Increased insulin resistance and insulin secretion in nondiabetic African-Americans and Hispanics compared with non-Hispanic whites. The Insulin Resistance Atherosclerosis Study

EFFICACY AND SAFETY OF DULAGLUTIDE IN HISPANIC/LATINO PATIENTS WITH TYPE 2 DIABETES IN THE AWARD CLINICAL PROGRAM

OBJECTIVE

The aim of this post hoc analysis was to assess the efficacy and safety of once-weekly dulaglutide in Hispanic/Latino patients with type 2 diabetes (T2D) in phase 3 AWARD trials 1 to 6.

METHODS

Hispanic/Latino data at Week 26 were pooled across studies for each dulaglutide dose to analyze the change from baseline in glycosylated hemoglobin (HbA1c), percent to HbA1c goal, and adverse events (AEs). Change from baseline in HbA1c, change from baseline in weight and hypoglycemia were analyzed by Hispanic/Latino and non-Hispanic/Latino subgroups for each study.

RESULTS

Of the 3,136 patients randomized to dulaglutide 1.5 or 0.75 mg, 949 were reported as having Hispanic/Latino ethnicity. Baseline characteristics were similar for Hispanic/Latino and overall populations, except there were slightly more Hispanic/Latino females and weight was slightly lower for Hispanic/Latino patients. Hispanic/Latino patients receiving dulaglutide 1.5 mg had a reduction in HbA1c of 1.25% (95% confidence interval [CI]: -1.35, -1.15); dulaglutide 0.75 mg had a reduction of 1.07% (95% CI: -1.18, -0.96). Reductions in HbA1c and percent to goal HbA1c <7% and ≤6.5% were similar between Hispanic/Latino patients and the overall population. Weight change and hypoglycemia were similar between Hispanic/Latino and non-Hispanic/Latino subgroups for all studies. Treatment-emergent AEs were consistent with the overall population.

CONCLUSION

Dulaglutide improved glycemic control with the potential for weight loss in Hispanic/Latino patients with T2D. Dulaglutide was well tolerated and had a low risk of hypoglycemia when used without insulin secretagogues or insulin. In the Hispanic/Latino population, dulaglutide efficacy and safety was consistent with that of the overall population.

ABBREVIATIONS

AE = adverse event AWARD = Assessment of Weekly AdministRation of dulaglutide in Diabetes BID = twice daily CARMELA = The Cardiovascular Risk Factor Multiple Evaluation of Latin America CI = confidence interval GLP-1 RA = glucagon-like peptide-1 receptor agonist HbA1c = glycosylated hemoglobin T2D = type 2 diabetes.

Body mass index and glycemic control influence lipoproteins in children with type 1 diabetes

BACKGROUND

Patients with type 1 diabetes mellitus (T1DM) have an extremely high risk of cardiovascular disease (CVD) morbidity and mortality. It is well known that dyslipidemia is a subclinical manifestation of atherosclerosis.

OBJECTIVE

To analyze presence and predicting factors of lipoprotein abnormalities prevalent in children with T1DM and whether race-specific differences exist between non-Hispanic white (NHW) and non-Hispanic black (NHB) in the lipoprotein characteristics.

METHODS

A retrospective electronic chart review including 600 (123 NHB and 477 NHW) T1DM patients aged 7.85 ± 3.75 years who underwent lipoprotein analysis.

RESULTS

Relative to NHW counterparts, NHB T1DM subjects had a higher HbA1c, total cholesterol (TC), low-density lipoprotein cholesterol (LDL-c), apoB 100, lipoprotein (a), and high-density lipoprotein cholesterol (HDL-c), HDL-2, and HDL-3. Body mass index (BMI) was positively associated with TC, LDL-c, apoB 100, and non-HDL-c and inversely associated with HDL, HDL-2, and HDL-3. HbA1c was positively associated with TC, LDL-c, apoB 100, non-HDL-c, and HDL-3. Multilinear regression analysis demonstrated that HbA1c was positively associated with apoB 100 in both NHB and NHW, and BMI was a positive determinant of apoB 100 in NHW only.

CONCLUSION

Poor glycemic control and high BMI may contribute to abnormal lipoprotein profiles. Glycemic control (in NHB and NHW) and weight management (in NHW) may have significant implications in T1DM. ApoB 100 concentrations in subjects with T1DM were determined by modifiable risk factors, BMI, HbA1C, and blood pressure, indicating the importance of adequate weight, glycemic, and blood pressure control for better diabetes care and likely lower CVD risk.

