A Large-Scale Genome-Wide Study of Gene-Sleep Duration Interactions for Blood Pressure in 811,405 Individuals from Diverse Populations

Although both short and long sleep duration are associated with elevated hypertension risk, our understanding of their interplay with biological pathways governing blood pressure remains limited. To address this, we carried out genome-wide cross-population gene-by-short-sleep and long-sleep duration interaction analyses for three blood pressure traits (systolic, diastolic, and pulse pressure) in 811,405 individuals from diverse population groups. We discover 22 novel gene-sleep duration interaction loci for blood pressure, mapped to genes involved in neurological, thyroidal, bone metabolism, and hematopoietic pathways. Non-overlap between short sleep (12) and long sleep (10) interactions underscores the plausibility of distinct influences of both sleep duration extremes in cardiovascular health. With several of our loci reflecting specificity towards population background or sex, our discovery sheds light on the importance of embracing granularity when addressing heterogeneity entangled in gene-environment interactions, and in therapeutic design approaches for blood pressure management.

Association of Visceral Adipose Tissue and Insulin Resistance with Incident Metabolic Syndrome Independent of Obesity Status: The IRAS Family Study

OBJECTIVE

Although increasing evidence suggests that visceral adipose tissue (VAT) is a major underlying cause of metabolic syndrome (MetS), few studies have measured VAT at multiple time points in diverse populations. VAT and insulin resistance were hypothesized to differ by MetS status within BMI category in the Insulin Resistance Atherosclerosis Study (IRAS) Family Study and, further, that baseline VAT and insulin resistance and increases over time are associated with incident MetS.

METHODS

Generalized estimating equations were used for differences in body fat distribution and insulin resistance by MetS status. Mixed effects logistic regression was used for the association of baseline and change in adiposity and insulin resistance with incident MetS across 5 years, adjusted for age, sex, race/ethnicity, and family correlation.

RESULTS

VAT and insulin sensitivity differed significantly by MetS status and BMI category at baseline. VAT and homeostatic model assessment of insulin resistance (HOMA-IR) at baseline (VAT odds ratio [OR] = 1.16 [95% CI: 1.12-2.31]; HOMA-IR OR = 1.85 [95% CI: 1.32-2.58]) and increases over time (VAT OR = 1.55 [95% CI: 1.22-1.98]; HOMA-IR OR = 3.23 [95% CI: 2.20-4.73]) were associated with incident MetS independent of BMI category.

CONCLUSIONS

Differing levels of VAT may be driving metabolic heterogeneity within BMI categories. Both overall and abdominal obesity (VAT) may play a role in the development of MetS. Increased VAT over time contributed additional risk.

Body fat distribution, menopausal hormone therapy and incident type 2 diabetes in postmenopausal women of the MESA study

OBJECTIVES

We investigated the association between menopausal hormone therapy (MHT) and incident type 2 diabetes in postmenopausal women, and explored the potential modifying role of body fat distribution on this association.

METHODS

We included 2210 postmenopausal women without prevalent diabetes at recruitment (2000-2002) from the Multiethnic Study of Atherosclerosis. Cox proportional hazards models were used to examine associations of MHT and MHT types with incident diabetes, testing for variation according to body fat distribution.

RESULTS

Over a median follow-up of 11.1 years, there were 226 incident cases of diabetes. There were no significant interactions with central or generalized body fatness. In fully adjusted models, current and past MHT use was associated with a greater risk of incident diabetes [HR: 1.66 (1.18-2.35) and 1.60 (1.11-2.30) respectively]. Estrogen only (ET) and combined progestin and estrogen (PET) formulations were similarly associated with a greater risk of incident diabetes [HR: 1.52 (1.03-2.24) and 1.77 (1.15-2.72) respectively].

CONCLUSIONS

In our observational study of middle-aged and older, non-diabetic postmenopausal women, a current or past use of MHT was independently associated with a greater risk of incident diabetes. ET and PET are associated with similar risks of incident diabetes in postmenopausal women. The association of MHT use with incident diabetes is the same irrespective of body mass index (BMI) or waist circumference.

