the current study provide a unique opportunity for clinics to adopt FIT and to choose the type of patient education materials based on clinic, provider, and patient preferences. Cancer 2017;123:1390-1400. © 2016 American Cancer Society.

A community-based trial of educational interventions with fecal immunochemical tests for colorectal cancer screening uptake among blacks in community settings

BACKGROUND

Intervention studies among individuals in diverse community settings are needed to reduce health disparities in colorectal cancer (CRC) screening and mortality rates. The current study compared the efficacy of 2 intervention conditions promoting CRC screening among black individuals.

METHODS

Black individuals ages 50 to 75 years (N = 330) were recruited in community settings in 4 Tampa Bay counties. After obtaining consent and conducting a baseline interview to assess sociodemographic and health-related variables, participants received either a culturally targeted CRC photonovella booklet plus a fecal immunochemical test (FIT) kit or a standard CRC screening brochure plus an FIT kit. The primary outcome was FIT kit screening uptake.

RESULTS

FIT screening uptake at 6 months was 86.7% overall (90.3% in the brochure group and 81.9% in the photonovella group). Controlling for baseline between-group differences, there was no influence of intervention on FIT kit uptake (P = .756). Significant predictors of not returning an FIT kit included being unable to work (P = .010), having higher religious belief scores (P = .015), and living farther from the cancer center (P = .015).

CONCLUSIONS

Providing FIT kits and educational print materials to black individuals in community settings resulted in high rates of CRC screening. The study also identified subgroups of participants who were less likely to return an FIT kit and provides insight for future interventions. Cancer 2016;122:3288-3296. © 2016 American Cancer Society.

Lessons Learned from Implementing a Prostate Cancer Risk Assessment Program for Underserved High-Risk Men in the Community: the Prostate REACH Project

Prostate cancer disproportionately affects Black men, who may also encounter barriers to participation in prostate cancer risk assessment. The Prostate Risk, Education and Assessment in the Community with Help (REACH) project was a community-based extension of a comprehensive prostate cancer risk assessment program at a comprehensive cancer center. The goals of the REACH project were the following: (1) establish a community prostate cancer risk assessment clinic, (2) conduct targeted recruitment, and (3) provide navigation services including follow-up for uninsured men. Key implementation steps included the following: (1) choosing a clinic site, (2) establishing patient access procedures, (3) establishing navigator services, (4) developing subsidy fund use guidelines, and (5) designing recruitment and promotion. Through community-based promotion, 64 men inquired about the program and 26 (41 %) participated. Of those screened, 46 % had abnormal results, and 2 men were diagnosed with prostate cancer. Here, we describe a unique demonstration project to implement a comprehensive prostate cancer risk assessment program in an underserved Black community and describe successes and challenges to inform future efforts to promote access to underserved men.

Perceptions of Prostate Cancer Screening Controversy and Informed Decision Making: Implications for Development of a Targeted Decision Aid for Unaffected Male First-Degree Relatives

PURPOSE

First-degree relatives (FDRs) of prostate cancer (PC) patients should consider multiple concurrent personal risk factors when engaging in informed decision making (IDM) about PC screening. This study assessed perceptions of IDM recommendations and risk-appropriate strategies for IDM among FDRs of varied race/ethnicity.

DESIGN

A cross-sectional, qualitative study design was used.

SETTING

Study setting was a cancer center in southwest Florida.

PARTICIPANTS

The study comprised 44 participants (24 PC patients and 20 unaffected FDRs).

METHOD

Focus groups and individual interviews were conducted and analyzed using content analysis and constant comparison methods.

RESULTS

Patients and FDRs found the PC screening debate and IDM recommendations to be complex and counterintuitive. They overwhelmingly believed screening saves lives and does not have associated harms. There was a strongly expressed need to improve communication between patients and FDRs. A single decision aid that addresses the needs of all FDRs, rather than one separating by race/ethnicity, was recommended as sufficient by study participants. These perspectives guided the development of an innovative decision aid that deconstructs the screening controversy and IDM processes into simpler concepts and provides step-by-step strategies for FDRs to engage in IDM.

CONCLUSION

Implementing IDM among FDRs is challenging because the IDM paradigm departs from historical messages promoting routine screening. These contradictions should be recognized and addressed for men to participate effectively in IDM. A randomized pilot study evaluating outcomes of the resulting decision aid is underway.

Patients' perceptions of colorectal cancer screening tests and preparatory education in federally qualified health centers

This study explored federally qualified health center (FQHC) patients' perceptions about colorectal cancer screening (CRCS) tests, including immunochemical fecal occult blood tests (iFOBT), as well as preferences for receiving in-clinic education about CRCS. Eight mixed gender focus groups were conducted with 53 patients. Findings centered on three thematic factors: (1) motivators and impediments to CRCS, (2) test-specific preferences and receptivity to iFOBTs, and (3) preferences for entertaining and engaging plain language materials. Results informed the development of educational priming materials to increase CRCS using iFOBT in FQHCs.

Informed decision making among first-degree relatives of prostate cancer survivors: a pilot randomized trial

BACKGROUND

First degree relatives (FDRs) of men diagnosed with prostate cancer (PCa) are at increased risk for developing the disease, due in part to multiple concurrent risk factors. There is a lack of innovative targeted decision aids to help FDRs make an informed decision about whether or not to undergo PCa screening.

PURPOSE

This randomized pilot trial evaluated the efficacy of a targeted PCa screening decision aid in unaffected FDRs of PCa survivors.

METHODS

Seventy-eight Black and White FDRs were randomized to one of two decision aid groups; 39 to a FDR-targeted decision aid and 39 to a general decision aid. The targeted decision aid group received a general PCa decision aid booklet plus a newly developed decision aid DVD targeted specifically for FDRs. PCa screening decision outcomes included knowledge, decisional conflict, distress, and satisfaction with screening decision. Outcomes were assessed at baseline and 4 weeks after baseline.

RESULTS

There were no differences by intervention group for knowledge, decisional conflict, distress, or satisfaction with screening decision (p>0.05). However, men in both groups had significant increases in knowledge and decreases in decisional conflict (p<0.001). These changes were most pronounced (p<0.05) for younger men compared to older men.

CONCLUSION

Results suggest that general and targeted information can play an important role in increasing knowledge and decreasing decisional conflict among FDRs. Additional research is needed to identify subgroups of men who benefit the most and better understand the outcomes of a screening decision aid among diverse samples of FDRs.

Use and taxonomy of social media in cancer-related research: a systematic review

Little is known about how social media are used in cancer care. We conducted a systematic review of the use and taxonomy of social media in cancer-related studies, in PubMed, Web of Knowledge, CINAHL, and Google Scholar. We located 1350 articles published through October 2013; 69 met study inclusion criteria. Early research (1996-2007) was predominantly descriptive studies of online forums. Later, researchers began analyzing blogs, videos shared on YouTube, and social networking sites. Most studies (n = 62) were descriptive, and only 7 reported intervention studies published since 2010. Future research should include more intervention studies to determine how social media can influence behavior, and more empirical research is needed on how social media may be used to reduce health disparities.

Making it work: health care provider perspectives on strategies to increase colorectal cancer screening in federally qualified health centers

Colorectal cancer screening (CRCS) rates are low among men and women who seek health care at federally qualified health centers (FQHCs). This study explores health care providers' perspectives about their patient's motivators and impediments to CRCS and receptivity to preparatory education. A mixed methods design consisting of in-depth interviews, focus groups, and a short survey is used in this study. The participants of this study are 17 health care providers practicing in FQHCs in the Tampa Bay area. Test-specific patient impediments and motivations were identified including fear of abnormal findings, importance of offering less invasive fecal occult blood tests, and need for patient-centered test-specific educational materials in clinics. Opportunities to improve provider practices were identified including providers' reliance on patients' report of symptoms as a cue to recommend CRCS and overemphasis of clinic-based guaiac stool tests. This study adds to the literature on CRCS test-specific motivators and impediments. Providers offered unique approaches for motivating patients to follow through with recommended CRCS and were receptive to in-clinic patient education. Findings readily inform the design of educational materials and interventions to increase CRCS in FQHCs.