Prevalence and Associated Factors of Insulin Resistance in Adults from Maracaibo City, Venezuela

Background and Aim. Insulin resistance (IR) is a prominent pathophysiologic component in a myriad of metabolic disorders, including obesity, prediabetes, and type 2 diabetes mellitus, which are common in our locality. The objective of this study was to determine the prevalence of IR and factors associated with this condition in an adult population from Maracaibo city, Venezuela. Methodology. A cross-sectional, descriptive study with multistaged randomized sampling was carried out in 2026 adults. IR was defined as HOMA2-IR ≥ 2. A multiple logistic regression model was constructed in order to evaluate factors associated with IR. Results. The prevalence of IR was 46.5% (n = 943), with 46.7% (n = 450) in the general population, 46.4% (n = 493) in females, and 47.90% (n = 970) in males (p = 0.895). IR prevalence tended to increase with age and was significantly greater in subjects aged ≥30 years (χ (2) = 16.726; p = 2.33 × 10(-4)). Employment, alcohol consumption, obesity, high triacylglycerides, low HDL-C, and dysglycemia were associated with greater odds of IR, whereas a high level of physical activity appeared to be weak protective factor against IR. Conclusions. The prevalence of IR is elevated in our locality. The main determinants of this condition appear to be the presence of obesity, high triacylglycerides, low HDL-C, dysglycemia, and alcohol intake.

Improved Performance of Dynamic Measures of Insulin Response Over Surrogate Indices to Identify Genetic Contributors of Type 2 Diabetes: The GUARDIAN Consortium

Type 2 diabetes (T2D) is a heterogeneous disorder with contributions from peripheral insulin resistance and β-cell dysfunction. For minimization of phenotypic heterogeneity, quantitative intermediate phenotypes characterizing basal glucose homeostasis (insulin resistance and HOMA of insulin resistance [HOMAIR] and of β-cell function [HOMAB]) have shown promise in relatively large samples. We investigated the utility of dynamic measures of glucose homeostasis (insulin sensitivity [SI] and acute insulin response [AIRg]) evaluating T2D-susceptibility variants (n = 57) in Hispanic Americans from the GUARDIAN Consortium (n = 2,560). Basal and dynamic measures were genetically correlated (HOMAB-AIRg: ρG = 0.28-0.73; HOMAIR-SI: ρG = -0.73 to -0.83) with increased heritability for the dynamic measure AIRg Significant association of variants with dynamic measures (P < 8.77 × 10(-4)) was observed. A pattern of superior performance of AIRg was observed for well-established loci including MTNR1B (P = 9.46 × 10(-12)), KCNQ1 (P = 1.35 × 10(-4)), and TCF7L2 (P = 5.10 × 10(-4)) with study-wise statistical significance. Notably, significant association of MTNR1B with AIRg (P < 1.38 × 10(-9)) was observed in a population one-fourteenth the size of the initial discovery cohort. These observations suggest that basal and dynamic measures provide different views and levels of sensitivity to discrete elements of glucose homeostasis. Although more costly to obtain, dynamic measures yield significant results that could be considered physiologically "closer" to causal pathways and provide insight into the discrete mechanisms of action.

Influence of race/ethnicity on cardiovascular risk factors in polycystic ovary syndrome, the Dallas Heart Study

OBJECTIVE

Polycystic ovarian syndrome (PCOS) is estimated to affect up to 20% of women. PCOS is associated with insulin resistance and cardiovascular (CV) risk factors. We aimed to evaluate the impact of race/ethnicity on the prevalence of CV risk factors and subclinical predictors of CV events.

DESIGN

Cross-sectional analysis of data collected by the Dallas Heart Study, an urban, population-based cohort oversampled for blacks.

PATIENTS

A previously described cohort of women with PCOS and control subjects of the same racial/ethnic group, matched for age and body mass index.

MEASUREMENTS

Hormonal and clinical measures associated with PCOS and CV risk factors.

RESULTS

The study included 117 women with PCOS and 204 controls. Women with PCOS had significant differences across racial/ethnic groups in the prevalence of hypertension, hypercholesterolaemia, hypertriglyceridaemia and impaired fasting glucose (P < 0·05). Controls showed significant racial/ethnic differences in the prevalence of hypertension and impaired fasting glucose (P < 0·05). The odds of hypertension were significantly greater among women with PCOS than controls after adjusting for race/ethnicity (odds ratio, 1·50 [95% CI, 1·03-2·30]; P = 0·04). However, we did not see an interaction of race/ethnicity that significantly changed CV risk factor prevalence between PCOS and controls. In addition, subclinical measures of CV disease were not different between women with PCOS vs controls, even among hypertensive women.

CONCLUSIONS

Race/ethnicity affects the prevalence of CV risk factors for women with and without PCOS. However, race/ethnicity does not interact with PCOS to additionally increase CV risk factor prevalence or subclinical CV disease.