Translational Research Training at Various Levels of Professional Experience to Address Health Disparities

Translational research addressing health disparities brings interventions and medical discoveries into clinical practice to improve health outcomes. However, academic researchers' and clinicians' lack of understanding of methodologies limits the application of basic science to clinical settings. To solve the problem, a multidisciplinary collaboration from two academic institutions offered a workshop building on translational research methodologies to clarify the measures and interventions needed to address health disparities from a research perspective. Three two-day workshops targeted underrepresented minority participants whose research experience and professional development varied. The evaluation surveys administered after the three workshops indicated that workshop 1 which focused on translational and educational research increased participants' knowledge, and made all participants think critically about the subject. Training opportunities focused on translational research can enhance researchers and clinicians' confidence and capabilities to address health disparities.

Effect of protein source during weight loss on body composition, cardiometabolic risk and physical performance in abdominally obese, older adults: a pilot feeding study

OBJECTIVES

The purpose of this pilot study was to begin to examine the effect of dietary protein source (soy protein versus non-soy protein) during weight loss on body composition, and cardiometabolic and functional decline risk factors in older, abdominally obese adults.

DESIGN

Two-arm, single-blind, randomized, controlled trial.

SETTING

Wake Forest School of Medicine, Winston-Salem NC 27157, USA.

PARTICIPANTS

25 older (68.4±5.5 years, 88% female), abdominally obese (BMI: 35.1±4.3 kg/m2; WC: 101.4±13.1 cm) men and women were randomized to participate in the study.

INTERVENTION

A 12-week weight loss intervention, with participants randomized to consume soy protein-based meal replacements (S; n=12) or non-soy protein-based meal replacements (NS; n=12), in addition to prepared meals, and all participants targeted to receive an individualized caloric deficit of 500 kcal/day.

MEASUREMENTS

Body weight and composition (assessed via DXA and CT), conventional biomarkers of cardiometabolic risk, and physical performance measures were assessed pre- and post-intervention. Additional endpoints of feasibility (accrual, participation, retention, compliance, and safety) are reported.

RESULTS

A total of 24 participants (87% female) completed the study (96% retention) and lost an average of 7.8±3.0 kg over the 12-week period, with no difference seen between groups (p=0.83). Although nearly all measures of global and regional body composition were significantly reduced following the 12-week intervention, differences were not observed between groups. Among cardiometabolic risk factors and physical performance measures, only diastolic blood pressure was significantly lower in the NS group compared to the S group (66.7±2.7 mmHg vs 73.5±2.7 mmHg, respectively; p=0.04). Interestingly, in groups combined, despite significant reductions in body weight and lean mass, no significant changes in 400-meter walk time (+5.3±43.4 s), short physical performance battery score (+0.1±1.0), grip strength (-0.3±3.2 kg), or relative knee extensor strength (-0.0±0.0 N/m/cm3 thigh muscle volume) were observed.

CONCLUSIONS

Data presented here suggest that a 12-week weight loss intervention, which incorporates S and NS meal replacement products, is associated with clinically significant weight loss and improvements in several parameters of cardiometabolic risk and unchanged physical function and strength. RESULTS do not differ by protein source and suggest that soy protein is at least as good as other protein sources for weight loss during low-calorie dietary interventions in older adults.

A metabolically healthy obese phenotype in hispanic participants in the IRAS family study

OBJECTIVE

Some obese individuals appear to be protected from developing type 2 diabetes mellitus and cardiovascular disease (CVD). This has led to characterizing body size phenotypes based on cardiometabolic risk factors specifically as obese or overweight, and as metabolically healthy (MH) or metabolically abnormal (MA) based upon blood pressure, lipids, glucose homeostasis, and inflammatory parameters. The aim of this study was to measure the prevalence of and describe fat distribution across these phenotypes in a minority population.

DESIGN AND METHODS

Hispanic participants (N = 1054) in the IRAS Family Study were categorized into different body size phenotypes. Computed tomography (CT) abdominal scans were evaluated for measures of nonalcoholic fatty liver disease (NAFLD) and abdominal fat distribution. Statistical models adjusting for familial relationships were estimated.

RESULTS

Seventy percent (70%) of the Hispanic cohort was overweight (32%) or obese (38%). Forty-one percent (n = 138) of overweight participants and 19% (n = 74) of obese participants met criteria for MH. Adjusted analyses showed the MH phenotype was associated with lower visceral adipose tissue (VAT) and higher liver density (indicating lower fat content) in obese participants (p = 0.0005 and p = 0.0002, respectively), and lower VAT but not liver density in overweight participants (p = 0.008 and p = 0.162, respectively) compared to their MA counterparts. Odds of NAFLD were reduced in MH obese (OR = 0.34, p = 0.0007) compared to MA obese. VAT did not differ between MH obese or overweight and normal weight groups.