Sulfonylureas and meglitinides: historical and contemporary issues

Insulin secretagogue therapy is commonly used in clinical practice. These agents may be utilized as first, second-line or adjunct therapy behind metformin for treatment of type 2 diabetes mellitus. Sulfonylureas and meglitinides are effective treatments, but cumulative data over decades of research raise concerns regarding universal prescribing. The role of insulin secretagogue therapy in β-cell failure, blunting of ischemic pre-conditioning, the incidence of hypoglycemia - specifically in at-risk populations, modest weight gain and the unproven link to cancer are discussed. Ultimately, many of the concerns appear to be agent and not class-specific with glibenclamide fairing the worst amongst all of the agents discussed.

Abstract B6: Region Five GMaP/BMaP Network: Preliminary findings from the comprehensive needs assessment biospecimen facility survey

Objective: The Region Five GMaP/BMaP Network is a regional partnership representing 18 NCI funded institutions charged with the implementation of a comprehensive needs assessment (CNAT). This presentation focuses on preliminary findings from the Biospecimen Facility Survey.

Methods: The CNAT consisted of a mixed methods approach utilizing four instruments: A principal Investigator Survey and PI Interview and a Biospecimen Facility Survey and Interview. The surveys were conducted online during the months of March/ April 2011. Interviews will be conducted in July. The goal of the biospecimen facility survey which is the focus of this abstract is to assess minority biospecimen collection, biobanking practices, education, and outreach initiatives. The biospecimen survey consisted of 14 distinct questions, with affiliated subset questions, across five areas. These questions captured details from the institutions’ core facilities and inventory human specimens that were available for research. The survey was completed online by 10 biospecimen facility administrators.

Results: Preliminary findings consistently reported disparities in biospecimen collection among minority populations. Eight out of ten facilities reported the types of cancer and racial and ethnic groups from whom they collected specimens. Upon close review of the data, gaps in specimens collected for populations with a high burden of cancer were commonly identified. Seven facilities reported having collected specimen from 116,417 White patients vs. 12,592 Non-White (minority) patients’ and 1648 Hispanic patients’. Tissue (diseased and healthy) was most commonly collected and bodily fluids were least commonly collected.

While 40% of the biospecimen facilities have collaborated on biospecimen education efforts, we have learned that 60% of these facilities have collaborated on projects that collect specimens for the study of health disparities. The data mirrors similar findings from the PI survey; over half of our PIs are involved in biospecimen education and minority collection efforts.

In reference to bioinformatics and electronic data systems we found that 100% of the Region Five facilities currently use electronic annotation systems for biospecimen collection. However, there is a wide range of data systems/platforms used across the institutions which raise issues of compatibility. Along with this, we have found that 94% of specimens collected by our facilities have associated pathology data available.

Biospecimen facility administrators identified barriers which limit them from collaborating in collection programs. However, they also indicated a high desire to collaborate.

Conclusions: There is a need to focus on minority biospecimen collection efforts and address the gaps in how race and ethnicity and subtypes of biospecimens are collected across our institutions. Region Five is exploring ways to share instruments and methodologies used to collect race and ethnicity and develop strategies to standardize patient information collected. We anticipate implementing Cancer 101 and 102 education and training on research participation, biospecimen donation/biobanking and genetics across our institutions. In addition, there are opportunities for collaboration among principal investigators and biospecimen facilities around minority specimen collection efforts.

Citation Information: Cancer Epidemiol Biomarkers Prev 2011;20(10 Suppl):B6.

Abstract B13: Lessons learned from implementing a prostate cancer risk assessment program for underserved high-risk men: The Prostate REACH Project

Background: Prostate cancer disproportionately affects Black men. Black men are 60% more likely to be diagnosed with prostate cancer and 2.4 times more likely to die from prostate cancer compared to White men. Therefore, prostate cancer risk assessment programs are important to assess risk, discuss risks and benefits of screening, and provide screening services. However, Black men may encounter barriers to participation in these programs such as lack of health insurance, difficulty with travel to clinic, and challenges with navigating the medical system. To address these barriers, the Prostate Cancer Risk, Education and Assessment in the Community with Help (REACH) project was developed as a community-based extension of a comprehensive prostate cancer risk assessment program (PRAP) at Fox Chase Cancer Center (FCCC). This is a pilot project to evaluate the feasibility and acceptability of a community-based risk assessment program.

Methods: Developing the REACH project infrastructure included: 1) choosing a clinic site; 2) establishing patient access procedures; 3) establishing navigator services; 4) developing procedures for subsidy fund use; and 5) recruitment and promotion. Given the challenges of establishing a community site, we chose to utilize our mobile mammography van as the screening venue. Evaluation measures included recruitment and participation rates, utilization of patient navigation services, as well as patient satisfaction. A self-administered survey assessed the distance travelled to receive screening services, whether or not they utilized patient navigator services, the importance of having a community screening site in their decision to participate (5-point Likert scale), the importance of having a patient navigator to assist (5-point Likert scale), satisfaction with any patient navigation services provided (5-point Likert scale), and overall satisfaction with the program (5-point Likert scale).

Results: As of April 2011, 35 men have called regarding the program. Of these, 20 were eligible and 13 men have received prostate cancer risk assessment services through Prostate REACH. Twelve participants were screened on the van and one patient at the FCCC PRAP clinic. The majority of participants are Black men. The mean age at enrollment is 48.6 years (range 36–64 years). Approximately 69% of participants received patient navigation services. The patient navigator contacted each participant on average three times to address barriers. Insurance issues were the most common barrier (88%) addressed by the navigator. Support issues (emotional and caregiver) also were addressed. All participants completed the user survey following their screening. Nearly 70% of men travelled five miles or less to be screened, and 54% reported that they utilized patient navigation services (slightly under the 69% who actually did receive some navigation). The majority of participants thought having a community screening location and a patient navigator was important for participation. The majority of participants were quite a bit to extremely satisfied with the overall REACH program (Mean=4.85, SD=0.38). Conclusions: The REACH experience highlights specific implementation challenges faced in expanding access to prostate cancer risk assessment to underserved men. Patient navigation services may be essential to participation among underserved populations. Future research should explore various recruitment strategies to increase participation.

Citation Information: Cancer Epidemiol Biomarkers Prev 2011;20(10 Suppl):B13.

Abstract B5: Region Five GMaP/BMaP Network: Preliminary findings from the comprehensive needs assessment principal investigator survey

Background: The Region Five GMaP/BMaP Network is a regional partnership representing 18 NCI funded institutions charged with the development and implementation of a comprehensive needs assessment (CNAT). The goal of the principle investigator (PI) component of the CNAT was to capture in-depth PI opinion on necessary elements to successful health disparities research, barriers to success and required funding and infrastructure elements needed to alleviate those barriers. In addition, we hoped to obtain specific recommendations for our network's development to foster successful research collaborations amongst our many institutions and the diverse populations we serve.

Methods: The CNAT consisted of a mixed methods approach utilizing four instruments: A principal Investigator Survey and PI Interview and a Biospecimen Facility Survey and Interview. This presentation focuses on preliminary findings from the PI Survey. The surveys were conducted online by PI's during the months of March and April 2011. Qualitative interviews will be conducted between July and August 2011. The PI survey consisted of 48 distinct questions, with affiliated subset questions that covered seven core areas: cancer health disparities research/community, minority biospecimens collection, clinical trials recruitment and retention, bioinformatics/advanced & emerging technology, training, visioning the future; and network analysis.

Results: PI online survey was completed by 14 of 18 region five institutions, a 77.8% completion rate. Preliminary findings show our region's investigator expertise is in the areas of CBPR, working with community based organizations, and training CHD researchers, with 84% (11/13) reporting collaborations with institutions and community partners. Most of the populations focused on among the PI's mirrors the populations in institution service areas. Forty-six percent (6/13) of institutions reported having implemented outreach or education strategies in the community to promote biospecimens research, while 69.2% (9/13) reported projects with the aim to improve accrual of minority patients into clinical trials. Four PI's focus 50–100% of their GMaP effort on health disparities programs; while five PI's focus between 50–100% of their GMaP group effort on health disparities research. 84% of PI's collaborate with others to conduct CHD research and community outreach. The most popular areas of CHD research are barriers to cancer screening, health literacy, and cancer (breast, prostate, cervical, and lung).

Conclusions: Region Five has significant experience conducting community-based research and community education programs to increase minority/medically underserved population's participation in research. There are opportunities for collaboration among principal investigators and biospecimen facilities around minority biospecimen collection efforts. Region Five has established a formal network called the Cancer Disparities Research Network (CDRN) and is establishing a network website. A result of this preliminary network is the continuation of the collaboration and identification of potential health disparities projects. We anticipate implementing Cancer 102 education and training on research participation, biospecimen donation/biobanking and genetics across our institutions.