Tobacco Use, Insulin Resistance, and Risk of Type 2 Diabetes: Results from the Multi-Ethnic Study of Atherosclerosis

INTRODUCTION

Tobacco use is associated with insulin resistance and incident diabetes. Given the racial/ethnic differences in smoking patterns and incident type 2 diabetes our objective was to evaluate the association between tobacco use and insulin resistance (IR) as well as incident type 2 diabetes mellitus in a contemporary multiethnic cohort.

METHODS AND RESULTS

We studied 5,931 Multi- Ethnic Study of Atherosclerosis (MESA) participants who at baseline were free of type 2 diabetes (fasting glucose ≥7.0 mmol/l (126 mg/dl) and/or use of insulin or oral hypoglycemic medications) categorized by self-reported tobacco status and reclassified by urinary cotinine (available in 58% of participants) as never, current or former tobacco users. The association between tobacco use, IR (fasting plasma glucose, insulin, and the homeostatic model assessment of insulin resistance (HOMA-IR)) and incident diabetes over 10 years was evaluated using multivariable linear regression and Cox proportional hazards models, respectively. Mean age of the participants was 62 (±10) years, 46% were male, 41% Caucasian, 12% Chinese, 26% African American and 21% Hispanic/Latino. IR biomarkers did not significantly differ between current, former, and never cigarette users (P >0.10) but showed limited unadjusted differences for users of cigar, pipe and smokeless tobacco (All P <0.05). Fully adjusted models showed no association between dose or intensity of tobacco exposure and any index of IR. When stratified into participants that quit smoking vs. those who continued smoking during the 10-year study there was no difference in serum glucose levels or frequency of diabetes. In fully adjusted models, there was no significant difference in diabetes risk between former or current cigarette smokers compared to never smokers [HR (95% CI) 1.02 (0.77,1.37) and 0.81 (0.52,1.26) respectively].

CONCLUSION

In a contemporary multi-ethnic cohort, there was no independent association between tobacco use and IR or incident type 2 diabetes. The role smoking plays in causing diabetes may be more complicated than originally thought and warrants more in-depth large contemporary multi-ethnic studies.

Do glycemic marker levels vary by race? Differing results from a cross-sectional analysis of individuals with and without diagnosed diabetes

OBJECTIVE

It is well known that A1c varies by race. However, racial differences in other biomarkers of hyperglycemia are less well characterized. The objective of this study was to determine whether average levels of glycemic markers differ by race in adults with and without diagnosed diabetes, before and after accounting for postchallenge glucose.

RESEARCH DESIGN AND METHODS

This cross-sectional study included 2692 middle-aged men and women (5.5% with diagnosed diabetes; 44% African-American; and 56% white) from the Coronary Artery Risk Development in Young Adults Study (2005-2006) who had fasting glucose, 2-hour postchallenge glucose, A1c, glycated albumin, fructosamine, and 1,5-anhydroglucitol (1,5-AG) measured. Multiple linear regression was used to evaluate racial differences in mean levels of each glycemic marker stratified by the diabetes status and adjusted for sociodemographics, cardiovascular factors, and postchallenge glucose.

RESULTS

Among those with diagnosed diabetes, racial differences were not observed for any of the glycemic markers. In contrast, among those without diagnosed diabetes, African-Americans had higher mean levels than whites of A1c (β=0.19% points; 95% CI 0.14 to 0.24), glycated albumin (β=0.82% points; 95% CI 0.68 to 0.97), fructosamine (β=8.68 μmol/L; 95% CI 6.68 to 10.68), and 2-hour glucose (β=3.50 mg/dL; 95% CI 0.10 to 6.90) after multivariable adjustment, whereas there were no statistically significant racial difference in 1,5-AG. The racial differences observed for A1c, glycated albumin, and fructosamine persisted after further adjustment for fasting and 2-hour glucose and were of similar magnitude (SD units).

CONCLUSIONS

Racial differences in glycemic marker levels were evident among middle-aged adults without diagnosed diabetes even after adjustment for postchallenge glucose. Whether these racial differences in biomarkers of hyperglycemia affect the risk of complications warrants additional study.

Disparities in Treatment Uptake and Outcomes of Patients with Obesity in the USA

There are clear and persistent disparities in obesity prevalence within the USA. Some of these disparities fall along racial/ethnic lines; however, there are a number of other social and demographic constructs where obesity disparities are present. In addition to differing rates of obesity across groups, there is growing evidence that subgroups of patients both seek out and respond to obesity treatment differently. This review article explores the epidemiology of obesity disparities, as well as the existing evidence around how different groups may respond to behavioral, medical, and surgical therapies, and potential reasons for differential uptake and response, from culture, to access, to physiology. We find that the vast majority of evidence in this area has focused on the observation that African Americans tend to lose less weight in clinical trials compared to non-Hispanic whites and mainly pertains to behavioral interventions. Moving forward, there will be a need for studies that broaden the notion of health disparity beyond just comparing African Americans and non-Hispanic whites. Additionally, a more thorough examination of the potential for disparate outcomes after medical and surgical treatments of obesity is needed, coupled with the careful study of possible physiologic drivers of differential treatment response.