CONCLUSIONS

These findings suggest that lower levels of visceral and liver fat, despite overall increased total body fat, may be a defining feature of MH obesity in Hispanic Americans.

Sleep duration, insomnia, and coronary heart disease among postmenopausal women in the Women's Health Initiative

BACKGROUND

Long and short sleep duration are associated with increased risk for coronary heart disease (CHD) and cardiovascular disease (CVD); however, evidence is inconsistent. We sought to identify whether self-reported sleep duration and insomnia, based on a validated questionnaire, are associated with increased incident CHD and CVD among postmenopausal women.

METHODS

Women's Health Initiative Observational Study Participants (N=86,329; 50-79 years) who reported on sleep at baseline were followed for incident CVD events. Associations of sleep duration and insomnia with incident CHD and CVD were evaluated using Cox proportional hazards models over 10.3 years.

RESULTS

Women with high insomnia scores had elevated risk of CHD (38%) and CVD (27%) after adjustment for age and race, and in fully adjusted models (hazard ratio [HR]=1.19, 95% confidence interval [CI] 1.09-1.30; 1.11 95% CI 1.03-2.00). Shorter (≤5 hours) and longer (≥10 hours) sleep duration demonstrated significantly higher incident CHD (25%) and CVD (19%) in age- and race-adjusted models, but this was not significant in fully adjusted models. Formal tests for interaction indicated significant interactions between sleep duration and insomnia for risk of CHD (p<0.01) and CVD (p=0.02). Women with high insomnia scores and long sleep demonstrated the greatest risk of incident CHD compared to midrange sleep duration (HR=1.93, 95% CI 1.06-3.51) in fully adjusted models.

CONCLUSIONS

Sleep duration and insomnia are associated with CHD and CVD risk, and may interact to cause almost double the risk of CHD and CVD. Additional research is needed to understand how sleep quality modifies the association between prolonged sleep and cardiovascular outcomes.

Mentoring programs for underrepresented minority faculty in academic medical centers: a systematic review of the literature

PURPOSE

Mentoring is critical for career advancement in academic medicine. However, underrepresented minority (URM) faculty often receive less mentoring than their nonminority peers. The authors conducted a comprehensive review of published mentoring programs designed for URM faculty to identify "promising practices."

METHOD

Databases (PubMed, PsycINFO, ERIC, PsychLit, Google Scholar, Dissertations Abstracts International, CINHAL, Sociological Abstracts) were searched for articles describing URM faculty mentoring programs. The RE-AIM framework (Reach, Effectiveness, Adoption, Implementation, and Maintenance) formed the model for analyzing programs.

RESULTS

The search identified 73 citations. Abstract reviews led to retrieval of 38 full-text articles for assessment; 18 articles describing 13 programs were selected for review. The reach of these programs ranged from 7 to 128 participants. Most evaluated programs on the basis of the number of grant applications and manuscripts produced or satisfaction with program content. Programs offered a variety of training experiences, and adoption was relatively high, with minor changes made for implementing the intended content. Barriers included time-restricted funding, inadequate evaluation due to few participants, significant time commitments required from mentors, and difficulty in addressing institutional challenges faced by URM faculty. Program sustainability was a concern because programs were supported through external funds, with minimal institutional support.

CONCLUSIONS

Mentoring is an important part of academic medicine, particularly for URM faculty who often experience unique career challenges. Despite this need, relatively few publications exist to document mentoring programs for this population. Institutionally supported mentoring programs for URM faculty are needed, along with detailed plans for program sustainability.

Comparison of BMI and physical activity between old order Amish children and non-Amish children

OBJECTIVE

The Old Order Amish (OOA) is a conservative Christian sect of European origin living in Pennsylvania. Diabetes is rare in adult OOA despite a mean BMI rivaling that in the general U.S. non-Hispanic white population. The current study examines childhood factors that may contribute to the low prevalence of diabetes in the OOA by comparing OOA children aged 8-19 years with National Health and Nutrition Examination Survey (NHANES) data and children from Maryland's Eastern Shore (ES), a nearby, non-Amish, rural community. We hypothesized that pediatric overweight is less common in OOA children, that physical activity (PA) and BMI are inversely correlated, and that OOA children are more physically active than ES children.