Citation Information: Cancer Epidemiol Biomarkers Prev 2011;20(10 Suppl):B5.

Validation of the group-based medical mistrust scale among urban black men

BACKGROUND

Socioculturally relevant measures of medical mistrust are needed to better address health disparities, especially among Black men, a group with lower life expectancy and higher death rates compared to other race/gender groups.

OBJECTIVES

The study aim was to investigate the psychometric properties of the Group-Based Medical Mistrust Scale (GBMMS) in a Black male sample.

DESIGN

Data were collected as part of a randomized controlled trial testing educational strategies to support Black men's decisions about prostate cancer screening.

PARTICIPANTS

Participants included 201 Black men ages 40-75 years recruited in New York City during 2006-2007.

MAIN MEASURES

The primary measures included: race-based medical mistrust, health care participation, avoidance of health care, perceived access to health care, health care satisfaction, racial identity, residential racial segregation, attitudes towards prostate cancer screening, and past prostate cancer screening behavior.

KEY RESULTS

An exploratory factor analysis suggested a three-factor structure. Confirmatory factor analysis supported the three-factor model. Internal consistency was high for the total GBMMS and the three sub-scales: Suspicion, Discrimination, and Lack of Support. Construct validity was supported by: significant positive correlations between GBMMS and avoidance of health care and racial identity as well as significant negative correlations with health care access, health care satisfaction, and attitudes about prostate cancer screening. ANOVA showed that the GBMMS was associated with greater residential racial segregation. Higher total GBMMS scores were associated with not visiting a physician in the last year and not having a regular physician.

CONCLUSIONS

The present findings provide strong additional evidence that the GBMMS is a valid and reliable measure that may be used among urban Black men.

Evidence for a vicious cycle of exercise and hypoglycemia in type 1 diabetes mellitus

Exercise is a cornerstone of diabetes management as it aids in glycemic control, weight management, reducing blood pressure, and improving the quality of life of patients. Unfortunately, owing to the complexity and difficulties of regulating exogenous insulin in a physiologic manner during exercise, physical activity often results in hypoglycemia in patients with type 1 diabetes mellitus (type 1 DM). When glucose levels fall below threshold glycemic levels, neuroendocrine, autonomic nervous system (ANS), and metabolic glucose counterregulatory mechanisms are activated. These hypoglycemic counterregulatory mechanisms in type 1 DM can be blunted irreversibly by disease duration or by acute episodes of prior stress. These reduced (or absent) counterregulatory responses result in a threefold increase in severe hypoglycemia when intensive glycemic control is implemented in type 1 DM. Much recent work has been focused on determining the in vivo mechanisms responsible for causing the increased incidence of severe hypoglycemia in type 1 DM. Studies from several laboratories have demonstrated the role played by episodes of antecedent hypoglycemia in producing blunted glucose counterregulatory responses during subsequent exposures of hypoglycemia. Until recently, the mechanisms responsible for exercise related hypoglycemia in type 1 DM have been attributed to relative or absolute increases of insulin levels or incomplete glycogen repletion after physical activity. Owing to the qualitative similarity of neuroendocrine, ANS, and metabolic responses to hypoglycemia and exercise, we have hypothesized that neuroendocrine and ANS counterregulatory dysfunction may also play an important role in the pathogenesis of exercise-related hypoglycemia in type 1 DM. Vicious cycles can be created in type 1 DM, where an episode of hypoglycemia or exercise can feed forward to downregulate neuroendocrine and ANS responses to a subsequent episode of either stress, thereby creating further hypoglycemia. This article will review the recent work that has studied the contribution of counterregulatory dysfunction to exercise-induced hypoglycemia in type 1 DM.

Acute fructose administration improves oral glucose tolerance in adults with type 2 diabetes

OBJECTIVE

In normal adults, a small (catalytic) dose of fructose administered with glucose decreases the glycemic response to a glucose load, especially in those with the poorest glucose tolerance. We hypothesized that an acute catalytic dose of fructose would also improve glucose tolerance in individuals with type 2 diabetes.

RESEARCH DESIGN AND METHODS

Five adults with type 2 diabetes underwent an oral glucose tolerance test (OGTT) on two separate occasions, at least 1 week apart. Each OGTT consisted of 75 g glucose with or without the addition of 7.5 g fructose (OGTT + F or OGTT - F), in random order. Arterialized blood samples were collected from a heated dorsal hand vein twice before ingestion of the carbohydrate and every 15 min for 3 h afterward.

RESULTS

The area under the curve (AUC) of the plasma glucose response was reduced by fructose administration in all subjects; the mean AUC during the OGTT + F was 14% less than that during the OGTT - F (P < 0.05). The insulin AUC was decreased 21% with fructose administration (P = 0.2). Plasma glucagon concentrations declined similarly during OGTT - F and OGTT + F. The incremental AUC of the blood lactate response during the OGTT - F was approximately 50% of that observed during the OGTT + F (P < 0.05). Neither nonesterified fatty acid nor triglyceride concentrations differed between the two OGTTs.

CONCLUSIONS

Low-dose fructose improves the glycemic response to an oral glucose load in adults with type 2 diabetes, and this effect is not a result of stimulation of insulin secretion.

The effects of HDV-insulin on carbohydrate metabolism in Type 1 diabetic patients

The aim of this study was to compare the metabolic effects of a single equimolar subcutaneous injection of hepatic directed vesicle-insulin (HDV-insulin) and regular insulin on glucose levels and intermediary metabolism during a 75-g oral glucose tolerance test (OGTT). Nine Type 1 diabetic patients underwent two experiments separated by 4 weeks. Each experimental protocol consisted of an identical evening meal followed by overnight euglycemic control achieved by a continuous low-dose insulin infusion. The next morning a subcutaneous injection (0.1 U/kg) of HDV-insulin or regular insulin was administered 30 min before a 75-g OGTT. The overnight basal insulin infusion was maintained unaltered throughout the 150-min OGTT. Plasma glucose, glucoregulatory hormones (insulin, glucagon, cortisol), and intermediary metabolites (lactate, alanine, glycerol, NEFA, beta-hydroxybutyrate) were measured to assess the metabolic effects of the two insulin preparations. Compared to regular insulin, an equivalent subcutaneous dose of HDV-insulin significantly lowered glucose levels during OGTT (mean reduction 2.2+/-0.4 mmol/l; P<.005). Plasma levels of insulin and glucagon were equivalent during both series of experiments. Blood lactate, glycerol and plasma NEFA levels were not different during OGTT indicating similar peripheral action of the insulins. beta-Hydroxybutyrate levels were significantly reduced (P<.05) following HDV-insulin supporting a preferential hepatic action of the preparation. We conclude that HDV-insulin can significantly lower plasma glucose excursions compared to an equivalent dose of regular insulin during an OGTT in Type 1 diabetic patients. The metabolic profile of equivalent peripheral insulin, glucagon and glycerol levels but reduced beta-hydroxybutyrate values support a hepatospecific effect of HDV-insulin.

Sexual dimorphism in counterregulatory responses to hypoglycemia after antecedent exercise

