Prediabetes as a toxic environment for the initiation of microvascular and macrovascular complications

Prediabetes is a state characterized by impaired fasting glucose or impaired glucose tolerance. Evidence is increasingly demonstrating that prediabetes is a toxic state, in addition to being a harbinger of future development of diabetes mellitus. This minireview discusses the pathophysiology and clinical significance of prediabetes, and approach to its management, in the context of the worldwide diabetes epidemic. The pathophysiologic defects underlying prediabetes include insulin resistance, β cell dysfunction, increased lipolysis, inflammation, suboptimal incretin effect, and possibly hepatic glucose overproduction. Recent studies have revealed that the long-term complications of diabetes may manifest in some people with prediabetes; these complications include classical microvascular and macrovascular disorders, and our discussion explores the role of glycemia in their development. Finally, landmark intervention studies in prediabetes, including lifestyle modification and pharmacologic treatment, are reviewed.

Hyperglycemic, high anion-gap metabolic acidosis in patients receiving SGLT-2 inhibitors for diabetes management

Sodium-glucose cotransporter-2 inhibitors (SGLT-2i) are a class of antidiabetic medications that improve glycemic control via inhibiting the reabsorption of filtered glucose and are approved for use in type 2 diabetes (T2DM). These drugs have recently been associated with euglycemic diabetic ketoacidosis (DKA). An increasing number of cases of SGLT-2i-associated DKA have occurred in patients with T2DM. Herein, we describe five episodes of hyperglycemic DKA in four type 2 diabetes patients receiving SGLT-2i therapy. Risk for ketoacidosis in our case series was mediated predominately by reduction of insulin dose and insulinopenia. None of the patients reported a history of low carbohydrate diet or alcohol use, and all but one patient had negative glutamic acid decarboxylase antibodies. Resolution of DKA in SGLT-2i treated patients took longer than for T1DM patients with DKA based on literature data. The mechanisms by which SGLT-2i are associated with ketoacidosis are not fully understood and likely involve hyperglucagonemia and other factors. Further studies are needed to elucidate the precise mechanism.

Insulin-sensitive and insulin-resistant obese and non-obese phenotypes: role in prediction of incident pre-diabetes in a longitudinal biracial cohort

OBJECTIVE

We measured insulin sensitivity with euglycemic clamp (Si-clamp) in initially normoglycemic African Americans (AA) and European Americans (EA), to probe the existence of subphenotypes of obesity and leanness, and their impact on incident dysglycemia during longitudinal follow-up.

RESEARCH DESIGN AND METHODS

320 healthy subjects (176 AA, 144 EA; mean age 44.2±10.6 years) underwent baseline assessments, including Si-clamp and homeostasis model of insulin resistance (HOMA-IR) and were stratified into: insulin-resistant obese (IRO) (body mass index (BMI) >30 kg/m², Si-clamp <0.1, HOMA-IR >2.5); insulin-sensitive obesity (ISO) (BMI >30 kg/m², Si-clamp >0.1, HOMA-IR <2.5); insulin-resistant non-obese (IRN) (BMI <28 kg/m², Si-clamp <0.1, HOMA-IR >2.5); insulin-sensitive non-obese (ISN) (BMI <28 kg/m², Si-clamp >0.1, HOMA-IR <2.5). Outcome measures were cardiometabolic risks and incident pre-diabetes/type 2 diabetes (T2D) during 5.5 years.

RESULTS

Compared with IRO, subjects with ISO had lower abdominal fat, triglycerides and high-sensitivity C reactive protein and higher adiponectin (p=0.015 to <0.0001). IRN subjects had higher cardiometabolic risk markers than ISN (p=0.03 to <0.0001). During 5.5-year follow-up, incident pre-diabetes/T2D was lower in ISO (31.3% vs 48.7%) among obese subjects and higher in IRN (47.1% vs. 26.0%) among non-obese subjects (p=0.0024). Kaplan-Meier analysis showed significantly different pre-diabetes/T2D survival probabilities across insulin sensitivity/adiposity phenotypes (p=0.0001).

