Non-traditional risk factors are important contributors to the racial disparity in diabetes risk: the atherosclerosis risk in communities study

Differences in substrate metabolism between African American and Caucasian infants: evidence from mesenchymal stem cells

Type 2 diabetes is more prevalent in African American (AA) than Caucasian (C) adults. Furthermore, differential substrate utilization has been observed between AA and C adults, but data regarding metabolic differences between races at birth remains scarce. The purpose of the present study was to determine if there are racial differences in substrate metabolism evident at birth using a mesenchymal stem cells (MSCs) collected from offspring umbilical cords. Using radio-labeled tracers, MSCs from offspring of AA and C mothers were tested for glucose and fatty acid metabolism in the undifferentiated state and while undergoing myogenesis in vitro. Undifferentiated MSCs from AA exhibited greater partitioning of glucose toward nonoxidized glucose metabolites. In the myogenic state, AA displayed higher glucose oxidation, but similar fatty acid oxidation rates. In the presence of both glucose and palmitate, but not palmitate only, AA exhibit a higher rate of incomplete fatty acid oxidation evident by a greater production of acid-soluble metabolites. Myogenic differentiation of MSCs elicits an increase in glucose oxidation in AA, but not in C. Together, these data suggest that metabolic differences between AA and C races exist at birth.NEW & NOTEWORTHY African Americans, when compared with Caucasians, display greater insulin resistance in skeletal muscle. Differences in substrate utilization have been proposed as a factor for this health disparity; however, it remains unknown how early these differences manifest. Using infant umbilical cord-derived mesenchymal stem cells, we tested for in vitro glucose and fatty acid oxidation differences. Myogenically differentiated MSCs from African American offspring display higher rates of glucose oxidation and incomplete fatty acid oxidation.

Multi-dimensional characterization of prediabetes in the Project Baseline Health Study

Background

We examined multi-dimensional clinical and laboratory data in participants with normoglycemia, prediabetes, and diabetes to identify characteristics of prediabetes and predictors of progression from prediabetes to diabetes or reversion to no diabetes.

Methods

The Project Baseline Health Study (PBHS) is a multi-site prospective cohort study of 2502 adults that conducted deep clinical phenotyping through imaging, laboratory tests, clinical assessments, medical history, personal devices, and surveys. Participants were classified by diabetes status (diabetes [DM], prediabetes [preDM], or no diabetes [noDM]) at each visit based on glucose, HbA1c, medications, and self-report. Principal component analysis (PCA) was performed to create factors that were compared across groups cross-sectionally using linear models. Logistic regression was used to identify factors associated with progression from preDM to DM and for reversion from preDM to noDM.

Results

At enrollment, 1605 participants had noDM; 544 had preDM; and 352 had DM. Over 4 years of follow-up, 52 participants with preDM developed DM and 153 participants reverted to noDM. PCA identified 33 factors composed of clusters of clinical variables; these were tested along with eight individual variables identified a priori as being of interest. Six PCA factors and six a priori variables significantly differed between noDM and both preDM and DM after false discovery rate adjustment for multiple comparisons (q < 0.05). Of these, two factors (one comprising glucose measures and one of anthropometry and physical function) demonstrated monotonic/graded relationships across the groups, as did three a priori variables: ASCVD risk, coronary artery calcium, and triglycerides (q < 10^–21 for all). Four factors were significantly different between preDM and noDM, but concordant or similar between DM and preDM: red blood cell indices (q = 8 × 10^-10), lung function (q = 2 × 10^-6), risks of chronic diseases (q = 7 × 10^-4), and cardiac function (q = 0.001), along with a priori variables of diastolic function (q = 1 × 10^-10), sleep efficiency (q = 9 × 10^-6) and sleep time (q = 6 × 10^-5). Two factors were associated with progression from prediabetes to DM: anthropometry and physical function (OR [95% CI]: 0.6 [0.5, 0.9], q = 0.04), and heart failure and c-reactive protein (OR [95% CI]: 1.4 [1.1, 1.7], q = 0.02). The anthropometry and physical function factor was also associated with reversion from prediabetes to noDM: (OR [95% CI]: 1.9 [1.4, 2.7], q = 0.02) along with a factor of white blood cell indices (OR [95% CI]: 0.6 [0.4, 0.8], q = 0.02), and the a priori variables ASCVD risk score (OR [95% CI]: 0.7 [0.6, 0.9] for each 0.1 increase in ASCVD score, q = 0.02) and triglycerides (OR [95% CI]: 0.9 [0.8, 1.0] for each 25 mg/dl increase, q = 0.05).

Conclusions

PBHS participants with preDM demonstrated pathophysiologic changes in cardiac, pulmonary, and hematology measures and declines in physical function and sleep measures that precede DM; some changes predicted an increased risk of progression to DM. A factor with measures of anthropometry and physical function was the most important factor associated with progression to DM and reversion to noDM. Future studies may determine whether these changes elucidate pathways of progression to DM and related complications and whether they can be used to identify individuals at higher risk of progression to DM for targeted preventive interventions.

Trial registration ClinicalTrials.gov NCT03154346

Supplementary Information

The online version contains supplementary material available at 10.1186/s12933-022-01565-x.