After antecedent hypoglycemia, counterregulatory responses to subsequent hypoglycemia exhibit greater blunting in men than in women. Because physical exercise and hypoglycemia share multiple counterregulatory mechanisms, we hypothesized that prior exercise may also result in gender-specific blunting of counterregulatory responses to subsequent hypoglycemia. Thirty healthy subjects (15 women and 15 men; age, 28 +/- 3 yr; body mass index, 23 +/- 1 kg/m2) were studied during 2-d experiments. Day 1 consisted of either identical 90-min morning and afternoon cycle exercise at 50% maximum oxygen expenditure or two 2-h episodes of hyperinsulinemic euglycemia. Day 2 consisted of a 2-h morning hyperinsulinemic-hypoglycemic clamp. Endogenous glucose production was measured using [3-(3)H]glucose. Muscle sympathetic nerve activity was measured using microneurography. Day 2 insulin (540 +/- 36 pmol/liter) and plasma glucose (2.9 +/- 0.06 pmol/liter) levels were similar in men and women during the last 30 min of hypoglycemia. Compared with antecedent euglycemia, d 1 exercise produced significant blunting of d 2 counterregulatory responses to hypoglycemia. Several key d 2 counterregulatory responses were blunted to a greater extent in men than in women: glucagon (men, -105 +/- 14; women, -25 +/- 7 ng/liter; P < 0.0001), epinephrine (men, -2625 +/- 257 pmol/liter; women, -212 +/- 573; P < 0.001), norepinephrine (men, -0.50 +/- 0.12 nmol/liter; women, -0 +/- 0.11; P < 0.001), and muscle sympathetic nerve activity (men, -13 +/- 4; women, -4 +/- 4 bursts/min; P < 0.01). Cardiovascular responses (heart rate and systolic and mean arterial blood pressures) were also more blunted by antecedent exercise in men than in women. After d 1 exercise, the amount of glucose infused during d 2 hypoglycemia in men was increased 6-fold compared with that after d 1 euglycemia. This amount was significantly increased (P < 0.01) compared with the 2-fold (P < 0.01) increment in glucose infusion that was required in women after d 1 exercise. Lipolysis was unaffected by d 1 exercise in women, but was significantly blunted during d 2 hypoglycemia in men. In summary, two bouts of prolonged, moderate exercise (90 min at 50% maximum oxygen expenditure) induced a marked sexual dimorphism in key neuroendocrine (glucagon, catecholamines, and muscle sympathetic nerve activity) and metabolic (glucose kinetic, lipolysis) responses to next day hypoglycemia.

Effect of morning exercise on counterregulatory responses to subsequent, afternoon exercise

The aim of this study was to determine whether a bout of morning exercise (EXE(1)) can alter neuroendocrine and metabolic responses to subsequent afternoon exercise (EXE(2)) and whether these changes follow a gender-specific pattern. Sixteen healthy volunteers (8 men and 8 women, age 27 +/- 1 yr, body mass index 23 +/- 1 kg/m(2), maximal O(2) uptake 31 +/- 2 ml x kg(-1) x min(-1)) were studied after an overnight fast. EXE(1) and EXE(2) each consisted of 90 min of cycling on a stationary bike at 48 +/- 2% of maximal O(2) uptake separated by 3 h. To avoid the confounding effects of hypoglycemia and glycogen depletion, carbohydrate (1.5 g/kg body wt po) was given after EXE(1), and plasma glucose was maintained at euglycemia during both episodes of exercise by a modification of the glucose-clamp technique. Basal insulin levels (7 +/- 1 microU/ml) and exercise-induced insulin decreases (-3 microU/ml) were similar during EXE(1) and EXE(2). Plasma glucose was 5.2 +/- 0.1 and 5.2 +/- 0.1 mmol/l during EXE(1) and EXE(2), respectively. The glucose infusion rate needed to maintain euglycemia during the last 30 min of exercise was increased during EXE(2) compared with EXE(1) (32 +/- 4 vs. 7 +/- 2 micromol x kg(-1) x min(-1)). Although this increased need for exogenous glucose was similar in men and women, gender differences in counterregulatory responses were significant. Compared with EXE(1), epinephrine, norepinephrine, growth hormone, pancreatic polypeptide, and cortisol responses were blunted during EXE(2) in men, but neuroendocrine responses were preserved or increased in women. In summary, morning exercise significantly impaired the body's ability to maintain euglycemia during later exercise of similar intensity and duration. We conclude that antecedent exercise can significantly modify, in a gender-specific fashion, metabolic and neuroendocrine responses to subsequent exercise.

Effects of antecedent prolonged exercise on subsequent counterregulatory responses to hypoglycemia

In the present study the hypothesis tested was that prior exercise may blunt counterregulatory responses to subsequent hypoglycemia. Healthy subjects [15 females (f)/15 males (m), age 27 +/- 1 yr, body mass index 22 +/- 1 kg/m(2), hemoglobin A(Ic) 5.6 +/- 0.5%] were studied during 2-day experiments. Day 1 involved either 90-min morning and afternoon cycle exercise at 50% maximal O2 uptake (VO2(max)) (priorEXE, n = 16, 8 m/8 f) or equivalent rest periods (priorREST, n = 14, 7 m/7 f). Day 2 consisted of a 2-h hypoglycemic clamp in all subjects. Endogenous glucose production (EGP) was measured using [3-3H]glucose. Muscle sympathetic nerve activity (MSNA) was measured using microneurography. Day 2 insulin (87 +/- 6 microU/ml) and plasma glucose levels (54 +/- 2 mg/dl) were equivalent after priorEXE and priorREST. Significant blunting (P < 0.01) of day 2 norepinephrine (-30 +/- 4%), epinephrine (-37 +/- 6%), glucagon (-60 +/- 4%), growth hormone (-61 +/- 5%), pancreatic polypeptide (-47 +/- 4%), and MSNA (-90 +/- 8%) responses to hypoglycemia occurred after priorEXE vs. priorREST. EGP during day 2 hypoglycemia was also suppressed significantly (P < 0.01) after priorEXE compared with priorREST. In summary, two bouts of exercise (90 min at 50% VO2(max)) significantly reduced glucagon, catecholamines, growth hormone, pancreatic polypeptide, and EGP responses to subsequent hypoglycemia. We conclude that, in normal humans, antecedent prolonged moderate exercise blunts neuroendocrine and metabolic counterregulatory responses to subsequent hypoglycemia.

Effects of morning hypoglycemia on neuroendocrine and metabolic responses to subsequent afternoon hypoglycemia in normal man

There is general agreement that prior hypoglycemia blunts subsequent hypoglycemic counterregulatory responses. However, there is considerable debate concerning the timing and number of prior hypoglycemic episodes required to cause this blunting effect. The aim of this study was to determine whether one episode of hypoglycemia could modify neuroendocrine, metabolic, and symptom responses to hypoglycemia induced 2 h later. A total of 24 (12 male and 12 female) young, healthy, overnight-fasted subjects participated in a series of glucose clamp studies. A total of 16 individuals underwent 2 randomized studies of either identical 2-h morning and afternoon hyperinsulinemic (490 +/- 60 pmol/L) hypoglycemia (2.9 +/- 0.1 mmol/L) separated by 2 h or, at least 2 months later, 2-h morning and afternoon hyperinsulinemic (492 +/- 45 pmol/L) euglycemia (5.1 +/- 0.1 mmol/L). A total of 8 other subjects participated in a single experiment that consisted of 2-h morning hyperinsulinemic (516 +/- 60 pmol/L) euglycemia (5.1 +/- 0.1 mmol/L) and 2-h afternoon hyperinsulinemic (528 +/- 66 pmol/L) hypoglycemia (2.9 +/- 0.1 mmol/L) also separated by 2 h. Morning hypoglycemia significantly (P < 0.01) reduced (33-55%) the responses of epinephrine, norepinephrine, glucagon, GH, cortisol, and pancreatic polypeptide during afternoon hypoglycemia. Hypoglycemic symptoms (primarily neuroglycopenic) were also significantly (P < 0.01) reduced during afternoon hypoglycemia. Plasma glucose, insulin, nonesterified fatty acids, glycerol, lactate, beta-hydroxybutyrate (P < 0.01), GH, and cortisol (P < 0.05) levels were significantly increased at the start of afternoon hypoglycemia following morning hypoglycemia. Morning hypoglycemia created an insulin-resistant state during afternoon hypoglycemia. Despite blunted neuroendocrine responses, glucose infusion rates required to maintain hypoglycemia and increases in glucose oxidation were significantly attenuated during afternoon compared with morning hypoglycemia. This was in marked contrast to euglycemic control experiments where glucose infusion rates and nonoxidative glucose disposal were significantly increased during afternoon relative to morning studies. We conclude that in normal man one episode of prolonged, moderate, morning hypoglycemia can produce substantial blunting of neuroendocrine and symptomatic responses to subsequent near-term hypoglycemia, and the induction of posthypoglycemic insulin resistance can compensate for blunted neuroendocrine responses by limiting glucose flux and specifically glucose oxidation during subsequent near-term hypoglycemia.