CONCLUSIONS

Insulin sensitivity predicts ~40% decrease in the relative risk of incident pre-diabetes/T2D among obese persons, whereas insulin resistance predicts ~80% increased risk among non-obese persons. This is the first documentation of healthy and unhealthy phenotypes of obesity and leanness in a prospective biracial cohort, using rigorous measurement of insulin sensitivity.

Combination of Recreational Soccer and Caloric Restricted Diet Reduces Markers of Protein Catabolism and Cardiovascular Risk in Patients with Type 2 Diabetes

BACKGROUND

Moderate calorie-restricted diets and exercise training prevent loss of lean mass and cardiovascular risk. Because adherence to routine exercise recommendation is generally poor, we utilized recreational soccer training as a novel therapeutic exercise intervention in type 2 diabetes (T2D) patients.

OBJECTIVE

We compared the effects of acute and chronic soccer training plus calorie-restricted diet on protein catabolism and cardiovascular risk markers in T2D.

DESIGN, SETTING AND SUBJECTS

Fifty-one T2D patients (61.1±6.4 years, 29 females: 22 males) were randomly allocated to the soccer+diet-group (SDG) or to the diet-group (DG). The 40-min soccer sessions were held 3 times per week for 12 weeks.

RESULTS

Nineteen participants attended 100% of scheduled soccer sessions, and none suffered any injuries. The SDG group showed higher levels of growth hormone (GH), free fatty acids and ammonia compared with DG. After 12 weeks, insulin-like growth factor binding protein (IGFPB)-3 and glucose levels were lower in SDG, whereas insulin-like growth factor (IGF)-1/ IGFBP-3 ratio increased in both groups. After the last training session, an increase in IGF-1/IGFBP-3 and attenuation in ammonia levels were suggestive of lower muscle protein catabolism.

CONCLUSIONS

Recreational soccer training was popular and safe, and was associated with decreased plasma glucose and IGFBP-3 levels, decreased ammoniagenesis, and increased lipolytic activity and IGF-1/IGFBP-3 ratio, all indicative of attenuated catabolism.

Plasma lipid levels predict dysglycemia in a biracial cohort of nondiabetic subjects: Potential mechanisms

Dyslipidemia and dysglycemia are etiologically associated, but the direction, chronology, and mechanisms of the association are not fully understood. We, therefore, analyzed data from 335 healthy adults (184 black, 151 white) enrolled in the Pathobiology of Prediabetes in A Biracial Cohort study. Subjects underwent oral glucose tolerance test (OGTT) and were enrolled if they had normal fasting and 2-h plasma glucose levels. Assessments during year 1 included anthropometry, fasting lipid profile, insulin sensitivity, and insulin secretion. Thereafter, OGTT was assessed annually for 5.5 years. The primary outcome was occurrence of prediabetes (impaired fasting glucose or impaired glucose tolerance) or diabetes. During a mean follow-up of 2.62 years, 110 participants (32.8%) developed prediabetes (N = 100) or diabetes (N = 10). In multivariate logistic regression models, higher baseline low-density lipoprotein (LDL) cholesterol and triglyceride levels and lower HDL cholesterol levels significantly increased the risk of incident prediabetes. The combined relative risk (95% confidence interval [CI]) of prediabetes for participants with lower baseline HDL cholesterol (10th vs. 90th percentile), higher LDL cholesterol (90th vs. 10th percentile) and high triglycerides levels (90th vs. 10th percentile) was 4.12 (95% CI 1.61-10.56), P = 0.0032. At baseline, lipid values showed significant associations with measures of adiposity, glycemia, insulin sensitivity, and secretion. In both ethnic groups, waist circumference correlated positively with triglycerides and inversely with HDL cholesterol levels (P = 0.0004-<0.0001); fasting plasma glucose correlated positively with triglycerides and LDL cholesterol levels and inversely with HDL cholesterol levels (P = 0.006-<0.0001); insulin sensitivity correlated positively with HDL cholesterol and inversely with triglyceride levels (P < 0.0001), and insulin secretion correlated positively with triglycerides (P = 0.01) and inversely with HDL cholesterol (P < 0.0001). We conclude that a baseline lipidemic signature identifies normoglycemic individuals at high risk for future glycemic progression, via congruent associations with adiposity and glucoregulatory mechanisms. These findings suggest that early lifestyle intervention could ameliorate progressive dyslipidemia and dysglycemia.