Associations between body fat distribution, insulin resistance and dyslipidaemia in black and white South African women

Aim

The aim was to examine differences in body fat distribution between premenopausal black and white South African (SA) women and explore the ethnic-specific associations with cardiometabolic risk.

Methods

Body composition, using dual-energy X-ray absorptiometry (DXA) and computerised tomography, insulin resistance (HOMA-IR) and lipid levels were assessed in 288 black and 197 white premenopausal SA women.

Results:

Compared to the white women, black women had less central and more peripheral (lower-body) fat, and lower serum lipid and glucose concentrations, but similar homeostasis models for insulin resistance (HOMA-IR) values. The associations between body fat distribution and HOMA-IR, triglyceride and high-density lipoprotein cholesterol concentrations were similar, while the associations with fasting glucose, total and low-density lipoprotein cholesterol levels differed between black and white women.

Conclusion:

Ethnic differences in body fat distribution are associated, in part, with differences in cardiometabolic risk between black and white SA women.

Long term trends and racial/ethnic disparities in the prevalence of obesity

Obesity is an epidemic associated with higher rates of hypertension, diabetes, and cardiovascular diseases. However, significant racial disparities in the prevalence of obesity have been reported. To evaluate racial disparities and trends in the prevalence of obesity and obesity-related diseases. A population-based retrospective cohort study utilized data from the 1985 to 2011 California Behavioral Risk Factor Survey. Trends in obesity prevalence were stratified by age, sex, race/ethnicity, and socioeconomic factors. Multivariate logistic regression models evaluated independent predictors of obesity. The prevalence of obesity in significantly increased from 1985 to 2011 (8.6 vs. 22.8%, p < 0.001). This increase was seen among men and women, and among all race/ethnic, age, and socioeconomic groups. Hypertension and diabetes also increased during this time period (hypertension 20.7-35.9%; diabetes 4.2-11.2%). Obesity prevalence was highest in blacks and Hispanics, and lowest in Asians (blacks 33.3%; Hispanics 28.8%; Asians 9.0%; p < 0.001). Obesity prevalence was associated with lower education level, lower income, and unemployment status. After adjustments for age, sex, co morbidities, and surrogates of socioeconomic status, the increased risk of obesity in blacks and Hispanics persisted (blacks OR 1.51; Hispanics OR 1.18), whereas Asians were less likely to be obese (OR 0.37). While the overall prevalence of obesity increased from 1985 to 2011, significant racial/ethnic disparities in obesity have developed, with the highest prevalence seen in blacks and Hispanics, and the lowest seen in Asians.

Tissue-Specific and Genetic Regulation of Insulin Sensitivity-Associated Transcripts in African Americans

Integrative multiomics analyses of adipose and muscle tissue transcripts, S, and genotypes revealed novel genetic regulatory mechanisms of insulin resistance in African Americans.

Cardiorespiratory Fitness and Metabolic Syndrome in Postmenopausal African-American Women

We examined the association of cardiorespiratory fitness with metabolic syndrome in overweight/obese postmenopausal African-American women. Pooled baseline data on 170 African-American women from 2 exercise trials were examined. Metabolic syndrome was defined as at least 3 of the following: abdominal obesity, glucose intolerance, hypertension, low high-density lipoprotein cholesterol (HDL-C), and high triglycerides. Cardiorespiratory fitness (VO2peak) was determined using the Bruce treadmill protocol and categorized as: Very Low (VLCRF<18 mL·kg(-1) min(-1)), Low (LCRF=18.0-220-22-22.0 mL·kg(-1) min(-1)), and Moderate (MCRF>22.0 mL·kg(-1) min(-1)). Associations of metabolic syndrome with cardiorespiratory fitness were analyzed using one-way ANOVA and linear regression. VO2peak was significantly lower in the VLCRF compared to the MCRF group. Lower cardiorespiratory fitness was associated with higher prevalence of metabolic syndrome, abdominal obesity, hypertriglyceridemia, and low HDL among overweight/obese postmenopausal African-American women. In fully adjusted models, higher waist circumference and triglycerides were associated with lower VO2peak levels (P<0.01) and higher HDL-C was associated with higher VO2peak levels (P=0.03). Overweight/obese postmenopausal African-American women with very low cardiorespiratory fitness are more likely to have metabolic syndrome, higher body mass index, and unhealthier levels of certain metabolic syndrome components than women with moderate cardiorespiratory fitness.