Reticulocalbin 2 as a Potential Biomarker and Therapeutic Target for Atherosclerosis

Vascular inflammation initiated by oxidized lipoproteins drives initiation, progression, and even rupture of atherosclerotic plaques. Yet, to date, no biomarker is directly linked to oxidized lipid-induced vascular inflammation. Reticulocalbin 2 (RCN2) is a key regulator of basal and oxidized lipid-induced cytokine production in arterial wall cells. We evaluated the potential of circulating RCN2 to identify subjects with or at risk of developing atherosclerosis. Immunohistochemical analysis revealed abundant RCN2 expression in the endothelium and adventitia of normal arteries and in atherosclerotic lesions of both humans and mice. Atherosclerosis-susceptible C57BL/6 (B6) mice had higher plasma Rcn2 levels than resistant C3H mice. High-fat diet feeding raised plasma Rcn2 levels of both strains. In humans, patients with coronary artery disease (CAD) or peripheral artery disease (PAD) showed elevated serum RCN2 levels compared to healthy controls. In a cohort of 92 CAD patients, serum RCN2 exhibited a significant inverse correlation with HDL cholesterol and K+ levels and a trend toward association with white blood cell account, Na+, statin treatment, and diastolic blood pressure. HDL treatment suppressed Rcn2 expression in endothelial cells. This study suggests that circulating RCN2 is a potential non-invasive biomarker for identifying individuals with atherosclerosis and HDL protects against atherosclerosis by downregulation of RCN2 expression in endothelial cells.

Vitamin D Deficiency in Patients with Diabetes in French Guiana: Epidemiology and Relation with Microvascular and Macrovascular Complications

Vitamin D (VD) insufficiency is common among patients with diabetes in French Guiana. The study aimed to evaluate the prevalence of VD deficiency in the different type of diabetes encountered and to analyze the relationship between VD deficiency and diabetes complications. Methods: An observational study was conducted between May 2019 and May 2020 in French Guiana, based on data from the CODIAM study (Diabetes Cohort in French Amazonia), describing the characteristics of patients with diabetes mellitus. Among 600 patients enrolled with diabetes, 361 had an available VD assay. Results: The mean 25(OH)VD (hydroxycalciferol) level was 27.9 ng/mL. The level of VD was inversely proportional to the HbA1c (glycated hemoglobin) level. Patients with angina pectoris had a greater proportion of deficiencies VD < 20 ng/mL than those without angina. By contrast, patients with retinopathy had higher vitamin D concentrations than those without retinopathy. There was no association between vitamin D and arteriopathy, stroke, nephropathy and polyneuropathy. VD deficiency was more frequent in women, and in patients with a high school education. Conclusion: The prevalence of VD deficiency was high in patients with diabetes in French Guiana, emphasizing the importance of VD supplementation.

Disparities in cardio metabolic risk between Black and White women with polycystic ovary syndrome: a systematic review and meta-analysis

OBJECTIVE

We conducted a systematic review and meta-analysis to summarize and quantitatively pool evidence on cardiometabolic health disparities between Black and White women with polycystic ovary syndrome in the United States in response to the call for further delineation of these disparities in the international evidence-based guideline for the assessment and management of polycystic ovary syndrome.

DATA SOURCES

Databases of MEDLINE, Web of Science, and Scopus were searched initially through March 05, 2020, and confirmed on September 11, 2020.

STUDY ELIGIBILITY CRITERIA

Observational studies documenting cardiometabolic risk profile (glucoregulatory, lipid profile, anthropometric, and blood pressure status) in Black and White women with polycystic ovary syndrome were included. Studies on children (<17 years old) and pregnant or menopausal-aged women (>50 years) were excluded. The primary outcome was fasting glucose. Furthermore, data on major cardiovascular events (stroke, coronary heart disease, heart failure) and mortality rate (cardiovascular death, total mortality) were evaluated.

METHODS

Data were pooled by random-effects models and expressed as mean differences and 95% confidence intervals. Studies were weighted based on the inverse of the variance. Heterogeneity was evaluated by Cochran Q and I2 statistics. Study methodologic quality was assessed by the Newcastle-Ottawa scale.

RESULTS

A total of 11 studies (N=2851 [652 Black and 2199 White]) evaluated cardiometabolic risk profile and all had high quality (Newcastle-Ottawa scale score of ≥8). No studies reported on cardiovascular events and mortality rate. Black women had comparable fasting glucose (-0.61 [-1.69 to 2.92] mg/dL; I2=62.5%), yet exhibited increased fasting insulin (6.76 [4.97-8.56] μIU/mL; I2=59.0%); homeostatic model assessment of insulin resistance (1.47 [0.86-2.08]; I2=83.2%); systolic blood pressure (3.32 [0.34-6.30] mm Hg; I2=52.0%); and decreased triglyceride (-32.56 [-54.69 to -10.42] mg/dL; I2=68.0%) compared with White women (all, P≤.03). Groups exhibited comparable total cholesterol, low-density lipoprotein cholesterol, high-density lipoprotein cholesterol, and diastolic blood pressure (all, P≥.06).

CONCLUSIONS

Black women with polycystic ovary syndrome have a greater tendency for an adverse cardiometabolic risk profile (increased insulin, homeostatic model assessment of insulin resistance, and systolic blood pressure) despite lower triglycerides than White women. Our observations support the consideration of these disparities for diagnostic, monitoring, and management practices in Black women and for future guideline recommendations. Given the heterogeneity among studies, future research should address the relative contributions of biologic, environmental, socioeconomic, and healthcare factors to the observed disparities. Furthermore, longitudinal research is required to address patient-pressing complications, including cardiovascular events and mortality rate in Black women with polycystic ovary syndrome as a high-risk yet understudied population.