Pioglitazone Prevents Diabetes in Patients With Insulin Resistance and Cerebrovascular Disease

OBJECTIVE

The Insulin Resistance Intervention after Stroke (IRIS) trial recently found that pioglitazone reduced risk for stroke and myocardial infarction in patients with insulin resistance but without diabetes who had had a recent ischemic stroke or transient ischemic attack (TIA). This report provides detailed results on the metabolic effects of pioglitazone and the trial's prespecified secondary aim of diabetes prevention.

RESEARCH DESIGN AND METHODS

A total of 3,876 patients with recent ischemic stroke or TIA, no history of diabetes, fasting plasma glucose (FPG) <126 mg/dL, and insulin resistance by homeostasis model assessment of insulin resistance (HOMA-IR) score >3.0 were randomly assigned to pioglitazone or placebo. Surveillance for diabetes onset during the trial was accomplished by periodic interviews and annual FPG testing.

RESULTS

At baseline, the mean FPG, HbA1c, insulin, and HOMA-IR were 98.2 mg/dL (5.46 mmol/L), 5.8% (40 mmol/mol), 22.4 μIU/mL, and 5.4, respectively. After 1 year, mean HOMA-IR and FPG decreased to 4.1 and 95.1 mg/dL (5.28 mmol/L) in the pioglitazone group and rose to 5.7 and 99.7 mg/dL (5.54 mmol/L), in the placebo group (all P < 0.0001). Over a median follow-up of 4.8 years, diabetes developed in 73 (3.8%) participants assigned to pioglitazone compared with 149 (7.7%) assigned to placebo (hazard ratio [HR] 0.48 [95% CI 0.33-0.69]; P < 0.0001). This effect was predominately driven by those with initial impaired fasting glucose (FPG >100 mg/dL [5.6 mmol/L]; HR 0.41 [95% CI 0.30-0.57]) or elevated HbA1c (>5.7% [39 mmol/mol]; HR 0.46 [0.34-0.62]).

CONCLUSIONS

Among patients with insulin resistance but without diabetes who had had a recent ischemic stroke or TIA, pioglitazone decreased the risk of diabetes while also reducing the risk of subsequent ischemic events. Pioglitazone is the first medication shown to prevent both progression to diabetes and major cardiovascular events as prespecified outcomes in a single trial.

CONSENSUS STATEMENT BY THE AMERICAN ASSOCIATION OF CLINICAL ENDOCRINOLOGISTS AND AMERICAN COLLEGE OF ENDOCRINOLOGY ON THE COMPREHENSIVE TYPE 2 DIABETES MANAGEMENT ALGORITHM--2015 EXECUTIVE SUMMARY

This document represents the official position of the American Association of Clinical Endocrinologists and the American College of Endocrinology. Where there were no randomized controlled trials or specific U.S. FDA labeling for issues in clinical practice, the participating clinical experts utilized their judgment and experience. Every effort was made to achieve consensus among the committee members. Position statements are meant to provide guidance, but they are not to be considered prescriptive for any individual patient and cannot replace the judgment of a clinician.