Myosteatosis increases with aging and is associated with incident diabetes in African ancestry men

OBJECTIVE

Skeletal muscle fat infiltration (known as myosteatosis) is greater in African compared with European ancestry men and may play an important role in the development of type 2 diabetes (T2D). However, prospective studies examining the magnitude of changes in myosteatosis with aging and their metabolic consequences are sparse.

METHODS

Longitudinal changes in peripheral quantitative computed tomography measured calf myosteatosis [intermuscular fat (mm(2) ) and skeletal muscle density as a measure of intramuscular fat (mg/cm(3) )] were examined in 1515 Afro-Caribbean men aged 40+ years recruited without regard to their health status.

RESULTS

During an average of 6.2 years of follow-up, an age-related increase in intermuscular fat and a decrease in skeletal muscle density were observed (all P < 0.0001), which remained significant in those who lost weight, gained weight, or remained weight stable (all P < 0.0001). In addition, muscle density loss accelerated with increasing age (P < 0.0001). Increased intermuscular fat during follow-up was associated with an increased incident risk of T2D independent of factors known to be associated with T2D (odds ratios per 1-SD increase in intermuscular fat = 1.29; 95% CI = 1.08-1.53).

CONCLUSIONS

Our findings suggest that both inter- and intramuscular fat increase with advancing age and that intermuscular fat contributes to development of T2D among African ancestry men.

Racial differences in weight loss, hemoglobin A1C, and blood lipid profiles after Roux-en-Y gastric bypass surgery

BACKGROUND

It is known that African American (AA) patients with obesity achieve less weight loss after Roux-en-Y gastric bypass surgery (RYGB) than their Caucasian (CA) counterparts. However, it is unclear how these differences in weight loss are reflected in clinical outcomes.

OBJECTIVES

To determine the effects of RYGB on hemoglobin A_1c (A_1c) and blood lipids in relationship to the variability in weight loss outcomes in a racially mixed patient population.

SETTING

University medical center.

METHODS

Retrospective analysis of clinical data from electronic medical records of CA, AA, and Hispanic American (HA) patients undergoing RYGB.

RESULTS

We used 2-way cluster analysis and identified 4 distinct weight loss×race clusters. CA patients separated into 2 clusters (45.5% and 28.2% weight loss, respectively), whereas, AA and HA patients separated into 1 cluster each (33.2% and 34.4% weight loss, respectively). Factors that significantly affected weight loss were race, age, gender, and physical activity as well as presence of hypertension and degenerative joint disease. Although all clusters had significant improvements in blood lipids, HA had an increase in total cholesterol (Total-c) and low-density lipoprotein cholesterol (LDL-c) at 2 years after surgery. All clusters had significant decreases in A_1c in the first year. At 2 years after RYGB, A_1c levels remained stable in CA and HA; however, AA had a significant increase. These racial differences in A_1c could not be explained by the smaller weight loss in AA patients.

CONCLUSION

Race is an important factor in the clinical outcomes of RYGB, especially in regard to diabetes control; however, its effect is not completely understood.

Physical activity, sedentary behaviors and the incidence of type 2 diabetes mellitus: the Multi-Ethnic Study of Atherosclerosis (MESA)

BACKGROUND

The association between physical activity (PA), sedentary behavior, and incident diabetes has been assessed in whites but is less well investigated in multiethnic populations.

OBJECTIVE

To assess the association between PA, sedentary behavior, and incident diabetes in the Multi-Ethnic Study of Atherosclerosis.

RESEARCH DESIGN AND METHODS

Incident diabetes was assessed among adults without prevalent baseline diabetes (2000-2002) at 5 in-person examinations between 2002 and 2012. Baseline PA (moderate, vigorous, and exercise-specific; metabolic equivalents of task-hours/week) and sedentary behaviors (television watching, reading; hours/day) were assessed by questionnaire. HRs were estimated using Cox proportional hazard models.

RESULTS

Among 5829 adults (mean age 61.8 years, 54% female, 42% white, 12% Chinese-American, 26% African-American, 21% Hispanic-American), there were 655 incident diabetes cases (median follow-up 11.1 years). After adjustment, diabetes risk was lower in those with brisk or striding compared with none or casual walking pace (HR 0.67; 95% CI 0.54 to 0.84), higher levels of exercise PA (HR for highest vs lowest quartile 0.79; 95% CI 0.63 to 0.98), and any compared with no vigorous PA (HR 0.79; 95% CI 0.66 to 0.95). Race/ethnicity influenced the association of walking pace, exercise PA, and any vigorous PA on diabetes risk, which was only significant among whites. Total leisure sedentary behaviors (HR for highest vs lowest quartile 1.65; 95% CI 1.26 to 2.14) and television watching (HR for highest vs lowest quartile 2.68; 95% CI 1.38 to 5.21) were significantly associated with diabetes risk in multiethnic analyses and were influenced by race/ethnicity.