RESEARCH DESIGN AND METHODS

We obtained anthropometric data in 270 OOA children and 229 ES children (166 non-Hispanic white, 60 non-Hispanic black, 3 Hispanic). PA was measured by hip-worn accelerometers in all ES children and in 198 OOA children. Instrumentation in 43 OOA children was identical to ES children.

RESULTS

OOA children were approximately 3.3 times less likely than non-Hispanic white ES children and NHANES estimates to be overweight (BMI ≥85th percentile, Centers for Disease Control and Prevention). Time spent in moderate/vigorous PA (MVPA) was inversely correlated to BMI z-score (r = -0.24, P = 0.0006). PA levels did not differ by ethnicity within the ES group, but OOA children spent an additional 34 min/day in light activity (442 ± 56 vs. 408 ± 75, P = 0.005) and, impressively, an additional 53 min/day in MVPA (106 ± 54 vs. 53 ± 32, P < 0.0001) compared with ES children. In both groups, boys were more active than girls but OOA girls were easily more active than ES boys.

CONCLUSIONS

We confirmed all three hypotheses. Together with our previous data, the study implies that the OOA tend to gain their excess weight relatively late in life and that OOA children are very physically active, both of which may provide some long-term protection against diabetes.

Self-reported snoring and risk of cardiovascular disease among postmenopausal women (from the Women's Health Initiative)

Habitual snoring may be associated with cardiovascular disease (CVD); however, limited evidence exists among women. We investigated whether frequent snoring is a predictor of coronary heart disease (CHD) and stroke among 42,244 postmenopausal women participating in the Women's Health Initiative Observational Study. Participants provided self-reported information regarding snoring habits at baseline (1993 to 1998) and were followed up for outcomes through August 2009. Physician adjudicators confirmed CHD (defined as myocardial infarction, CHD death, revascularization procedures, or hospitalized angina) and ischemic stroke. Cox proportional hazards models were used to evaluate whether snoring frequency is a significant predictor of the adjudicated outcomes. We observed 2,401 incident cases of CHD during 437,899 person-years of follow-up. After adjusting for age and race, frequent snoring was associated with incident CHD (hazard ratio [HR] 1.54, 95% confidence interval [CI] 1.39 to 1.70) and stroke (HR 1.41, 95% CI 1.19 to 1.66), and all CVD (HR 1.46, 95% CI 1.34 to 1.60). In fully adjusted models that included CVD risk factors such as obesity, hypertension, and diabetes, frequent snoring was associated with a more modest increase in incident CHD (HR 1.14, 95% CI 1.01 to 1.28), stroke (HR 1.19, 95% CI 1.02 to 1.40), and CVD (HR 1.12, 95% CI 1.01 to 1.24). In conclusion, snoring is associated with a modest increased risk of incident CHD, stroke, and CVD after adjustment for CVD risk factors. Additional studies are needed to elucidate the mechanisms by which snoring might be associated with CVD risk factors and outcomes.

Lifestyle factors and 5-year abdominal fat accumulation in a minority cohort: the IRAS Family Study

The objective of this study was to examine whether lifestyle factors were associated with 5-year change in abdominal fat measured by computed tomography (CT) in the Insulin Resistance and Atherosclerosis (IRAS) Family Study. We obtained abdominal CT scans at baseline and at 5 years, from African Americans (AA) (N = 339) and Hispanic Americans (N = 775), aged 18-81 years. Visceral (VAT) and subcutaneous (SAT) adipose tissue was measured at the L4/L5 vertebral level. Physical activity was documented by self-report of vigorous activity and a 1-year recall instrument. Dietary intake was assessed at follow-up using a semi-quantitative food frequency questionnaire referencing the previous year. Generalized linear models, accounting for family structure, were used to assess the associations between percent change in fat accumulation and smoking, physical activity, total calories, polyunsaturated, monounsaturated, protein, and saturated fat intake, percent of calories from sweets, and soluble and insoluble fiber. Soluble fiber intake and participation in vigorous activity were inversely related to change in VAT, independent of change in BMI. For each 10 g increase in soluble fiber, rate of VAT accumulation decreased by 3.7% (P = 0.01). Soluble fiber was not associated with change in SAT (0.2%, P = 0.82). Moderately active participants had a 7.4% decrease in rate of VAT accumulation and a 3.6% decrease in rate of SAT accumulation versus less active participants (P = 0.003 and P = 0.01, respectively). Total energy expenditure was also inversely associated with accumulation of VAT. Soluble fiber intake and increased physical activity were related to decreased VAT accumulation over 5 years.