2015 Presidential Address: 75 Years of Battling Diabetes--Our Global Challenge

This address was delivered by Samuel Dagogo-Jack, MD, President, Medicine & Science, of the American Diabetes Association (ADA), at the Association's 75th Scientific Sessions in Boston, MA, on 7 June 2015. Dr. Dagogo-Jack is a professor of medicine and the director of the Division of Endocrinology, Diabetes and Metabolism and the director of the Clinical Research Center at The University of Tennessee Health Science Center, Memphis, TN, where he holds the A.C. Mullins Endowed Chair in Translational Research. He has been an ADA volunteer since 1991 and has served on several national committees and chaired the Association's Research Grant Review Committee. At the local level, he has served on community leadership boards in St. Louis, MO, and Tennessee. A physician-scientist, Dr. Dagogo-Jack's current research focuses on the interaction of genetic and environmental factors in the prediction and prevention of prediabetes, diabetes, and diabetes complications. He is the principal investigator of the Pathobiology of Prediabetes in a Biracial Cohort (POP-ABC) study and also directs The University of Tennessee site for the Diabetes Control and Complications Trial/Epidemiology of Diabetes Interventions and Complications (DCCT/EDIC) and the Diabetes Prevention Program (DPP)/DPP Outcomes Study (DPPOS). Dr. Dagogo-Jack earned his medical and research doctorate degrees from the University of Ibadan College of Medicine in Nigeria, holds a master's of science from the University of Newcastle upon Tyne in England, and completed his postdoctoral fellowship training in metabolism at the Washington University School of Medicine in St. Louis in Missouri. A board-certified endocrinologist, Dr. Dagogo-Jack has been elected to the Association of American Physicians and is the 2015 recipient of the Banting Medal for Leadership from the ADA. The ADA and Diabetes Care thank Dr. Dagogo-Jack for his outstanding leadership and service to the Association.

Adiponectin levels predict prediabetes risk: the Pathobiology of Prediabetes in A Biracial Cohort (POP-ABC) study

BACKGROUND

Adiponectin levels display ethnic disparities, and are inversely associated with the risk of type 2 diabetes (T2DM). However, the association of adiponectin with prediabetes risk in diverse populations has not been well-studied. Here, we assessed baseline adiponectin levels in relation to incident prediabetes in a longitudinal biracial cohort.

RESEARCH DESIGN AND METHODS

The Pathobiology of Prediabetes in A Biracial Cohort study followed non-diabetic offspring of parents with T2DM for the occurrence of prediabetes, defined as impaired fasting glucose and/or impaired glucose tolerance. Assessments at enrollment and during follow-up included a 75 g oral glucose tolerance test, anthropometry, biochemistries (including fasting insulin and adiponectin levels), insulin sensitivity and insulin secretion. Logistic regression was used to evaluate the contribution of adiponectin to risk of progression to prediabetes.

RESULTS

Among the 333 study participants (mean (SD) age 44.2 (10.6) year), 151(45.3%) were white and 182 (54.8%) were black. During approximately 5.5 (mean 2.62) years of follow-up, 110 participants (33%) progressed to prediabetes (N=100) or T2DM (N=10), and 223 participants (67%) were non-progressors. The mean cohort adiponectin level was 9.41+5.30 μg/mL (range 3.1-45.8 μg/mL); values were higher in women than men (10.3+5.67 μg/mL vs 7.27+3.41 μg/mL, p<0.0001) and in white than black offspring (10.7+5.44 μg/mL vs 8.34+4.95 μg/mL, p<0.0001). Adiponectin levels correlated inversely with adiposity and glycemia, and positively with insulin sensitivity and high-density lipoprotein cholesterol levels. Baseline adiponectin strongly predicted incident prediabetes: the HR for prediabetes per 1 SD (approximately 5 μg/mL) higher baseline adiponectin was 0.48 (95% CI 0.27 to 0.86, p=0.013).