Acute fructose administration decreases the glycemic response to an oral glucose tolerance test in normal adults

In animal models, a small (catalytic) dose of fructose administered with glucose decreases the glycemic response to the glucose load. Therefore, we examined the effect of fructose on glucose tolerance in 11 healthy human volunteers (5 men and 6 women). Each subject underwent an oral glucose tolerance test (OGTT) on 2 separate occasions, at least 1 week apart. Each OGTT consisted of 75 g glucose with or without 7.5 g fructose (OGTT+F or OGTT-F), in random order. Arterialized blood samples were obtained from a heated dorsal hand vein twice before ingestion of the carbohydrate and every 15 min for 2 h afterward. The area under the curve (AUC) of the change in plasma glucose was 19% less in OGTT+F vs. OGTT-F (P: < 0.05). Glucose tolerance was improved by fructose in 9 subjects and worsened in 2. All 6 subjects with the largest glucose AUC during OGTT-F had a decreased response during OGTT+F (31 +/- 5% decrease). The insulin AUC did not differ between the 2 studies. Of the 9 subjects with improved glucose tolerance during the OGTT+F, 5 had smaller insulin AUC during the OGTT+F than the OGTT-F. Plasma glucagon concentrations declined similarly during OGTT-F and OGTT+F. The blood lactate response was about 50% greater during the OGTT+F (P: < 0.05). Neither nonesterified fatty acid nor triglyceride concentrations differed between the two OGTT. In conclusion, low dose fructose improves the glycemic response to an oral glucose load in normal adults without significantly enhancing the insulin or triglyceride response. Fructose appears most effective in those normal individuals who have the poorest glucose tolerance.

Differential gender responses to hypoglycemia are due to alterations in CNS drive and not glycemic thresholds

The aims of this study were 1) to determine whether differential glycemic thresholds are the mechanism responsible for the sexual dimorphism present in neuroendocrine responses during hypoglycemia and 2) to define the differences in counterregulatory physiological responses that occur over a range of mild to moderate hypoglycemia in healthy men and women. Fifteen (8 male, 7 female) lean healthy adults underwent four separate randomized 2-h hyperinsulinemic (1.5 mU. kg(-1).min(-1)) glucose clamp studies at euglycemia (90 mg/dl) or hypoglycemia of 70, 60, or 50 mg/dl. Plasma insulin levels were similar during euglycemic and hypoglycemic studies (91-96 +/- 8 microU/ml) in men and women. Hypoglycemia of 70, 60, and 50 mg/dl all resulted in significant increases (P < 0.05, P < 0.01) in epinephrine, glucagon, growth hormone, cortisol, and pancreatic polypeptide levels compared with euglycemic studies in men and women. Plasma norepinephrine levels were increased (P < 0.05) only relative to euglycemic studies at a hypoglycemia of 50 mg/dl. Muscle sympathetic nerve activity (MSNA) increased significantly during hyperinsulinemic-euglycemic control studies. Further elevations of MSNA did not occur until hypoglycemia of 60 mg/dl in both men and women. Plasma epinephrine, glucagon, growth hormone, and pancreatic polypeptide were significantly increased in men compared with women during hypoglycemia of 70, 60, and 50 mg/dl. MSNA, heart rate, and systolic blood pressure responses were also significantly increased in men at hypoglycemia of 60 and 50 mg/dl. In summary, these studies have demonstrated that, in healthy men and women, the glycemic thresholds for activation of epinephrine, glucagon, growth hormone, cortisol, and pancreatic polypeptide occur between 70 and 79 mg/dl. Thresholds for activation of MSNA occur between 60 and 69 mg/dl, whereas norepinephrine is not activated until glycemia is between 50 and 59 mg/dl. We conclude that 1) differential glycemic thresholds are not the cause of the sexual dimorphism present in counterregulatory responses to hypoglycemia; 2) reduced central nervous system efferent input appears to be the mechanism responsible for lowered neuroendocrine responses to hypoglycemia in women; and 3) physiological counterregulatory responses (neuroendocrine, cardiovascular, and autonomic nervous system) are reduced across a broad range of hypoglycemia in healthy women compared with healthy men.

Effects of differing durations of antecedent hypoglycemia on counterregulatory responses to subsequent hypoglycemia in normal humans

The aim of this study was to determine whether the duration of antecedent hypoglycemia regulates the magnitude of subsequent counterregulatory failure. A total of 31 lean healthy overnight-fasted individuals (16 men/15 women) were studied. There were 15 subjects (8 men/7 women) who underwent two separate 2-day randomized experiments separated by at least 2 months. On day 1, 2-h hyperinsulinemic (9 pmol x kg(-1) x min(-1)) euglycemic (5.2 +/- 0.1 mmol/l) or hypoglycemic (2.9 +/- 0.1 mmol/l) glucose clamps (prolonged hypoglycemia) were carried out in the morning and afternoon. Of the other subjects, 16 participated in a 2-day study in which day 1 consisted of morning and afternoon short-duration hypoglycemia experiments (hypoglycemic nadir of 2.9 +/- 0.1 mmol for 5 min), and 10 of these individuals underwent an additional 2-day study in which day 1 consisted of morning and afternoon intermediate-duration hypoglycemia (hypoglycemic nadir of 2.9 +/- 0.1 mmol for 30 min). The next morning (day 2) all subjects underwent an additional 2-h hyperinsulinemic-hypoglycemic clamp (2.9 +/- 0.1 mmol/l). The rate of fall of glucose (0.07 mmol/min) was carefully controlled during all hypoglycemic studies so that the glucose nadir was reached at 30 min. Despite equivalent day 2 plasma glucose and insulin levels, there were significant differences in counterregulatory physiological responses. Steady-state epinephrine, glucagon, growth hormone, cortisol, and pancreatic polypeptide levels were similarly significantly blunted (P < 0.01) by the differing duration day 1 hypoglycemia compared with day 1 euglycemia. Muscle sympathetic nerve activity and endogenous glucose production were also similarly blunted (P < 0.01) by day 1 hypoglycemia (relative to day 1 euglycemia). Day 2 hypoglycemic symptoms were significantly reduced (P < 0.01) after day 1 prolonged intermediate- but not short-duration hypoglycemia. In summary, two episodes of short-duration moderate hypoglycemia can produce significant blunting of key neuroendocrine and metabolic counterregulatory responses. Hypoglycemic symptom scores are reduced by prolonged but not short-duration prior hypoglycemia. We conclude that in healthy overnight fasted humans, 1) neuroendocrine, autonomic nervous system, and metabolic counterregulatory responses are sensitive to the blunting effects of even short-duration prior hypoglycemia, and 2) the duration of antecedent hypoglycemia results in a hierarchy of blunted physiological responses with hypoglycemic symptom awareness less vulnerable than neuroendocrine responses.

Effects of insulin per se on neuroendocrine and metabolic counter-regulatory responses to hypoglycaemia

We examined and compared findings from studies aimed at detecting and quantifying an effect of insulin per se on counter-regulatory responses to hypoglycaemia. The experimental protocols used in many of these studies were very different with regard to study design and patient population, resulting at times in inconsistencies and discrepancies. Taken together, the results from this extensive body of work clearly indicate that, at similar levels of hypoglycaemia, greater hyperinsulinaemia results in enhanced counter-regulatory responses. This enhancement includes higher circulating levels of counter-regulatory hormones (adrenaline, noradrenaline, cortisol and growth hormone, but not glucagon), more intense activation of hypoglycaemic symptoms (both neural-sympathetic and adrenal-sympathetic), and greater deterioration of neuropsychological skills. The insulin-induced enhancement of counter-regulatory responses is not influenced by gender, is present in several animal species, and applies to healthy subjects as well as to patients with Type I diabetes. The underlying mechanisms remain speculative, and possibly include a direct neuromodulatory effect and/or suppression of glucose utilization in various areas of the brain, which either independently or in a hierarchical fashion trigger the sequence of downstream counter-regulatory events.