Association between somatostatin analogues and diabetes mellitus in gastroenteropancreatic neuroendocrine tumor patients: A Surveillance, Epidemiology, and End Results-Medicare analysis of 5235 patients

BACKGROUND

Gastroenteropancreatic neuroendocrine tumors (GEP-NETs) are increasingly common malignancies and tend to have favorable long-term prognoses. Somatostatin analogues (SSA) are a first-line treatment for many NETs. Short-term experiments suggest an association between SSAs and hyperglycemia. However, it is unknown whether there is a relationship between SSAs and clinically significant hyperglycemia causing development of diabetes mellitus (DM), a chronic condition with significant morbidity and mortality.

AIM

In this study, we aimed to compare risk of developing DM in patients treated with SSA vs no SSA treatment.

METHODS AND RESULTS

Using the Surveillance, Epidemiology, and End Results (SEER) database and linked Medicare claims (1991-2016), we identified patients age 65+ with no prior DM diagnosis and a GEP-NET in the stomach, small intestine, appendix, colon, rectum, or pancreas. We used χ² tests to compare SSA-treated and SSA-untreated patients and multivariable Cox regression to assess risk factors for developing DM. Among 8464 GEP-NET patients, 5235 patients had no prior DM and were included for analysis. Of these, 784 (15%) patients received SSAs. In multivariable analysis, the hazard ratio of developing DM with SSA treatment was 1.19, which was not statistically significant (95% CI 0.95-1.49). Significant risk factors for DM included black race, Hispanic ethnicity, prior pancreatic surgery, prior chemotherapy, tumor size >2 cm, pancreas tumors, and higher Charlson scores.

CONCLUSION

DM was very common in GEP-NET patients, affecting 53% of our cohort. Despite prior studies suggesting an association between SSAs and hyperglycemia, our analysis found similar risk of DM in SSA-treated and SSA-untreated GEP-NET patients. Further studies are needed to better understand this relationship. As NET patients have increasingly prolonged survival, it is crucial to identify chronic conditions such as DM that these patients may be at elevated risk for.

Sex Differences in Factors Contributing to the Racial Disparity in Diabetes Risk

INTRODUCTION

Diabetes incidence differs by race in the U.S., with a persistent reported Black-White disparity. However, the factors that contribute to this excess risk in middle-aged and older adults are unclear.

METHODS

This prospective cohort study included 7,171 Black and White adults aged ≥45 years without diabetes at baseline (2003‒2007) who completed a follow-up examination (2013‒2016). Modified Poisson regression was used to obtain sex-stratified RRs for diabetes. Mediation analyses using a change in β coefficient assessed individual and neighborhood factors that contribute to the racial disparity in diabetes incidence. Statistical analyses were conducted in 2018-2019.

RESULTS

The cumulative incidence of diabetes was higher for Black men (16.2%) and women (17.7%) than for White men (11.0%) and women (8.1%). Adjusting for age and prediabetes, diabetes risk was higher for Black women than for White women (RR=1.75, 95% CI=1.47, 2.07) and for Black men than for White men (RR=1.33, 95% CI=1.09, 1.64). The individual factors that attenuated the racial disparity the most were Southern dietary pattern (change in β=42.8%) and neighborhood socioeconomic environment (change in β=26.3%) among men and BMI (change in β=34.4%) and waist circumference (change in β=32.4%) among women. When including all factors collectively, the racial disparity in diabetes incidence was similar for men (RR=1.38, 95% CI=1.04, 1.83) and was attenuated for women (RR=1.41, 95% CI=1.11, 1.81).

CONCLUSIONS

The racial disparity in diabetes incidence remained after accounting for individual and neighborhood factors. Further investigation of additional factors underlying this racial disparity is needed to inform multilevel strategies for diabetes prevention.

Investigating Denominational and Church Attendance Differences in Obesity and Diabetes in Black Christian Men and Women

Prior investigations of the relationships between religious denomination and diabetes and obesity do not consider the nuance within black faith traditions. This study used data from the National Survey of American Life (n = 4344) to identify denominational and religious attendance differences in obesity and diabetes among black Christian men and women. Key findings indicated that black Catholics and Presbyterians had lower odds of diabetes than Baptists. Black men that attended church almost daily were nearly twice as likely to be obese than those that never attend services. These results indicate that denomination and gender should inform faith-based and placed health promotion approaches.

Longitudinal Associations Between Body Mass Index During Young Adulthood, Subsequent Weight Change, and Incident Diabetes During Mid- and Older-Adulthood in Non-Hispanic White and African American Populations: The Atherosclerosis Risk in Communities Study

Background: Excess body mass index (BMI) and weight gain are well-known risk factors for diabetes. Nevertheless, the associations of BMI and weight gain in young adulthood with subsequent diabetes in African Americans, and the standardized effects of these weight variables have not been well studied. Methods: We studied 12,672 white and African American men and women 45-64 years of age (i.e., during mid-adulthood) who participated in the Atherosclerosis Risk in Communities Study visit 1 (1987-1989), and were reexamined at three follow-up examinations. Associations between recalled BMI at age 25 (i.e., during young adulthood) and subsequent weight change with incident diabetes at ages 45 and above (i.e., during mid-adulthood to older adulthood) were examined using Cox proportional hazard models. Results: Over the 9-year follow-up, we identified 1,501 cases of incident diabetes. The incidence rates were higher among African Americans (men: 24.5 and women: 26.3 per 1,000 person-years) compared to whites (men: 16.3 and women: 10.5 per 1,000 person years). Compared to normal-weight individuals at age 25, those who were overweight or obese and those who gained more weight after age 25 had a higher risk of developing diabetes later in all four race-sex groups with the highest risk in African Americans. In the race-sex groups combined, the mutually adjusted hazard ratio for BMI at age 25 and percent weight change were 1.97 (1.79-2.17) and 2.89 (2.59-3.11), respectively, comparing the 85th to the 15th percentiles of the exposures. Conclusions: African Americans were at higher risk of diabetes than whites. Both higher BMI at age 25 and subsequent weight gain were independently associated with higher risk for diabetes in all the race-sex groups; however, overall weight gain was more potent than BMI.