CONCLUSIONS

These results confirm the importance of PA and sedentary behavior on diabetes risk in a multiethnic population and demonstrate potential variations across race/ethnic groups.

Dietary carbohydrate intake, glycaemic load, glycaemic index and ovarian cancer risk in African-American women

Epidemiological evidence regarding the association between carbohydrate intake, glycaemic load (GL) and glycaemic index (GI) and risk of ovarian cancer has been mixed. Little is known about their impact on ovarian cancer risk in African-American women. Associations between carbohydrate quantity and quality and ovarian cancer risk were investigated among 406 cases and 609 controls using data from the African American Cancer Epidemiology Study (AACES). AACES is an ongoing population-based case-control study of ovarian cancer in African-Americans in the USA. Cases were identified through rapid case ascertainment and age- and site-matched controls were identified by random-digit dialling. Dietary information over the year preceding diagnosis or the reference date was obtained using a FFQ. Multivariable logistic regression models were used to estimate odds ratios and 95% CI adjusted for covariates. The OR comparing the highest quartile of total carbohydrate intake and total sugar intake v. the lowest quartile were 1·57 (95% CI 1·08, 2·28; P trend=0·03) and 1·61 (95% CI 1·12, 2·30; P trend<0·01), respectively. A suggestion of an inverse association was found for fibre intake. Higher GL was positively associated with the risk of ovarian cancer (OR 1·18 for each 10 units/4184 kJ (1000 kcal); 95% CI 1·04, 1·33). No associations were observed for starch or GI. Our findings suggest that high intake of total sugars and GL are associated with greater risk of ovarian cancer in African-American women.

Duration and Degree of Weight Gain and Incident Diabetes in Younger Versus Middle-Aged Black and White Adults: ARIC, CARDIA, and the Framingham Heart Study

OBJECTIVE

To determine whether duration and degree of weight gain are differentially associated with diabetes risk in younger versus middle-aged black and white adults.

RESEARCH DESIGN AND METHODS

We combined data from three cohort studies: Atherosclerosis Risk in Communities (ARIC), Coronary Artery Risk Development in Young Adults (CARDIA), and the Framingham Heart Study. A total of 17,404 participants (56% women; 21% black) were stratified by baseline age (younger: ≥30 and <45 years; middle-aged: ≥45 and <60 years) and examined for incident diabetes (median follow-up 9 years). Duration and degree of gain in BMI were calculated as "BMI-years" above one's baseline BMI.

RESULTS

Diabetes incidence per 1,000 person-years in the younger and middle-aged groups was 7.2 (95% CI 5.7, 8.7) and 24.4 (22.0, 26.8) in blacks, respectively, and 3.4 (2.8, 4.0) and 10.5 (9.9, 11.2) in whites, respectively. After adjusting for sex, baseline BMI and other cardiometabolic factors, and age and race interaction terms, gains in BMI-years were associated with higher risk of diabetes in the younger compared with middle-aged groups: hazard ratios for 1-unit increase in log BMI-years in younger versus middle-aged blacks were 1.18 (P = 0.02) and 1.02 (P = 0.39), respectively (P for interaction by age-group = 0.047), and in whites were 1.35 (P < 0.001) and 1.11 (P < 0.001), respectively (P for interaction by age-group = 0.008).

CONCLUSIONS

Although middle-aged adults have higher rates of diabetes, younger adults are at greater relative risk of developing diabetes for a given level of duration and degree of weight gain.

Ethnic differences in hepatic and systemic insulin sensitivity and their associated determinants in obese black and white South African women

AIMS/HYPOTHESIS

There is evidence to suggest that ectopic fat deposition in liver and skeletal muscle may differ between black and white women resulting in organ-specific differences in insulin sensitivity. Accordingly, the aim of the study was to examine ethnic differences in hepatic and peripheral insulin sensitivity, and the association with hepatic and skeletal muscle lipid content, and skeletal muscle gene expression.

METHODS

In a cross-sectional study including 30 obese premenopausal black and white women, body composition (dual energy x-ray absorptiometry), liver fat and skeletal muscle (soleus and tibialis anterior) fat accumulation (proton-magnetic resonance spectroscopy), skeletal muscle gene expression, insulin sensitivity (two-step isotope labelled, hyperinsulinaemic-euglycaemic clamp with 10 mU m(-2) min(-1) and 40 mU m(-2) min(-1) insulin infusions), and serum adipokines were measured.

RESULTS

We found that, although whole-body insulin sensitivity was not different, obese white women presented with lower hepatic insulin sensitivity than black women (% suppression of endogenous glucose production [% supp EGP], median [interquartile range (IQR)]: 17 [5-51] vs 56 [29-100] %, p = 0.002). While liver fat tended to be lower (p = 0.065) and skeletal muscle fat deposition tended to be higher (p = 0.074) in black compared with white women, associations with insulin sensitivity were only observed in black women (% supp EGP vs liver fat: r = -0.57, p < 0.05 and % supp EGP vs soleus fat: r = -0.56, p < 0.05).