Diabetes and adverse mental health among African Americans

This article reviews the connection between diabetes and adverse mental health among African Americans. Concern about safe insulin prescribing and administration is raised, and the importance of integrated physical and mental health care in the prevention and control of diabetes is highlighted.

From politics to parity: using a health disparities index to guide legislative efforts for health equity

OBJECTIVES

We created an index quantifying the longitudinal burden of racial health disparities by state and compared this index to variables to guide the construction of, and validate support for, legislative efforts aimed at eliminating health disparities.

METHODS

We evaluated 5 focus areas of greatest racial disparities in health from 1999 to 2005 and compiled state health disparities index (HDI) scores. We compared these scores with variables representing the purported social determinants of health.

RESULTS

Massachusetts (0.35), Oklahoma (0.35), and Washington (0.39) averaged the fewest disparities. Michigan (1.22), Wisconsin (1.32), and Illinois (1.50) averaged the greatest disparities. The statistical reference point for nationwide average racial disparities was 1.00. The longitudinal mixed model procedure yielded statistically significant correlations between HDI scores and Black state population percentage as well as with the racial gap in uninsured percentages. We noted a trend for HDI correlations with median household income ratios.

CONCLUSIONS

On the basis of the HDI-established trends in the extent and distribution of racial health disparities, and their correlated social determinants of health, policymakers should consider incorporating this tool to advise future efforts in minority health legislation.

Intensive lifestyle intervention improves physical function among obese adults with knee pain: findings from the Look AHEAD trial

Lifestyle interventions have resulted in weight loss or improved physical fitness among individuals with obesity, which may lead to improved physical function. This prospective investigation involved participants in the Action for Health in Diabetes (Look AHEAD) trial who reported knee pain at baseline (n = 2,203). The purposes of this investigation were to determine whether an Intensive Lifestyle Intervention (ILI) condition resulted in improvement in self-reported physical function from baseline to 12 months vs. a Diabetes Support and Education (DSE) condition, and whether changes in weight or fitness mediated the effect of the ILI. Outcome measures included the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) pain, stiffness, and physical function subscales, and WOMAC summary score. ILI participants exhibited greater adjusted mean weight loss (s.e.) vs. DSE participants (-9.02 kg (0.48) vs. -0.78 kg (0.49); P < 0.001)). ILI participants also demonstrated more favorable change in WOMAC summary scores vs. DSE participants (β (s.e.) = -1.81 (0.63); P = 0.004). Multiple regression mediation analyses revealed that weight loss was a mediator of the effect of the ILI intervention on change in WOMAC pain, function, and summary scores (P < 0.001). In separate analyses, increased fitness also mediated the effect of the ILI intervention upon WOMAC summary score (P < 0.001). The ILI condition resulted in significant improvement in physical function among overweight and obese adults with diabetes and knee pain. The ILI condition also resulted in significant weight loss and improved fitness, which are possible mechanisms through which the ILI condition improved physical function.

Impact of abdominal visceral and subcutaneous adipose tissue on cardiometabolic risk factors: the Jackson Heart Study

OBJECTIVE

Obesity is a major driver of cardiometabolic risk. Abdominal visceral adipose tissue (VAT) and sc adipose tissue (SAT) may confer differential metabolic risk profiles. We investigated the relations of VAT and SAT with cardiometabolic risk factors in the Jackson Heart Study cohort.

METHODS

Participants from the Jackson Heart Study (n=2477; 64% women; mean age, 58 yr) underwent multidetector computed tomography, and the volumetric amounts of VAT and SAT were assessed between 2007 and 2009. Cardiometabolic risk factors were examined by sex in relation to VAT and SAT.