Activity and dosage of alteplase dilution for clearing occlusions of venous-access devices

The activity and sterility of reconstituted alteplase solution and the effectiveness of an alteplase dose-escalation protocol for the clearance of midline-catheter and central-venous-access device occlusions were studied. Reconstituted alteplase solution was stored at -70, -25, or 2 degrees C at concentrations of 0.5, 1, or 2 mg/mL. Durations of storage in the freezer were 0, 7, and 14 days, and durations of storage in the refrigerator were 0, 48, and 72 hours and 7 and 14 days. Samples were also assayed and cultured without prior freezing after refrigeration at 2 degrees C for 0, 48, and 72 hours and 7, 14, and 28 days. Fifty-eight pediatric and adult patients were enrolled in a separate study in which catheter clearance was initiated with alteplase 0.5 mg, and the dose was escalated to 1 and 2 mg sequentially until the catheter was cleared. The primary endpoint was restoration of catheter patency, and the secondary endpoint was the occurrence of bleeding episodes within 24 hours of alteplase administration. Catheter removal due to failure to restore patency was also documented. The activity and sterility of alteplase were maintained under all conditions studied. Fifty catheters (86.2%) were cleared with alteplase 0.5 mg, 5 (8.6%) after dose escalation to 1 mg, and 1 (1.7%) after escalation to 2 mg. The alteplase solution did not clear the occlusion in 2 catheters (3.4%): 1 had a mechanical obstruction and 1 cleared two hours after the 1-mg dose was deemed a failure. None of the six catheter removals was due to recalcitrant clots. Bleeding observed was not considered to be the result of alteplase administration. For use in clearing occlusions of venous-access devices, alteplase 0.5, 1, and 2 mg/mL retained sufficient fibrinolytic activity when stored for up to 14 days at 2 degrees C (28 days for the 0.5-mg/mL dilution) and when stored for 14 days at -70 or -25 degrees C followed by up to 14 days at 2 degrees C. The dose-escalation protocol was effective.

Gender-related differences in counterregulatory responses to antecedent hypoglycemia in normal humans

Compared to men, inherent counterregulatory responses are reduced in healthy and type 1 diabetic women. Despite this, the prevalence of hypoglycemia in patients with type 1 diabetes (type 1 DM) is gender neutral. The aim of this study was to determine the in vivo mechanism(s) responsible for this apparent clinical paradox. The central importance of antecedent hypoglycemia in causing subsequent counterregulatory failure is now established. We, therefore, hypothesized that a gender-related difference to the blunting effects of prior hypoglycemia may exist, and this could explain why type 1 DM women do not have an increased prevalence of hypoglycemia despite reduced counterregulatory responses. Fifteen healthy male and female individuals (eight men and seven women) underwent four separate 2-day experimental protocols in a randomized fashion. Day 1 involved identical morning and afternoon 2-h hyperinsulinemic (9 pmol/kg x min) glucose clamp studies with 5.1 +/- 0.1, 3.9 +/- 0.1, 3.3 +/- 0.1, or 2.9 +/- 0.1 mmol/L. Day 2 consisted of a single 2-h hypoglycemic clamp of 2.9 +/- 0.1 mmol/L. Insulin levels were similar on both days of each protocol in men and women. After day 1 euglycemia (5.1 +/- 0.1 mmol/L), day 2 counterregulatory responses were significantly increased (P < 0.01) in men relative to women. In women, counterregulatory responses were resistant to the effects of day 1 hypoglycemia. Antecedent hypoglycemia of 3.9, 3.3, and 2.9 +/- 0.1 mmol/L produced 3 +/- 2%, 5 +/- 2%, and 25 +/- 4% aggregate reductions in day 2 neuroendocrine, muscle sympathetic nerve activity, and metabolic counterregulatory responses. In marked contrast, identical day 1 hypoglycemia of 3.9, 3.3, and 2.9 +/- 0.1 mmol/L in men produced significantly greater reductions in day 2 counterregulatory responses of 30 +/- 6%, 39 +/- 6%, and 52 +/- 6%, respectively. The net effect of the differential gender effects of antecedent hypoglycemia was to overcome the usually increased (50%) sympathetic nervous system (SNS) counterregulatory responses to hypoglycemia found in men. We conclude that 1) antecedent hypoglycemia produces less blunting of counterregulatory responses to subsequent hypoglycemia in women relative to men; 2) two episodes of antecedent hypoglycemia can overcome the greater SNS response to hypoglycemia usually found in men; and 3) the reduced susceptibility of women to the blunting effects of antecedent hypoglycemia may be the mechanism explaining why, despite inherently reduced SNS counterregulatory responses, female type 1 DM patients have a similar prevalence of hypoglycemia compared to men.

Advances in oral therapy for type 2 diabetes

The complications of diabetes mellitus, arising from inadequate glycemic control, have serious consequences for society as well as individuals. It is now urged that tight glycemic control be the goal for all patients, regardless of type of diabetes. Unfortunately, hypoglycemia can be a consequence of this aggressive approach. Treatment with a combination of agents and improved therapies are needed to maintain glycemic balance in patients. A better understanding of the pathophysiology of diabetes has yielded many treatment options based on various mechanisms of action. The sulfonyluereas, repaglinide, metformin, acarbose and the thiazolidinediones are effective in decreasing fasting plasma glucose levels, but their limitations may include adverse effects, such as weight gain and hypoglycemia, and an inability to modify some of the important comorbidities of diabetes. Therapies aimed at treating mealtime hyperglycemia are gaining attention. One promising investigational agent in this category is nateglinide. Early data suggest that its rapid onset and short duration of action result in increased early mealtime insulin release, reduced mealtime glucose excursions, and improved glycemic control.

Comparative effectiveness of low-molecular-weight heparins after therapeutic interchange

Management Case Studies describe approaches to real-life management problems in health systems. Each installment is a brief description of a problem and how it was dealt with. The cases are intended to help readers deal with similar experiences in their own work sites. Problem solving, not hypothesis testing, is emphasized. Successful resolution of the management issue is not a criterion for publication-important lessons can be learned from failures, too.

Hypoglycemic counterregulatory responses differ between men and women with type 1 diabetes

The aim of this study was to determine whether sex-related differences occur in counterregulatory responses to hypoglycemia in adult type 1 diabetic patients. Experiments were carried out on 16 (8 men/8 women) type 1 diabetic patients and compared with 16 (8 men/8 women) age- and weight-matched normal individuals. Men and women with type 1 diabetes were matched for age (26+/-2 vs. 25+/-1 years), duration of diabetes (9+/-1 vs. 8+/-1 years), glycemic control (HbA1c 7.7+/-0.3 vs. 7.8+/-0.2%), and weight (BMI 22.8+/-1 vs. 22.1+/-1 kg/m2), respectively. After normalizing plasma glucose overnight, patients underwent a 2-h hyperinsulinemic-hypoglycemic clamp study. Plasma glucose (3.0+/-0.1 mmol/l) and insulin (510+/-48 pmol/l) levels were equated in all groups. Plasma epinephrine, norepinephrine, growth hormone (GH), muscle sympathetic nerve activity (MSNA), and endogenous glucose production (EGP) responses were significantly lower (P<0.01) in type 1 diabetic women compared with men. Autonomic symptom scores, lipid oxidation, nonesterified fatty acids (NEFAs), and glycerol responses were equivalent between men and women with type 1 diabetes despite significantly reduced sympathoadrenal and MSNA responses in women. Autonomic nervous system (ANS) and EGP responses were equivalent in type 1 diabetic and normal individuals. However, lipid oxidation (assessed by indirect calorimetry), glycerol, and NEFA responses were increased (P<0.01) in type 1 diabetic patients compared with normal control subjects. We conclude that counterregulatory responses to fixed hypoglycemia differ markedly in men and women with type 1 diabetes: 1) sympathetic nervous system, GH, and EGP responses are significantly reduced in type 1 diabetic women, 2) autonomic symptom awareness and lipolytic responses appear to be relatively increased in type 1 diabetic women compared with men, and 3) during conditions of similar hyperinsulinemic hypoglycemia and ANS drive, lipid oxidation and lipolytic responses can be increased in type 1 diabetic patients compared with normal individuals.