Disparities in insulin resistance between black and white adults in the United States: The role of lifespan stress exposure

BACKGROUND

Disparities in insulin resistance between Black and White adults in the United States are well documented, yet relatively little is known about the psychosocial or biological antecedents of these inequities. The current study examined childhood adversity and contemporaneous psychosocial stressors in adulthood as possible mediators of the racial disparity in insulin resistance. Inflammatory and hypothalamic-pituitary adrenal (HPA) axis mechanisms implicated in associations between lifespan stress exposure and insulin resistance were also considered.

METHODS

Data were derived from the biomarker component of the Midlife in the United States Study (N = 1170, 20% Black, 56% female, Mean age = 54.7 years, SD = 11.6). A homeostatic model assessment of insulin resistance (HOMA-IR) was calculated from fasting glucose and insulin concentrations. Twelve risk factors relating to household dysfunction, socioeconomic disadvantage, and maltreatment were sum scored to index childhood adversity. Measures of adult stress included socioeconomic adversity, major stressful events, everyday discrimination, and lifetime discrimination.

RESULTS

Levels of insulin resistance were higher among Black than White adults. Childhood adversity was positively associated with HOMA-IR, and attenuated 18% of the race difference. Measures of adult stress mediated 33% of the association between childhood adversity and HOMA-IR, and accounted for an additional 47% of the race difference. Higher inflammation and lower nocturnal cortisol both played an important role in mediating the association between stress exposure and HOMA-IR.

CONCLUSIONS

Findings are consistent with prior research showing that childhood adversity and adult stress are salient predictors of glucose metabolism, and extend this work by showing that lifespan stress exposures attenuate a significant portion of the Black-White disparity in HOMA-IR. Results also suggest stress effects on insulin resistance through inflammatory and HPA-axis pathways.

Shared and unique risk factors for depression and diabetes mellitus in a longitudinal study, implications for prevention: an analysis of a longitudinal population sample aged ⩾45 years

OBJECTIVE

The objective of this study was to examine shared and unique risk factors for incident depression and diabetes mellitus in a national longitudinal population-based survey.

METHODS

Canadian National Population Health Survey (NPHS) longitudinal study was used. A subsample of the initial NPHS sample (n = 4845), free of depression or diabetes mellitus at baseline was tracked over a 10-year period. Univariate and multivariate modified Poisson regression models were used to estimate the relative risk (RR). Stratified analyses by sex were conducted to measure its moderating role. The goodness-of-fit of the various models was tested.

RESULTS

The cumulative incidence rate of major depressive disorder and incident diabetes mellitus at 10-year follow-up were 4.1% and 10.1% respectively. Hypertension, daily smoking, physical inactivity and being overweight or obese were shared risk factors for major depressive episode and diabetes mellitus. Being female, family stress, traumatic events, having any chronic disease or heart disease were uniquely associated with depression while increasing age and ethnicity (non-white) were unique risk factors for diabetes mellitus. Also, underweight, family stress, chronic disease, and heart disease were risk factors for major depressive disorder in both sexes. Six risk factors, age, ethnicity (non-white), high blood pressure, daily smoking, physical inactivity, and body mass index were associated with incident diabetes mellitus in both sexes.

CONCLUSION

We found common risk behaviors/conditions not specific to either diabetes mellitus or depression. These risks have also been implicated in the development of a variety of chronic diseases. These findings underline the importance of public health prevention programs targeting generic risk behaviors.

The relationship of family history and risk of type 2 diabetes differs by ancestry

AIM

Type 2 diabetes (T2DM) in a first-degree relative is a risk factor for incident diabetes. Americans of African ancestry (AA) have higher rates of T2DM than Americans of European ancestry (EA). Thus, we aimed to determine whether the presence, number and kinship of affected relatives are associated with race-specific T2DM incidence in a prospective study of participants from the Genetic Study of Atherosclerosis Risk (GeneSTAR), who underwent baseline screening including a detailed family history.

METHODS

Nondiabetic healthy siblings (n=1405) of patients with early-onset coronary artery disease (18-59 years) were enrolled (861 EA and 544 AA) and followed for incident T2DM (mean 14±6 years).

RESULTS

Baseline age was 46.2±7.3 years and 56% were female. T2DM occurred in 12.3% of EA and 19.1% of AA. Among EA, 32.6% had ≥1 affected first-degree relatives versus 53.1% in AA, P<0.0001. In fully adjusted Cox proportional hazard analyses, any family history was related to incident T2DM in EA (HR=2.53, 95% CI: 1.58-4.06) but not in AA (HR=1.01, 0.67-1.53). The number of affected relatives conferred incremental risk of T2DM in EA with HR=1.82 (1.08-3.06), 4.83 (2.15-10.85) and 8.46 (3.09-23.91) for 1, 2, and ≥3 affected, respectively. In AA only ≥3 affected increased risk (HR=2.45, 1.44-4.19). Specific kinship patterns were associated with incident T2DM in EA but not in AA.

CONCLUSIONS

The presence of any first-degree relative with T2DM does not discriminate risk in AA given the high race-specific prevalence of diabetes. Accounting for the number of affected relatives may more appropriately estimate risk for incident diabetes in both races.