RESULTS

Men had a higher mean volume of VAT (873 vs. 793 cm3) and a lower mean volume of SAT (1730 vs. 2659 cm3) than women (P=0.0001). Per 1-sd increment in either VAT or SAT, we observed elevated levels of fasting plasma glucose and triglyceride, lower levels of high-density lipoprotein-cholesterol, and increased odds ratios for hypertension, diabetes, and metabolic syndrome. The effect size of VAT in women was larger than that of SAT [fasting plasma glucose, 5.51±1.0 vs. 3.36±0.9; triglyceride, 0.17±0.01 vs. 0.05±0.01; high-density lipoprotein-cholesterol, -5.36±0.4 vs. -2.85±0.4; and odds ratio for hypertension, 1.62 (1.4-1.9) vs. 1.40 (1.2-1.6); diabetes, 1.82 (1.6-2.1) vs. 1.58 (1.4-1.8); and metabolic syndrome, 3.34 (2.8-4.0) vs. 2.06 (1.8-2.4), respectively; P<0.0001 for difference between VAT and SAT]. Similar patterns were also observed in men. Furthermore, VAT remained associated with most risk factors even after accounting for body mass index (P ranging from 0.006-0.0001). The relationship of VAT to most risk factors was significantly different between women and men.

CONCLUSIONS

Abdominal VAT and SAT are both associated with adverse cardiometabolic risk factors, but VAT remains more strongly associated with these risk factors. The results from this study suggest that relations with cardiometabolic risk factors are consistent with a pathogenic role of abdominal adiposity in participants of African ancestry.

Sleep duration and five-year abdominal fat accumulation in a minority cohort: the IRAS family study

STUDY OBJECTIVES

To study 5-year change in computed tomography (CT)-derived visceral adipose tissue (VAT) and subcutaneous adipose tissue (SAT) associated with sleep duration in 2 minority groups.

DESIGN

Longitudinal epidemiologic study.

SETTING

Three US communities.

PARTICIPANTS

African Americans (N = 332) and Hispanic Americans (N = 775), aged 18-81 years, participating in the IRAS Family Study.

INTERVENTIONS

none

MEASUREMENTS AND RESULTS

Abdominal CT scans and BMI obtained at a 5-year interval. Sleep duration was assessed by questionnaire at baseline and categorized as < or = 5 h, 6-7 h, and > or = 8 h. Generalized estimating equations assessed the association between sleep duration and 5-year fat accumulation with adjustment for age, race, gender, study site, baseline fat measure, physical activity, total calories, smoking status, and education. Age interacted with sleep duration to predict change in fat measures (P < 0.01). In those younger than 40 years, < or = 5 h of sleep was related to a greater accumulation of BMI (1.8 kg/m2, P < 0.001), SAT (42 cm2, P < 0.0001), and VAT (13 cm2, P > 0.01), compared to sleep duration between 6 and 7 h. Eight hours or more of sleep was also significantly related to a greater accumulation of BMI (0.8 kg/m2, P < 0.001), SAT (20 cm2, P < 0.01) and VAT (6 cm2, P < 0.05) compared to sleep duration between 6 and 7 h. No significant relationship existed between sleep duration and fat depot change in participants older than 40 years old.

CONCLUSIONS

In this minority cohort, extremes of sleep duration are related to increases in BMI, SAT, and VAT in persons younger than 40 years old.

Vitamin d, adiposity, and calcified atherosclerotic plaque in african-americans

CONTEXT

Inverse associations are reported between circulating 25-hydroxyvitamin D and visceral adiposity. The effects of vitamin D levels on atherosclerosis are unknown.

OBJECTIVE

The objective of this study was to test for relationships between vitamin D, adiposity, bone density, and atherosclerosis in African-Americans.

DESIGN

Circulating 25-hydroxyvitamin D, 1,25 dihydroxyvitamin D, intact PTH, C-reactive protein and computed tomography-derived calcified atherosclerotic plaque (CP), bone density, and fat volumes were measured.

SETTING

Examinations were performed at a single outpatient general clinical research center visit.

SUBJECTS

Three hundred forty African-Americans with type 2 diabetes were evaluated. Mean +/- SD age was 55.6 +/- 9.6 yr, diabetes duration 10.6 +/- 8.3 yr, glomerular filtration rate 1.6 +/- 0.5 ml/sec, body mass index 35.6 +/- 8.7 kg/m(2), and 25-hydroxyvitamin D concentration 50.4 +/- 30.5 nmol/liter.