CONCLUSIONS/INTERPRETATION

These findings may suggest that black women are more sensitive to the effects of ectopic lipid deposition than white women.

The Interplay Between Sex, Ethnicity, and Adipose Tissue Characteristics

The obesity epidemic in the USA affects disproportionately women and the ethnic minorities. On the other hand, female sex is traditionally associated with a favorable fat distribution preferentially in the subcutaneous depots of the lower body and with improved endocrine and metabolic function of the adipose tissue. However, these data are derived from predominantly non-Hispanic white populations. This review discusses fat distribution patterns in women of diverse ethnic backgrounds, together with data on the release of adipokines from adipose tissue in these populations. Very little information is available on how the metabolic function of the adipocyte differs depending on ethnicity. Thus, it becomes clear that future clinical and translational research should explicitly discuss and take into account the sex and ethnic background of the populations studied.

Bone Mineral Content as a Driver of Energy Expenditure in Prepubertal and Early Pubertal Boys

OBJECTIVE

To examine the associations of bone and bone-secreted factors with measures of energy metabolism in prepubertal and early pubertal boys.

STUDY DESIGN

Participants in this cross-sectional, observational study included 37 (69% black, 31% white) boys, aged 7-12 years (Tanner stage <III). Dual-energy X-ray absorptiometry was used to measure bone mineral content (BMC) and percent body fat. Indirect calorimetry was used to assess resting energy expenditure (REE). Fasting blood levels of osteocalcin (OCN), fibroblast growth factor 23 (FGF23), insulin, glucose, precursor product of type I collagen (N-terminal pro-peptide) and type I collagen, and C-terminal cross-linked telopeptide were measured. Pearson correlations were performed to evaluate relationships among BMC, OCN, FGF23, fasting insulin and glucose, and REE. Multiple linear regression models were used to test associations between OCN and BMC (independent variables) with fasting insulin and glucose and with REE, adjusting for bone turnover markers and further adjusted for percent body fat.

RESULTS

BMC was correlated with REE and insulin. OCN was correlated with glucose in blacks only (r = 0.45, P < .05). FGF23 was not correlated with any markers of energy metabolism. BMC was associated with insulin level in blacks (β = 0.95, P = .001), which was attenuated by percent body fat (β = 0.47, P = .081). BMC was associated with REE in whites (β = 0.496.7, P < .05) and blacks (β = 619.5, P < .0001); but accounting for percent body fat attenuated the association in whites (β = 413.2, P = .078).

CONCLUSION

Our findings suggest that BMC is a determinant of fasting insulin and REE, and that the contribution of body fat appears to be race-specific. Endocrine effects of FGF23 and OCN on energy metabolism were not apparent.

TRIAL REGISTRATION

Registered with ClinicalTrials.gov: NCT02040740, NCT02040727, and NCT01410643.

Racial/Ethnic Differences in Insulin Resistance and Beta Cell Function: Relationship to Racial Disparities in Type 2 Diabetes among African Americans versus Caucasians

Both biological and sociocultural factors have been implicated in the well-documented racial disparity in incidence and prevalence of type 2 diabetes (T2D) between African Americans (AA) and non-Hispanic whites (NHW). This review examines the extent to which biological differences in glucose metabolism, specifically insulin resistance and beta cell function (BCF), contribute to this disparity. The majority of available data suggests that AA are more insulin resistant and have upregulated BCF compared to NHW. Increasing evidence implicates high insulin secretion as a cause rather than consequence of T2D; therefore, upregulated BCF in AA may specifically confer increased risk of T2D in this cohort. Racial disparities in the metabolic characteristics of T2D have direct implications for the treatment and health consequences of this disease; therefore, future research is needed to determine whether strategies to reduce insulin secretion in AA may prevent or delay T2D and lessen racial health disparities.