Metabolomics Identifies Novel Blood Biomarkers of Pulmonary Function and COPD in the General Population

Determination of metabolomic signatures of pulmonary function and chronic obstructive pulmonary disease (COPD) in the general population could aid in identification and understanding of early disease processes. Metabolome measurements were performed on serum from 4742 individuals (2354 African-Americans and 1529 European-Americans from the Atherosclerosis Risk in Communities study and 859 Europeans from the Cooperative Health Research in the Region of Augsburg study). We examined 368 metabolites in relation to cross-sectional measures of forced expiratory volume in 1 s (FEV1), forced vital capacity (FVC), their ratio (FEV1/FVC) and COPD using multivariable regression followed by meta-analysis. At a false discovery rate of 0.05, 95 metabolites were associated with FEV1 and 100 with FVC (73 overlapping), including inverse associations with branched-chain amino acids and positive associations with glutamine. Ten metabolites were associated with FEV1/FVC and seventeen with COPD (393 cases). Enriched pathways of amino acid metabolism were identified. Associations with FEV1 and FVC were not driven by individuals with COPD. We identified novel metabolic signatures of pulmonary function and COPD in African and European ancestry populations. These may allow development of biomarkers in the general population of early disease pathogenesis, before pulmonary function has decreased to levels diagnostic for COPD.

Influence of obesity, parental history of diabetes, and genes in type 2 diabetes: A case-control study

Obesity, parental history (PH) of type 2 diabetes (T2D), and genes play an important role in T2D development. However, the influence of each factor on T2D variability is unclear. This study aimed to investigate the influence of obesity (body mass index [BMI], waist/hip ratio), PH, and 16 single-nucleotide polymorphisms (SNPs) associated with T2D on T2D variability in Mexico, comparing 1234 non-diabetic controls and 1219 diabetic patients. To replicate the data, a case-control (n = 2904) and a cross-sectional (n = 1901) study were also included. In a multivariate logistic regression model, all factors accounted for only 27.3% of T2D variability: SNPs (8.4%); PH (11.8%) and obesity (7.1%). These factors contributed more in men (33.2%) than in women (25%), specifically when the disease was diagnosed before the age of 46 (46.7% vs. 30%). Genes played a substantially more important role in men than in women (14.9% vs. 5.5%), while obesity and PH played a similar role in both genders. Genes and PH appeared to play a greater role than obesity in T2D. However, obesity contribution was calculated at the time of recruitment and may be underestimated in patients because the BMI decreased linearly with the number of years with the disease. The data suggest that sexual hormones may play important roles in genes that are associated with T2D.

KCNJ11 variants and their effect on the association between serum potassium and diabetes risk in the Atherosclerosis Risk in Communities (ARIC) Study and Jackson Heart Study (JHS) cohorts

BACKGROUND

In the Atherosclerosis Risk in Communities (ARIC) Study and Jackson Heart Study (JHS) cohorts, serum potassium (K) is an independent predictor of diabetes risk, particularly among African-American participants. Experimental studies show that serum K levels affects insulin secretion. The KCNJ11 gene encodes for a K channel that regulates insulin secretion and whose function is affected by serum K levels. Variants in KCNJ11 are associated with increased diabetes risk. We hypothesized that there could be a gene-by-environment interaction between KCNJ11 variation and serum K on diabetes risk.

METHODS

Evaluating a combined cohort of ARIC and JHS participants, we sought to determine if KCNJ11 variants are risk factors for diabetes; and if KCNJ11 variants modify the association between serum K and diabetes risk. Among participants without diabetes at baseline, we performed multivariable logistic regression to determine the effect of serum K, KCNJ11 variants, and their interactions on the odds of incident diabetes mellitus over 8-9 years in the entire cohort and by race.

RESULTS

Of 11,812 participants, 3220 (27%) participants developed diabetes. 48% and 47% had 1 or 2 diabetes risk alleles of rs5215 and rs5219, respectively. Caucasians had higher proportions of these risk alleles compared to African Americans (60% vs 17% for rs5215 and 60% vs 13% for rs5219, p<0.01). Serum K was a significant independent predictor of incident diabetes. Neither rs5215 nor rs5219 was associated with incident diabetes. In multivariable models, we found no statistically significant interactions between race and either rs5215 or rs5219 (P-values 0.493 and 0.496, respectively); nor between serum K and either rs5215 or rs5219 on odds of incident diabetes (P-values 0.534 and 0.687, respectively).

CONCLUSION

In this cohort, rs5215 and rs5219 of KCNJ11 were not significant predictors of incident diabetes nor effect modifiers of the association between serum K and incident diabetes.

Survival-related Selection Bias in Studies of Racial Health Disparities: The Importance of the Target Population and Study Design

The impact of survival-related selection bias has not always been discussed in relevant studies of racial health disparities. Moreover, the analytic approaches most frequently employed in the epidemiologic literature to minimize selection bias are difficult to implement appropriately in racial disparities research. This difficulty stems from the fact that frequently employed analytic techniques require that common causes of survival and the outcome are accurately measured. Unfortunately, such common causes are often unmeasured or poorly measured in racial health disparities studies. In the absence of accurate measures of the aforementioned common causes, redefining the target population or changing the study design represents a useful approach for reducing the extent of survival-related selection bias. To help researchers recognize and minimize survival-related selection bias in racial health disparities studies, we illustrate the aforementioned selection bias and how redefining the target population or changing the study design can be useful.

Association of Modifiable Risk Factors in Young Adulthood With Racial Disparity in Incident Type 2 Diabetes During Middle Adulthood

Importance

In the United States, black individuals are twice as likely to develop type 2 diabetes compared with white individuals, and these disparities are particularly pronounced in young and middle age. Prior studies have identified differences in traditional risk factors that may be associated with racial disparities in diabetes incidence but have not simultaneously adjusted for risk factors measured across multiple domains (eg, the individual and the environment) and updated over time.