CONCLUSIONS

Among healthy white and black adults with parental history of T2DM, adiponectin level is a powerful risk marker of incident prediabetes. Thus, the well-known association of adiponectin with diabetes risk is evident at a much earlier stage in pathogenesis, during transition from normoglycemia to prediabetes.

Philip E. Cryer, MD: Seminal Contributions to the Understanding of Hypoglycemia and Glucose Counterregulation and the Discovery of HAAF (Cryer Syndrome)

Optimized glycemic control prevents and slows the progression of long-term complications in patients with type 1 and type 2 diabetes. In healthy individuals, a decrease in plasma glucose below the physiological range triggers defensive counterregulatory responses that restore euglycemia. Many individuals with diabetes harbor defects in their defenses against hypoglycemia, making iatrogenic hypoglycemia the Achilles heel of glycemic control. This Profile in Progress focuses on the seminal contributions of Philip E. Cryer, MD, to our understanding of hypoglycemia and glucose counterregulation, particularly his discovery of the syndrome of hypoglycemia-associated autonomic failure (HAAF).

Potential Health Implications of Medication Therapy Management Eligibility Criteria in the Patient Protection and Affordable Care Act Across Racial and Ethnic Groups

BACKGROUND

The Medicare Prescription Drug, Improvement, and Modernization Act requires Part D plans to establish programs to provide medication therapy management (MTM) services starting from 2006. MTM services have been found to improve patient outcomes from pharmacotherapy, reduce emergency room visits and hospitalizations, and reduce health care costs in a cost-effective fashion. However, previous research found that non-Hispanic blacks (blacks) and Hispanics may be less likely to be eligible for MTM services than non-Hispanic whites (whites) among the Medicare population, according to current Medicare MTM eligibility criteria. This finding is because Medicare MTM eligibility criteria are predominantly based on medication use and costs, and blacks and Hispanics tend to use fewer prescription medications and incur lower prescription medication costs. The Patient Protection and Affordable Care Act (PPACA) laid out a set of MTM eligibility criteria for eligible entities to target patients for MTM services: "(1) take 4 or more prescribed medications ...; (2) take any 'high risk' medications; (3) have 2 or more chronic diseases ... or (4) have undergone a transition of care, or other factors ... that are likely to create a high risk of medication-related problems."

OBJECTIVES

To (a) examine racial/ethnic disparities in meeting the eligibility criteria for MTM services in PPACA among the Medicare population and (b) determine whether there would be greater disparities in health and economic outcomes among MTM-ineligible than MTM-eligible groups.

METHODS

This was a retrospective cross-sectional analysis of the Medicare Current Beneficiaries Survey (2007-2008). To determine medication characteristics, the U.S. Food and Drug Administration's Electronic Orange Book was also used. Proportions of the population eligible for MTM services based on PPACA MTM eligibility criteria were compared across racial and ethnic groups using a chi-square test; a logistic regression model was used to adjust for population sociodemographic and health characteristics. Health and economic outcomes examined included health status (self-perceived good health status, number of chronic diseases, activities of daily living [ADLs], and instrumental activities of daily living [IADLs]), health services utilization and costs (physician visits, emergency room visits, and total health care costs), and medication use patterns (generic dispensing ratio). To determine difference in disparities across MTM eligibility categories, difference-in-differences regressions of various functional forms were employed, depending on the nature of the dependent variables. Interaction terms between the dummy variables for minority groups (e.g., blacks or Hispanics) and MTM eligibility were included to test whether disparity patterns varied between MTM-ineligible and MTM-eligible individuals.