Effects of gender on neuroendocrine and metabolic counterregulatory responses to exercise in normal man

Significant, sexual dimorphisms exist in counterregulatory responses to commonly occurring stresses, such as hypoglycemia, fasting, and cognitive testing. The question of whether counterregulatory responses differ during exercise in healthy men and women remains controversial. The aim of this study was to determine whether a sexual dimorphism exists in neuroendocrine, metabolic, or cardiovascular responses to prolonged moderate exercise. Sixteen healthy (eight men and eight women) subjects matched for age (28+/-2 yr), body mass index (22+/-1 kg/m2), nutrient intake, and spectrum of physical fitness were studied in a randomized fashion during 90 min of exercise on a cycle ergometer at 80% of their anaerobic threshold (approximately 50% VO2 max). Respiratory quotient and oxygen consumption relative to body weight were identical in men and women. Glycemia was equated (5.3+/-0.2 mmol/L) during exercise via an exogenous glucose infusion. Gender had significant effects on counterregulatory responses during exercise. Arterialized epinephrine (1.05+/-0.2 vs. 0.45+/-0.04 nmol/L), norepinephrine (9.2+/-1.1 vs. 5.8+/-1.1 nmol/L), and pancreatic polypeptide (52+/-6 vs. 37+/-6 pmol/L) were significantly (P<0.01) increased in men compared to women, respectively. Plasma glucagon, cortisol, and GH levels responded similarly in men and women. Insulin values were higher at baseline in men and fell by a greater amount to reach similar levels during exercise compared to those in women. Endogenous glucose production, measured with [3-3H]glucose was similar in men and women. Carbohydrate oxidation was significantly increased in men relative to women (21.2+/-2 vs. 15.6+/-2 mg/kg fat free mass x min; P<0.05). Despite reduced sympathetic nervous system (SNS) drive, lipolytic responses were increased in women. Arterialized blood glycerol (215+/-30 vs. 140+/-20 micromol/L), beta-hydroxybutyrate (54+/-9 vs. 25+/-10 micromol/L), and plasma nonesterified fatty acids (720+/-56 vs. 469+/-103 micromol/L) were significantly (P<0.01) increased in women. In keeping with increased SNS activity, systolic blood pressure and mean arterial pressure were significantly increased (P<0.01) in men. In summary, this study demonstrates that a significant sexual dimorphism exists in neuroendocrine, metabolic, and cardiovascular counterregulatory responses to prolonged moderate exercise in man. We conclude that during exercise, men have increased autonomic nervous system (epinephrine, norepinephrine, pancreatic polypeptide), cardiovascular (systolic, mean arterial pressure) and certain metabolic (carbohydrate oxidation) counterregulatory responses, but that women have increased lipolytic (glycerol, nonesterified fatty acids) and ketogenic (beta-hydroxybutyrate) responses. Women may compensate for diminished SNS activity during exercise by increased lipolytic responses.

Effects of antecedent hypoglycemia on subsequent counterregulatory responses to exercise

Antecedent hypoglycemia can blunt counterregulatory responses to subsequent hypoglycemia. It is uncertain, however, if prior hypoglycemia can blunt counterregulatory responses to other physiologic stresses. The aim of this study, therefore, was to determine whether antecedent hypoglycemia attenuates subsequent neuroendocrine and metabolic responses to exercise. Sixteen lean, healthy adults (eight men and eight women, ages 28+/-2 years, BMI 22+/-1 kg/m2, VO2max 43+/-3 ml x kg(-1) x min(-1)) were studied during 2-day protocols on two randomized occasions separated by 2 months. On day 1, subjects underwent morning and afternoon 2-h hyperinsulinemic (528+/-30 pmol/l) glucose clamp studies of 5.3+/-0.1 mmol/l (euglycemic control) or 2.9+/-0.1 mmol/l (hypoglycemic study). On day 2, subjects underwent 90 min of exercise on a static cycle ergometer at 80% of their anaerobic threshold (approximately 50% VO2max). Glycemia was equated during day 2 exercise studies via an exogenous glucose infusion. Day 1 hypoglycemia had significant effects on neuroendocrine and metabolic responses during day 2 exercise. The usual exercise-induced reduction in insulin, together with elevations of plasma epinephrine, norepinephrine, glucagon, growth hormone, pancreatic polypeptide, and cortisol levels, was significantly blunted after day 1 hypoglycemia (P<0.01). Commensurate with reduced neuroendocrine responses, key metabolic counterregulatory mechanisms of endogenous glucose production (EGP), lipolytic responses, and ketogenesis were also significantly attenuated (P<0.01) after day 1 hypoglycemia. Significantly greater rates of glucose infusion were required to maintain euglycemia during exercise after day 1 hypoglycemia compared with day 1 euglycemia (8.8+/-2.2 vs. 0.6+/-0.6 micromol x kg(-1) x min(-1); P<0.01). During the first 30 min of exercise, day 1 hypoglycemia had little effect on EGP, but during the latter 60 min of exercise, day 1 hypoglycemia was associated with a progressively smaller increase in EGP compared with day 1 euglycemia. Thus, by 90 min, the entire exercise-induced increment in EGP (8.8+/-1.1 micromol x kg(-1) x min(-1)) was abolished by day 1 hypoglycemia. We conclude that 1) antecedent hypoglycemia results in significant blunting of essential neuroendocrine (glucagon, insulin, catecholamines) and metabolic (endogenous glucose production, lipolysis, ketogenesis) responses to exercise; 2) antecedent hypoglycemia may play a role in the pathogenesis of exercise-related hypoglycemia in type 1 diabetic patients; and 3) antecedent hypoglycemia can blunt counterregulatory responses to other physiologic stresses in addition to hypoglycemia.

Guidelines for nonemergency use of parenteral phenytoin products: proceedings of an expert panel consensus process. Panel on Nonemergency Use of Parenteral Phenytoin Products

This document summarizes the proceedings of an expert panel consensus process addressing the nonemergency use of parenteral phenytoin products for management of seizures in pediatric and adult patients. The algorithm and consensus statements developed by the expert panel emphasize strategies for lowering the probability of adverse events associated with the use of parenteral phenytoin products. Specific patient characteristics are defined to guide administration and monitoring of parenteral phenytoin therapy. The algorithm provides a decision pathway for the selection of the product and the route of administration of phenytoin sodium or fosphenytoin sodium after it has been determined that a parenteral phenytoin product is appropriate. Key factors covered in the algorithm include a list of patient characteristics and considerations necessary to prevent parenteral phenytoin adverse effects during selection of administration route and recommendations for monitoring of parenteral phenytoin therapy once it has been initiated. Situations requiring rapid attainment of high phenytoin concentrations, such as in the management of acute seizures, are not addressed in these guidelines.

Rates of glucagon activation and deactivation of hepatic glucose production in conscious dogs

To determine the time course of glucagon activation and deactivation of hepatic glucose production (HGP), studies were conducted in 18-hour fasted, conscious dogs. Somatostatin was infused with insulin replaced intraportally at 1.8 pmol x kg(-1) x min(-1) and glucagon replaced peripherally at 1.0 ng x kg(-1) x min(-1). After a 2-hour control period, glucagon infusion was either (1) increased fourfold for 4 hours (GGN 4X), (2) increased fourfold for 30 minutes and returned to a basal rate for 3.5 hours (GGN 4X/1X), or (3) fixed at the basal rate for 4 hours (GGN 1X). In the latter two protocols, glucose was infused peripherally to match glucose concentrations observed during GGN 4X. Glucose turnover was determined by deconvolution with the impulse response of the glucose system described by a two-compartment, time-varying model identified from high-performance liquid chromatography (HPLC)-purified [3-3H]glucose tracer data. In GGN 4X, HGP was stimulated from 15.2 +/- 0.9 micromol x kg(-1) x min(-1) to 52.7 +/- 6.5 micromol x kg(-1) x min(-1) after just 15 minutes, but it decreased over the subsequent 3 hours to a rate 25% above basal. In GGN 4X/1X, the increase in HGP during the first 30 minutes equaled that observed in GGN 4X, but when glucagon infusion was returned to basal, HGP decreased in 15 minutes to rates equal to those observed in GGN 1X. The times for half-maximal activation and deactivation of glucagon action were equal (4.5 +/- 1.0 and 4.0 +/- 1.1 minutes, respectively). The very rapid and sensitive hepatic response to glucagon makes pancreatic glucagon release a key component of minute-to-minute glucose homeostasis.