Objective

To determine the relative associations of modifiable biological, neighborhood, psychosocial, socioeconomic, and behavioral factors in young adulthood with the observed racial disparity in diabetes incidence between middle-aged black and white individuals.

Design, Setting, and Participants

Black and white men and women from the observational Coronary Artery Risk Development in Young Adults study, aged 18 to 30 years, without diabetes at baseline (1985-1986; N = 4251) were observed through 2015-2016. Sex-stratified multivariable-adjusted Cox proportional hazards modeling, with adjustment for time-updated covariates, was used to estimate risk for incident diabetes. Percent reduction in the β coefficient (the logarithm used to calculate the hazard ratio [HR]) was calculated to compare black to white participants.

Exposures

Self-identified race and factors including biological (eg, fasting glucose, body mass index), neighborhood (racial segregation and tract-level poverty), psychosocial (depressive symptoms), socioeconomic (eg, personal and parental educational attainment, current employment), and behavioral (eg, regular alcohol consumption, smoking) domains.

Main Outcomes and Measures

Incident type 2 diabetes mellitus.

Results

The mean (SD) age at baseline was 25 (3.6) years, 49% (n = 2066) of the sample was black, and 54% (n = 2304) were women. Over a mean follow-up of 24.5 years, 504 cases of incident diabetes were identified. Using sex-stratified multivariable-adjusted Cox proportional hazards models, black women and men were more likely to develop diabetes than white men and women (black women: HR, 2.86 [95% CI, 2.19-3.72] and risk difference [RD], 89 cases/1000 people [95% CI, 61-117]; black men: HR, 1.67 [95% CI, 1.28-2.17] and RD, 47 cases/1000 people [95% CI, 15-78]) after adjustment for age and center. Biological factors were most strongly associated with the disparity in diabetes risk between black and white individuals for women (percent reduction in β, 112%) and men (percent reduction in β, 86%). There was no longer disparity in diabetes risk between black and white middle-aged adults after adjustment for biological, neighborhood, psychosocial, socioeconomic, and behavioral factors measured over time (HR for women, 0.79 [95% CI, 0.55-1.14]; HR for men, 0.92 [95% CI, 0.62-1.38]).

Conclusions and Relevance

In this cohort study comparing black and white participants, there was a statistically significant increased risk of incident type 2 diabetes among black women and men. However, after adjustment for modifiable risk factors during young adulthood, the disparity was no longer statistically significant.

Two Physical Activity Measures: Paffenbarger Physical Activity Questionnaire Versus Aerobics Center Longitudinal Study as Predictors of Adult-Onset Type 2 Diabetes in a Follow-Up Study

PURPOSE

To compare 2 self-report methods of measuring weekly minutes of physical activity based on the Aerobics Center Longitudinal Study (ACLS) questionnaire and question 6 of the Paffenbarger Physical Activity Questionnaire (PPAQ) to determine the better predictor of adult-onset type 2 diabetes mellitus (T2DM).

DESIGN

An observational, prospective study.

SETTING

Survey data from the Adventist Health Study-2 (AHS-2) collected between 2002 and 2006 (baseline) and the Psychosocial Manifestations of Religion Sub-Study (PsyMRS), an AHS-2 subset collected 1 to 4 years later.

PATIENTS

Nine thousand eight hundred seventy-three male and female participants aged 23 to 106 years (mean, 63 years). Three hundred eighty participants reported adult-onset T2DM at follow-up.

MEASURES

Question 6 from the PPAQ and a question adopted from the ACLS were assessed at baseline. Incident diabetes was defined as participants who reported receiving treatment for adult-onset T2DM in the last 12 months in the PsyMRS and not at baseline.

ANALYSIS

Multivariate logistic regression analyses controlled for age, gender, ethnicity, education, body mass index (BMI), diet, and sedentary activity. Each exposure variable was compared to nonexercisers.

RESULTS

The PPAQ (odds ratio [OR]: 0.998; 95% confidence interval [CI]: 0.997-1.000) and the ACLS (OR: 0.999; 95% CI: 0.998-1.001) exhibited similar likelihood of predicting incident adult-onset T2DM in a healthy, mixed-gender population when controlling for several confounders.

CONCLUSIONS

The demonstrative nomenclature of the PPAQ may be more effectual in capturing physically active individuals than the ACLS notwithstanding generalizability and response bias limitations.

Socioeconomic, health, and psychosocial mediators of racial disparities in cognition in early, middle, and late adulthood

Racial disparities in cognitive performance exist across the life course, but it is not known whether mediators of disparities differ by age. Understanding sources of cognitive disparities at different ages can inform policies and interventions. Data were obtained for non-Hispanic Black and White respondents to The National Survey of Midlife Development in the United States from 3 age groups: 28-44 (N = 1210; 20% Black); 45-64 (N = 2693; 15% Black); and 65-85 (N = 1298; 11% Black). Moderated mediation models characterized direct and indirect effects of race on episodic memory and executive function composite scores through economic, health, and psychosocial variables as a function of age group. Education, income, chronic health conditions, and external locus of control mediated cognitive disparities across the life course, although income was a stronger mediator at younger ages. Perceived discrimination was a weaker mediator among young adults due to an absence of racial differences in perceived discrimination in that group. Despite multiple indirect effects, there were still significant unexplained effects of race on cognition that were not moderated by age group. Interventional work is needed to determine whether increasing educational attainment and income, and reducing chronic health conditions and perceived constraints among Blacks, reduce cognitive disparities. Targeting income inequality and discrimination (or buffering the impact of those variables) may be differently effective at reducing cognitive disparities at different stages of the adult life course. (PsycINFO Database Record

Serum potassium is a predictor of incident diabetes in African Americans with normal aldosterone: the Jackson Heart Study

BACKGROUND

Low-normal potassium is a risk factor for diabetes and may account for some of the racial disparity in diabetes risk. Aldosterone affects serum potassium and is associated with insulin resistance.