RESULTS

The sample consisted of 12,966 Medicare beneficiaries, of which 11,161 were white, 930 were black, and 875 were Hispanic. Of the study sample, 9,992 whites (86.4%), 825 blacks (86.3%), and 733 Hispanics (80.6%) were eligible for MTM. The difference between whites and Hispanics was significant (P  less than  0.050), and the difference between whites and blacks was not significant (P  greater than 0.050). In multivariate analyses, significant disparity in eligibility for MTM services was found only between Hispanics and whites (odds ratio [OR] = 0.59; 95% CI = 0.43-0.82) but not between blacks and whites (OR = 0.78; 95% CI = 0.55-1.09). Disparities were greater among the MTM-ineligible than the MTM-eligible populations in self-perceived health status, ADLs, and IADLs for both blacks and Hispanics compared with whites. When analyzing the number of chronic conditions, the number and costs of physician visits, and total health care costs, the authors of this study found lower racial and ethnic disparities among the ineligible population than the eligible population.

CONCLUSIONS

Hispanics are significantly less likely than whites to qualify for MTM among the Medicare population, according to MTM eligibility criteria stipulated in the PPACA. PPACA MTM eligibility criteria may aggravate existing racial and ethnic disparities in health status but may remediate racial and ethnic disparities in health services utilization. Alternative MTM eligibility criteria other than PPACA MTM eligibility criteria may be needed to improve the efficiency and equity of access to Medicare Part D MTM programs.

Dietary habits and leisure-time physical activity in relation to adiposity, dyslipidemia, and incident dysglycemia in the pathobiology of prediabetes in a biracial cohort study

BACKGROUND

Dietary and exercise data are frequently recorded in clinical research, but their correlation with metabolic measures needs further evaluation.

OBJECTIVE

We examined the association of food and exercise habits with body size, lipid profile, and glycemia in a prospective biracial cohort.

METHODS

The Pathobiology of Prediabetes in A Biracial Cohort study followed initially normoglycemic offspring of parents with type 2 diabetes (T2DM) for the occurrence of incident prediabetes, defined as impaired fasting glucose (IFG) and/or impaired glucose tolerance (IGT). At enrollment, participants underwent a 75-gram OGTT, anthropometry, measurement of fasting lipids, insulin, and body fat (DEXA), and completed the Food Habits Questionnaire (FHQ), and Modifiable Activity Questionnaire (MAQ). We assessed the relationship between FHQ and MAQ scores and adiposity, cardiometabolic measures, and incident dysglycemia.

RESULTS

Among our cohort of 338 subjects (188 black, 150 white; mean age {±SD} 45.2±10.2 years, BMI 30.3±7.2 kg/m(2)), FHQ and MAQ scores were individually correlated with BMI (r=0.14, -0.12; P=0.01, 0.03) and waist circumference (r=0.19, -0.11; P=0.004, 0.05). Diet-adjusted leisure activity (MAQ/FHQ) was significantly correlated with total body fat (r=-0.20, P=0.0007), trunk fat (r=-0.20, P=0.0006), and serum triglycerides (r=-0.17, P=0.003) and HDL cholesterol (r=0.11, P=0.04) levels. During 5.5 years of follow-up, 111 subjects (Progressors) developed prediabetes (n=101) or diabetes (n=10) and 227 remained normoglycemic (Non-progressors). Age, BMI, MAQ and MAQ/FHQ values were significant predictors of incident prediabetes/diabetes. Progressors reported similar dietary habits (FHQ score 2.57±0.49 vs. 2.57±0.53) but 30% lower physical activity (MAQ score 15.2±20.5 vs. 22.3±30.5 MET-hr/wk, P=0.015) compared with non-progressors.

CONCLUSIONS

Among African-American and Caucasian offspring of parents with T2DM, self-reported dietary and exercise habits correlated with measures of adiposity and dyslipidemia; however, physical activity, but not dietary recall, significantly predicted incident dysglycemia during 5.5 years of follow-up.

Effects of medicare part d on disparity implications of medication therapy management eligibility criteria

BACKGROUND

Previous studies have shown that there were greater racial and ethnic disparities among individuals who were ineligible for medication therapy management (MTM) services than among MTM-eligible individuals before the implementation of Medicare Part D in 2006.