MAIN OUTCOME MEASURE

Biomarkers were tested for association with pericardial, visceral, im, and sc adipose tissues; thoracic and lumbar vertebral bone density; and aorta, coronary, and carotid artery CP.

RESULTS

Adjusting for age, gender, body mass index, glycosylated hemoglobin, and glomerular filtration rate, 25-hydroxyvitamin D was negatively associated with visceral adiposity (P = 0.009) and positively associated with carotid artery CP and aorta CP (P = 0.013 and 0.014, respectively) but not with coronary artery CP or bone density.

CONCLUSIONS

We confirmed an inverse association between vitamin D and visceral adiposity in African-Americans with diabetes. In addition, positive associations exist between 25-hydroxyvitamin D and aorta and carotid artery CP in African-Americans. The effects of supplementing vitamin D to raise the serum 25-hydroxyvitamin D level on atherosclerosis in African-Americans are unknown. Prospective trials are needed to determine the cardiovascular effects of supplemental vitamin D in this ethnic group.

Association of plasma vitamin D levels with adiposity in Hispanic and African Americans

CONTEXT

Previous studies have suggested vitamin D insufficiency is associated with increased obesity; however, the relationship between 25-hydroxyvitamin D (25[OH]D) and 1,25-dihydroxyvitamin D (1,25[OH](2)D) and measures of adiposity has not been well characterized in minority populations.

OBJECTIVE

The objective of the study was to examine the relationship between levels of 25[OH]D and 1,25[OH](2)D and measures of adiposity in Hispanic and African-Americans at baseline and on change in these measures over time.

DESIGN AND SETTING

The Insulin Resistance Atherosclerosis (IRAS) Family Study examined 917 Hispanics and 439 African-Americans at baseline and again 5.3 yr later (n = 1081 at follow-up).

MAIN OUTCOME MEASURE

25[OH]D (nanograms per milliliter) and 1,25[OH](2)D (picograms per milliliter) were measured at baseline. Abdominal sc adipose tissue (SAT), visceral adipose tissue (VAT; both determined by computed tomography scan), and body mass index (BMI) were measured at baseline and follow-up.

RESULTS

25[OH]D was inversely associated with BMI, VAT, and SAT in both populations at baseline (P < 0.001). 25[OH]D was marginally inversely associated with baseline visceral fat to sc fat ratio in African-Americans (P = 0.049) but not Hispanics. 1,25[OH](2)D was inversely associated with BMI (P < 0.0001, P = 0.002) and VAT (P = 0.0005, P = 0.012) in Hispanics and African-Americans, respectively, whereas 1,25[OH](2)D was inversely associated with SAT in Hispanics (P < 0.0001) and with visceral fat to sc fat ratio in African-Americans (P = 0.02). Adjusting for 25[OH]D attenuated these associations; 1,25[OH](2)D remained associated with BMI in both populations (P < 0.05) and with SAT (P = 0.004) in Hispanics. No significant associations between 5-yr change in adiposity and 25[OH]D or 1,25[OH](2)D were seen.

CONCLUSIONS

Vitamin D levels were inversely associated with baseline BMI, SAT, and VAT in Hispanic and African-Americans but were not associated with 5-yr change in adiposity.

Five-year change in visceral adipose tissue quantity in a minority cohort: the Insulin Resistance Atherosclerosis Study (IRAS) family study

OBJECTIVE To describe the 5-year change in visceral adipose tissue (VAT) and subcutaneous adipose tissue (SAT) areas. RESEARCH DESIGN AND METHODS Absolute change in VAT and SAT measured by abdominal computed tomography scans has been obtained at a 5-year interval from African Americans (n = 389) and Hispanic Americans (n = 844), aged 20-69 years, in 10-year age-groups. RESULTS Mean 5-year increases in VAT areas in women were 18, 7, 4, 0.4, and -3 cm(2) for African Americans and 13, 7, 3, 1, and -15 cm(2) for Hispanics, across the 5 age decades (trend not significant). Mean 5-year increases in SAT areas in women were 88, 46, 19, 17, and 14 cm(2) for African Americans and 53, 20, 17, 12, and 1 cm(2) for Hispanics, across the 5 age decades (P < 0.05 for both). Similar trends have been observed in men. CONCLUSIONS Accumulation of abdominal fat is greatest in young adulthood. These data may be useful in identifying subgroups at risk of type 2 diabetes.