OBJECTIVES

We sought to confirm the association between potassium and incident diabetes in an African-American cohort, and to determine the effect of aldosterone on this association.

DESIGN

We studied participants from the Jackson Heart Study, an African-American adult cohort, who were without diabetes at baseline. With the use of logistic regression, we characterized the associations of serum, dietary, and urinary potassium with incident diabetes. In addition, we evaluated aldosterone as a potential effect modifier of these associations.

RESULTS

Of 2157 participants, 398 developed diabetes over 8 y. In a minimally adjusted model, serum potassium was a significant predictor of incident diabetes (OR: 0.83; 95% CI: 0.74, 0.92 per SD increment in serum potassium). In multivariable models, we found a significant interaction between serum potassium and aldosterone (P = 0.046). In stratified multivariable models, in those with normal aldosterone (<9 ng/dL, n = 1163), participants in the highest 2 potassium quartiles had significantly lower odds of incident diabetes than did those in the lowest potassium quartile [OR (95% CI): 0.61 (0.39, 0.97) and 0.54 (0.33, 0.90), respectively]. Among those with high-normal aldosterone (≥9 ng/dL, n = 202), we found no significant association between serum potassium and incident diabetes. In these stratified models, serum aldosterone was not a significant predictor of incident diabetes. We found no statistically significant associations between dietary or urinary potassium and incident diabetes.

CONCLUSIONS

In this African-American cohort, we found that aldosterone may modify the association between serum potassium and incident diabetes. In participants with normal aldosterone, high-normal serum potassium was associated with a lower risk of diabetes than was low-normal serum potassium. Additional studies are warranted to determine whether serum potassium is a modifiable risk factor that could be a target for diabetes prevention. This trial was registered at clinicaltrials.gov as NCT00415415.

Age-Related Differences in Health-Related Quality of Life in COPD: An Analysis of the COPDGene and SPIROMICS Cohorts

OBJECTIVE

Younger persons with COPD report worse health-related quality of life (HRQL) than do older individuals. The factors explaining these differences remain unclear. The objective of this article was to explore factors associated with age-related differences in HRQL in COPD.

METHODS

Cross-sectional analysis of participants with COPD, any Global Initiative for Chronic Obstructive Lung Disease grade of airflow limitation, and ≥ 50 years old in two cohorts: the Genetic Epidemiology of COPD (COPDGene) study and the Subpopulations and Intermediate Outcome Measures in COPD Study (SPIROMICS). We compared St. George's Respiratory Questionnaire (SGRQ) scores by age group: middle-aged (age, 50-64) vs older (age, 65-80) adults. We used multivariate linear modeling to test associations of age with HRQL, adjusting for demographic and clinical characteristics and comorbidities.

RESULTS

Among 4,097 participants in the COPDGene study (2,170 middle-aged and 1,927 older adults) SGRQ total scores were higher (worse) among middle-aged (mean difference, -4.2 points; 95% CI, -5.7 to -2.6; P < .001) than older adults. Age had a statistically significant interaction with dyspnea (P < .001). Greater dyspnea severity (modified Medical Research Council ≥ 2, compared with 0-1) had a stronger association with SGRQ score among middle-aged (β, 24.6; 95% CI, 23.2-25.9) than older-adult (β, 21.0; 95% CI, 19.6-22.3) participants. In analyses using SGRQ as outcome in 1,522 participants in SPIROMICS (598 middle-aged and 924 older adults), we found similar associations, confirming that for the same severity of dyspnea there is a stronger association with HRQL among younger individuals.

CONCLUSIONS

Age-related differences in HRQL may be explained by a higher impact of dyspnea among younger subjects with COPD.

TRIAL REGISTRY

ClinicalTrials.gov; No.: NCT00608764 and No.: NCT01969344; URL: www.clinicaltrials.gov.

Racial-ethnic disparities in the association between risk factors and diabetes: The Northern Manhattan Study

PURPOSE

To identify risk factors (RF) for diabetes within a multiethnic cohort and to examine whether race-ethnicity modified their effects.

METHODS

Participants in the Northern Manhattan Study without diabetes at baseline were studied from 1993 to 2014 (n=2430). Weibull regression models with interval censoring data were fit to calculate hazard ratios and 95% confidence intervals for incident diabetes. We tested for interactions between RF and race-ethnicity.

RESULTS

During a mean follow-up period of 11years, there were 449 diagnoses of diabetes. Being non-Hispanic black (HR 1.69 95% CI 1.11-2.59) or Hispanic (HR 2.25 95% CI 1.48-3.40) versus non-Hispanic white, and body mass index (BMI; HR 1.34 per SD 95% CI 1.21-1.49) were associated with greater risk of diabetes; high-density lipoprotein cholesterol (HR 0.75 95% CI 0.66-0.86) was protective. There were interactions by race-ethnicity. In stratified models, the effects of BMI, current smoking, and C-reactive protein (CRP) on risk of diabetes differed by race-ethnicity (p for interaction <0.05). The effects were greater among non-Hispanic whites than non-Hispanic blacks and Hispanics.