OBJECTIVE

To determine whether the implementation of Medicare Part D in 2006 correlates to changes in racial and ethnic disparities among MTM-ineligible and MTM-eligible beneficiaries.

METHODS

Data from the Medicare Current Beneficiary Survey were analyzed in this retrospective observational analysis. To examine potential racial and ethnic disparities, non-Hispanic whites were compared with non-Hispanic blacks and Hispanics. Three aspects of disparities were analyzed, including health status, health services utilization and costs, and medication utilization patterns. A generalized difference-in-differences analysis was used to examine the changes in difference in disparities between MTM-ineligible and MTM-eligible individuals from 2004-2005 to 2007-2008 relative to changes from 2001-2002 and 2004-2005. Various multivariate regressions were used based on the types of dependent variables. A main analysis and several sensitivity analyses were conducted to represent the ranges of MTM eligibility thresholds used by Medicare Part D plans in 2010.

RESULTS

The main analysis showed that Part D implementation was not associated with reductions in greater racial and ethnic disparities among MTM-ineligible than MTM-eligible Medicare beneficiaries. The main analysis suggests that after Part D implementation, Medicare MTM eligibility criteria may not consistently improve the existing racial and ethnic disparities in health status, health services utilization and costs, and medication utilization. By contrast, several sensitivity analyses showed that Part D implementation did correlate with a significant reduction in greater racial disparities among the MTM-ineligible group than the MTM-eligible group in activities of daily living and in instrumental activities of daily living. Part D implementation may be also associated with a reduction in greater ethnic disparities among the MTM-ineligible group than the MTM-eligible groups in the costs of physician visits.

CONCLUSION

Part D implementation was not associated with consistent reductions in the disparity implications of the Medicare MTM eligibility criteria. The main analysis showed that Part D implementation was not associated with a reduction in disparities associated with MTM eligibility, although several sensitivity analyses did show reductions in disparities in specific aspects. Future research should explore alternative Medicare MTM eligibility criteria to eliminate racial and ethnic disparities among the Medicare population.

Glucoregulatory function among African Americans and European Americans with normal or pre-diabetic hemoglobin A1c levels

OBJECTIVE

A hemoglobin (Hb) A1c range of 5.7%-6.4% has been recommended for the diagnosis of prediabetes. To determine the significance of such "prediabetic" HbA1c levels, we compared glucoregulatory function in persons with HbA1c levels of 5.7%-6.4% and those with HbA1c<5.7%.

METHODS

We studied 280 nondiabetic adults (142 black, 138 white; mean (±SD) age 44.2±10.6 years). Each subject underwent clinical assessment, blood sampling for HbA1c measurement, and a 75-g oral glucose tolerance test at baseline. Additional assessments during subsequent outpatient visits included insulin sensitivity, using homeostasis model assessment (HOMA)-IR and the hyperinsulinemic euglycemic clamp; insulin secretion, using HOMA-B and frequently samples intravenous glucose tolerance test (FSIVGTT) and disposition index (DI); and measurement of fat mass, using DXA.

RESULTS

Compared to subjects with HbA1c<5.7%, persons with HbA1c levels of 5.7%-6.4% were older, and had higher body mass index (BMI) and insulin secretion but similar insulin sensitivity. When the two groups were matched in age and BMI, persons with HbA1c 5.7%-6.4% were indistinguishable from those with HbA1c <5.7% with regard to all measures of glycemia and glucoregulatory function.

CONCLUSIONS

Unlike glucose-defined prediabetes status, an HbA1c range of 5.7%-6.4% does not reliably identify individuals with impaired insulin action or secretion, the classical defects underlying the pathophysiology of prediabetes. Thus, HbA1c cannot validly replace blood glucose measurement in the diagnosis of prediabetes. If utilized as a screening test due to convenience, aberrant HbA1c values should be corroborated with blood glucose measurement before therapeutic intervention.