Effects of differing antecedent hypoglycemia on subsequent counterregulation in normal humans

The aim of the study was to determine the effects of specific levels of antecedent hypoglycemia on subsequent autonomic, neuroendocrine, and metabolic counterregulatory responses. Eight healthy, overnight-fasted male subjects were studied during 2-day protocols on four separate randomized occasions separated by at least 2 months. On day 1, insulin was infused at a rate of 9 pmol x kg(-1) x min(-1) and 2-h clamped euglycemia (plasma glucose 5.2 +/- 0.2 mmol/l) or differing hypoglycemia (plasma glucose 3.9 +/- 0.1, 3.3 +/- 0.1, or 2.9 +/- 0.1 mmol/l) was obtained during morning and afternoon. The next morning after an evening meal and 10-h overnight fast, each subject underwent a 2-h hyperinsulinemic (9 pmol x kg(-1) x min[-1]) hypoglycemic (2.9 +/- 0.1 mmol/l) clamp study. Despite equivalent day 2 plasma glucose and insulin levels, differing levels of antecedent hypoglycemia produced specific blunting of subsequent counterregulatory responses. Day 1 hypoglycemia of 3.9 mmol/l resulted in significantly (P < 0.01) blunted epinephrine, muscle sympathetic nerve activity, and glucagon responses. Day 1 hypoglycemia of 3.3 mmol/l resulted in additional significant blunting (P < 0.01) of pancreatic polypeptide, norepinephrine, growth hormone, endogenous glucose production, and lipolytic responses. Deeper day 1 hypoglycemia of 2.9 mmol/l produced similar day 2 counterregulatory failure as day 1 hypoglycemia of 3.3 mmol/l. In summary, in healthy overnight-fasted men, mild antecedent hypoglycemia of 3.9 mmol/l significantly blunts sympathoadrenal and glucagon, but not other forms of neuroendocrine counterregulatory responses, to subsequent hypoglycemia. Antecedent hypoglycemia of 3.3 mmol/l resulted in additional significant blunting of all major neuroendocrine and metabolic responses to subsequent hypoglycemia. We conclude that in normal humans, there is a hierarchy of blunted counterregulatory responses that are determined by the depth of antecedent hypoglycemia.

Prevention of an increase in plasma cortisol during hypoglycemia preserves subsequent counterregulatory responses

The aim of this study was to determine whether preventing increases in plasma cortisol during antecedent hypoglycemia preserves autonomic nervous system counterregulatory responses during subsequent hypoglycemia. Experiments were carried out on 15 (8 male/7 female) healthy, overnight-fasted subjects and 8 (4 male/4 female) age- and weight-matched patients with primary adrenocortical failure. 5 d before a study, patients had their usual glucocorticoid therapy replaced with a continuous subcutaneous infusion of cortisol programmed to produce normal daily circadian levels. Both groups underwent identical 2-d experiments. On day 1, insulin was infused at a rate of 1.5 mU/kg per min, and 2-h clamped hypoglycemia (53+/-2 mg/dl) was obtained during the morning and afternoon. The next morning, subjects underwent an additional 2-h hypoglycemic (53+/-2 mg/ dl) hyperinsulinemic clamp. In controls, day 2 steady state epinephrine, norepinephrine, pancreatic polypeptide, glucagon, growth hormone, and muscle sympathetic nerve activity were significantly blunted (P < 0.01) compared with day 1 hypoglycemia. In marked contrast, when increases of plasma cortisol were prevented in the patient group, day 2 neuroendocrine, muscle sympathetic nerve activity, hypoglycemic symptoms, and metabolic counterregulatory responses were equivalent with day 1 results. We conclude that (a) prevention of increases of cortisol during antecedent hypoglycemia preserves many critical autonomic nervous system counterregulatory responses to subsequent hypoglycemia; (b) hypoglycemia-induced increases in plasma cortisol levels are a major mechanism responsible for causing subsequent hypoglycemic counterregulatory failure; and (c) our results suggest that other mechanisms, apart from cortisol, do not play a major role in causing hypoglycemia-associated autonomic failure.

Brain of the conscious dog is sensitive to physiological changes in circulating insulin

The aim of this study was to determine whether a selective, physiologically relevant increase in blood-borne insulin perfusing the brain has an impact on the counterregulatory response to hypoglycemia. Experiments were carried out on 12 conscious 18-h-fasted dogs. Insulin was infused (1 mU x kg(-1) x min(-1)) in separate, randomized studies into a peripheral vein (n = 6) or both carotid and vertebral arteries (n = 6). This resulted in equivalent systemic insulinemia (38 +/- 2 vs. 35 +/- 5 microU/ml) but differing head insulin levels (38 +/- 2 microU/ml during peripheral infusion and an estimated 90 microU/ml during head insulin infusion). Glucose was infused during peripheral insulin infusion to equate the level of hypoglycemia (58 +/- 2 mg/dl) to that obtained during head insulin infusion (57 +/- 2 mg/dl). Despite equivalent peripheral insulin levels and hypoglycemia, incremental area under the curve responses for epinephrine, glucagon and cortisol were increased during head insulin infusion (P < 0.05). Net hepatic glucose output, gluconeogenesis, and lipolysis were increased 50-100% (P < 0.05) during head compared with peripheral insulin infusion. We conclude that during hypoglycemia in the conscious dog 1) physiologically relevant increases of blood-borne insulin to the head can amplify neuroendocrine and metabolic counterregulatory responses and 2) glucagon secretion can be regulated, in part, by neural efferent activity.

Role of cortisol in the pathogenesis of deficient counterregulation after antecedent hypoglycemia in normal humans

The aim of this study was to determine the role of increased plasma cortisol levels in the pathogenesis of hypoglycemia-associated autonomic failure. Experiments were carried out on 16 lean, healthy, overnight fasted male subjects. One group (n = 8) underwent two separate, 2-d randomized experiments separated by at least 2 mo. On day 1 insulin was infused at a rate of 1.5 mU/kg per min and 2 h clamped hypoglycemia (53 +/- 2 mg/dl) or euglycemia (93 +/- 3 mg/dl) was obtained during morning and afternoon. The next morning subjects underwent a 2-h hyperinsulinemic (1.5 mU/kg per min) hypoglycemic (53 +/- 2 mg/dl) clamp study. In the other group (n = 8), day 1 consisted of morning and afternoon 2-h clamped hyperinsulinemic euglycemia with cortisol infused to stimulate levels of plasma cortisol occurring during clamped hypoglycemia (53 mg/dl). The next morning (day 2) subjects underwent a 2-h hyperinsulinemic hypoglycemic clamp identical to the first group. Despite equivalent day 2 plasma glucose and insulin levels, steady state epinephrine, norepinephrine, pancreatic polypeptide, glucagon, ACTH and muscle sympathetic nerve activity (MSNA) values were significantly (R < 0.01) blunted after day 1 cortisol infusion compared to antecedent euglycemia. Compared to day 1 cortisol, antecedent hypoglycemia produced similar blunted day 2 responses of epinephrine, norepinephrine, pancreatic polypeptide and MSNA compared to day 1 cortisol. Antecedent hypoglycemia, however, produced a more pronounced blunting of plasma glucagon, ACTH, and hepatic glucose production compared to day 1 cortisol. We conclude that in healthy overnight fasted men (a) antecedent physiologic increases of plasma cortisol can significantly blunt epinephrine, norepinephrine, glucagon, and MSNA responses to subsequent hypoglycemia and (b) these data suggest that increased plasma cortisol is the mechanism responsible for antecedent hypoglycemia causing hypoglycemia associated autonomic failure.

Effects of an acute decrease in non-esterified fatty acid levels on muscle glucose utilization and forearm indirect calorimetry in lean NIDDM patients

The aim of the study was to evaluate an acute decrease in NEFA levels during an oral glucose tolerance test and its effects on glucose tolerance, muscle glucose uptake and muscle indirect calorimetry in ten lean non-insulin-dependent diabetic subjects. Two 75-g oral glucose tolerance tests were performed in random order. Placebo or 250 mg acipimox (to inhibit lipolysis) were administered orally 2 h before the start of the oral glucose tolerance test. Two hours after acipimox administration (time 0), non-esterified fatty acid, glycerol and 3-hydroxybutyrate levels decreased by 84, 68 and 77% respectively, compared to basal levels. Concomitantly, muscle lipid oxidation and non-oxidative glycolysis also decreased significantly. After placebo administration, non-esterified fatty acids, glycerol and 3-hydroxybutyrate and lipid oxidation increased by 29, 28, 106 and 33%, respectively (NS vs basal levels; p < 0.001 vs acipimox). There was a negative rate of net glucose storage (interpreted as glycogenolysis) during post-absorptive conditions and at time 0 after administration of both drugs. After oral glucose tolerance test, the incremental areas of blood glucose and insulin were significantly decreased by 18 and 19% after acipimox compared to placebo. In addition, the ratio between the incremental area of forearm muscle glucose uptake and the insulin levels was significantly increased by 45% during acipimox compared to placebo administration. Glucose oxidation and non-oxidative glycolysis were significantly higher while lipid oxidation was significantly lower after acipimox than after placebo. In conclusion, our study found that in lean non-insulin-dependent diabetic subjects, an acute decrease in non-esterified fatty acid levels improves glucose tolerance, muscle glucose uptake, glucose oxidation and non-oxidative glycolysis, but is unable to normalize glucose storage.