CONCLUSIONS

Although Hispanics and non-Hispanic blacks had a greater risk of diabetes than whites, there were variations by race-ethnicity in the association of BMI, smoking, and CRP with risk of diabetes. Unique approaches should be considered to reduce diabetes as traditional RF may not be as influential in minority populations.

Novel Risk Factors for Type 2 Diabetes in African-Americans

In the USA, compared to whites, African-Americans are disproportionately impacted by the diabetes epidemic. Traditional diabetes risk factors, such as obesity, are more common among African-Americans, but these traditional risk factors do not explain all of the disparity in diabetes risk. Recent research has identified novel environmental, lifestyle, physiologic, and genetic risk factors for diabetes, some of which appear to impact African-Americans more than whites. This manuscript reviews the recent literature to highlight some of these novel risk factors that may be contributing to the racial disparity in diabetes risk. Further study is needed of the modifiable risk factors for development of interventions to reduce the risk of diabetes in African-Americans, as well as other high-risk populations.

Quantifying the Incremental and Aggregate Cost of Missed Workdays in Adults with Diabetes

OBJECTIVE

Although the national cost of missed workdays associated with diabetes has been estimated previously, we use the most recent available national data and methodology to update the individual and national estimates for the U.S population.

METHODS

We identified 14,429 employed individuals ≥ 18 years of age in 2011 Medical Expenditure Panel Survey (MEPS) data. Diabetes and missed workdays were based on self-report, and cost was based on multiplying the daily wage rate for each individual by the number of missed days. Adjusted total national burden of missed workdays associated with diabetes was calculated using a novel two-part model to simultaneously estimate the association of diabetes with the number and cost of missed workdays.

RESULTS

The unadjusted annual mean 2011 cost of missed workdays was $277 (95 % CI 177.0-378.0) for individuals with diabetes relative to $160 (95 % CI $130-$189) for those without. The incremental cost of missed workdays associated with diabetes was $120 (95 % CI $30.7-$209.1). Based on the US population in 2011, the unadjusted national burden of missed workdays associated with diabetes was estimated to be $2.7 billion, while the fully adjusted incremental national burden was estimated to be $1.1 billion.

CONCLUSIONS

We provide more precise estimates of the cost burden of diabetes due to missed workdays on the U.S population. The high incremental and total cost burden of missed workdays among Americans with diabetes suggests the need for interventions to improve diabetes care management among employed individuals.

Socioeconomic Characteristics Are Major Contributors to Ethnic Differences in Health Status in Obstructive Lung Disease: An Analysis of the National Health and Nutrition Examination Survey 2007-2010

BACKGROUND

Understanding ethnic differences in health status (HS) could help in designing culturally appropriate interventions. We hypothesized that racial and ethnic differences exist in HS between non-Hispanic whites and Mexican Americans with obstructive lung disease (OLD) and that these differences are mediated by socioeconomic factors.

METHODS

We analyzed 826 US adults aged ≥ 30 years self-identified as Mexican American or non-Hispanic white with spirometry-confirmed OLD (FEV₁/FVC < 0.7) who participated in the National Health and Nutrition Examination Survey 2007-2010. We assessed associations between Mexican American ethnicity and self-reported HS using logistic regression models adjusted for demographics, smoking status, number of comorbidities, limitations for work, and lung function and tested the contribution of education and health-care access to ethnic differences in HS.

RESULTS

Among Mexican Americans with OLD, worse (fair or poor) HS was more prevalent than among non-Hispanic whites (weighted percentage [SE], 46.6% [5.0] vs 15.2% [1.6]; P < .001). In bivariate analysis, socioeconomic characteristics were associated with lower odds of reporting poor HS (high school graduation: OR, 0.24 [95% CI, 0.10-0.40]; access to health care: OR, 0.50 [95% CI, 0.30-0.80]). In fully adjusted models, a strong association was found between Mexican American ethnicity (vs non-Hispanic white) and fair or poor HS (OR, 7.52; 95% CI, 4.43-12.78; P < .001). Higher education and access to health care contributed to lowering the Mexican American ethnicity odds of fair or poor HS by 47% and 16%, respectively, and together, they contributed 55% to reducing the differences in HS with non-Hispanic whites.

CONCLUSIONS

Mexican Americans with OLD report poorer overall HS than non-Hispanic whites, and education and access to health care are large contributors to the difference.

Evidence Gap on the Prevalence of Non-conventional Risk Factors for Type 2 Diabetes in Iran

OBJECTIVES

Robust scientific evidence exists about the role of non-conventional risk factors in type 2 diabetes worldwide. The current epidemiological pattern of the disease in Iran suggests a precipitating role for these non-conventional risk factors. This review was performed to examine the research evidence suggesting a higher prevalence of non-conventional type 2 diabetes risk factors in Iran.

METHODS

MeSH keywords were applied to search several databases, including PUBMED, MEDLINE, AMED, EMBASE, Iran DOC, and the Scientific Information Database without a time limit from inception to September 2011. The quality of the non-interventional and population-based studies on Iranians included in these databases was assessed by the authors and any disagreement was resolved with consensus.

RESULTS

The literature search yielded 1847 publications, of which 62 were included in this study after eliminating non-relevant and overlapping papers. No study was found that verified a higher prevalence of the non-conventional type 2 diabetes risk factors in the Iranian population.

CONCLUSION

The identified evidence gap about the role of prominent non-conventional risk factors of type 2 diabetes in the Iranian population could be a major caveat in the application of an evidence-based approach to endorse or reject existing hypothesis about these risk factors. Studies on the prevalence of non-conventional biomarkers of type 2 diabetes among Iranians could be a promising area of research.