Lack of racial disparity in incident prediabetes and glycemic progression among black and white offspring of parents with type 2 diabetes: the pathobiology of prediabetes in a biracial cohort (POP-ABC) study

BACKGROUND

Although the incidence of type 2 diabetes (T2D) among persons with prediabetes is well known (∼10%/y), the incidence of prediabetes among normoglycemic persons is unclear. Also, in the Diabetes Prevention Program, no racial/ethnic differences were seen in diabetes incidence, whereas marked racial/ethnic disparities are reported in the prevalence of T2D. We aimed to obtain estimates of incident prediabetes and determine whether racial disparities manifest during transition to prediabetes.

DESIGN AND METHODS

We enrolled 376 (217 black, 159 white) nondiabetic offspring of parents with T2D (mean age 44.2 y) and followed them up quarterly for 5.5 years. Assessments included anthropometry, body composition, oral glucose tolerance test, biochemistries, energy expenditure, insulin sensitivity, and insulin secretion. The primary outcome was progression to impaired fasting glucose and/or impaired glucose tolerance (or diabetes).

RESULTS

Of 343 participants with evaluable data, 101 subjects (49 white, 52 black) developed prediabetes, and 10 (4 white, 6 black) developed diabetes during a mean follow-up of 2.62 years. There was no significant racial difference in the cumulative incidence of prediabetes (32.7% white, 30% black) or combined prediabetes/diabetes (35% white, 30% black). Significant predictors of prediabetes included age, gender, trunk fat, 2-hour postload glucose (2hrPG), insulin sensitivity, and insulin secretion. In a Cox proportional-hazards model, with adjustment for age and sex, the 2hrPG and abdominal obesity were independent predictors of incident prediabetes/diabetes [relative hazards (95% confidence interval [CI]) for the 90th vs 10th percentile: trunk fat mass 2.90 (95% CI 1.74-4.82), P < .0001; 2hrPG 2.54 (95% CI 1.46-4.40), P = .0009]. Having the trunk fat mass and the 2hrPG at the 90th percentile conferred a 7-fold hazard of prediabetes compared with persons at the 10th percentile for both measures.

CONCLUSION

Black and white offspring of parents with type 2 diabetes develop prediabetes at a similar high rate of approximately 11% per year. Therefore, close surveillance, with prompt intervention to prevent dysglycemia, is warranted in persons with parental diabetes.

Potential effects of racial and ethnic disparities in meeting Medicare medication therapy management eligibility criteria

OBJECTIVE

Medication therapy management (MTM) has the potential to play an instrumental role in reducing racial and ethnic disparities in health care. However, previous research has found that Blacks and Hispanics are less likely to be eligible for MTM. The purpose of the current study was to examine the potential effects of MTM eligibility criteria on racial and ethnic disparities in health outcomes.

METHODS

The current study is a retrospective cross-sectional analysis of the Medicare Current Beneficiary Survey Cost and Use files for the years 2007 and 2008. A difference-in-differences model was used to compare disparities in outcomes between ineligible and eligible beneficiaries according to MTM eligibility criteria in 2010. This was achieved by including in regression models interaction terms between dummy variables for Blacks/Hispanics and MTM eligibility criteria. Interaction terms were interpreted on both multiplicative and additive terms. Various regression models were used depending on the types of variables.

KEY FINDINGS

Whites were more likely to report self-perceived good health status than Blacks and Hispanics among both MTM-eligible and MTM-ineligible populations. Disparities were greater among MTM-ineligible than MTM-eligible populations (e.g., on additive term, difference in odds=1.94 and P<0.01 for Whites and Blacks; difference in odds=2.86 and P<0.01 for Whites and Hispanics). A few other measures also exhibited significant patterns.

CONCLUSIONS

MTM eligibility criteria may exacerbate racial and ethnic disparities in health status and some measures of health services utilizations and costs and medication utilization. Future research should examine strategies to remediate the effects of MTM eligibility criteria on disparities.