Racial Disparities in the Pathogenesis of Type 2 Diabetes and its Subtypes in the African Diaspora: A New Paradigm

The global epidemic of diabetes has extended to the developing countries including Sub-Sahara Africa. In this context, blacks with type 2 diabetes in the African Diaspora continue to manifest 1.5-2 times higher prevalent rates than in their white counterparts. Previous studies have demonstrated that blacks with and without type 2 diabetes have alterations in hepatic and peripheral insulin sensitivity, beta-cell function, and hepatic insulin clearance as well as hepatic glucose dysregulation when compared to whites. In addition, non-diabetic blacks in the African Diaspora manifest multiple metabolic mediators that predict type 2 diabetes and its subtypes. These pathogenic modifiers include differences in subclinical inflammation, oxidative stress burden, and adipocytokines in blacks in the African Diaspora prior to clinical diagnosis. Consequently, blacks in the African Diaspora manifest subtypes of type 2 diabetes, including ketosis-prone diabetes and J type diabetes. Given the diversity of type 2 diabetes in blacks in the African Diaspora, we hypothesize that blacks manifest multiple early pathogenic defects prior to the diagnosis of type 2 diabetes and its subtypes. These metabolic alterations have strong genetic component, which appears to play pivotal and primary role in the pathogenesis of type 2 diabetes and its subtypes in blacks in the African Diaspora. However, environmental factors must also be considered as major contributors to the higher prevalence of type 2 diabetes and its subtypes in blacks in the African Diaspora. These multiple alterations should be targets for early prevention of type 2 diabetes in blacks in the African Diaspora.

Genetic Variants Associated With Quantitative Glucose Homeostasis Traits Translate to Type 2 Diabetes in Mexican Americans: The GUARDIAN (Genetics Underlying Diabetes in Hispanics) Consortium

Insulin sensitivity, insulin secretion, insulin clearance, and glucose effectiveness exhibit strong genetic components, although few studies have examined their genetic architecture or influence on type 2 diabetes (T2D) risk. We hypothesized that loci affecting variation in these quantitative traits influence T2D. We completed a multicohort genome-wide association study to search for loci influencing T2D-related quantitative traits in 4,176 Mexican Americans. Quantitative traits were measured by the frequently sampled intravenous glucose tolerance test (four cohorts) or euglycemic clamp (three cohorts), and random-effects models were used to test the association between loci and quantitative traits, adjusting for age, sex, and admixture proportions (Discovery). Analysis revealed a significant (P < 5.00 × 10(-8)) association at 11q14.3 (MTNR1B) with acute insulin response. Loci with P < 0.0001 among the quantitative traits were examined for translation to T2D risk in 6,463 T2D case and 9,232 control subjects of Mexican ancestry (Translation). Nonparametric meta-analysis of the Discovery and Translation cohorts identified significant associations at 6p24 (SLC35B3/TFAP2A) with glucose effectiveness/T2D, 11p15 (KCNQ1) with disposition index/T2D, and 6p22 (CDKAL1) and 11q14 (MTNR1B) with acute insulin response/T2D. These results suggest that T2D and insulin secretion and sensitivity have both shared and distinct genetic factors, potentially delineating genomic components of these quantitative traits that drive the risk for T2D.

Activation of innate immunity modulates insulin sensitivity, glucose effectiveness and pancreatic β-cell function in both African ancestry and European ancestry healthy humans

OBJECTIVE

Insulin resistance is a risk factor for type 2 diabetes, and is associated with inflammatory cardiometabolic disease. Given differences between African ancestry (AA) and European ancestry (EA) in the epidemiology of type 2 diabetes as well as in response to inflammatory stress, we investigated potential race differences in glucose homeostasis responses during experimental endotoxemia in humans.

METHODS

Healthy volunteers (age 18-45 years, BMI 18-30 kg/m(2), 47% female, African-ancestry (AA, n=42) and European-ancestry (EA, n=106)) were recruited as part of the Genetics of Evoked Responses to Niacin and Endotoxemia (GENE) Study. Subjects underwent an inpatient endotoxin challenge (1 ng/kg LPS) and two frequently-sampled intravenous glucose tolerance tests (FSIGTT). Insulin and glucose values obtained during FSIGTT pre- and 24-hours post-LPS were analyzed using the minimal model.

RESULTS

FSIGTT derived insulin sensitivity index (SI), disposition index (DI) and glucose effectiveness (SG) decreased significantly following LPS (p<0.0001) while the acute insulin response to glucose (AIR(g)) increased (p<0.0001). Although expected race differences were observed in glucose homeostasis parameters at baseline prior to LPS e.g., lower SI (2.5 vs. 4.1 μU/L/min, p<0.0001) but higher AIR(g) (median 848 vs. 290 μU/L/min, p<0.0001) in AA vs. EA, the changes in glucose homeostasis responses to LPS were directionally and proportionally consistent across race e.g., SI median -35% in EA and -29% in AA and AIR(g) median +17% in EA and +26% in AA.

CONCLUSION

Both EA and AA samples modulated glucose and insulin homeostasis similarly during endotoxemia.

IMPLICATIONS

Race differences in response to environmental inflammatory stress are unlikely to be a substantial contributor to the observed difference in diabetes incidence and complications between EA and AA.

Relationship of pericardial fat with biomarkers of inflammation and hemostasis, and cardiovascular disease: the Multi-Ethnic Study of Atherosclerosis

OBJECTIVE

Pericardial fat may increase the risk of cardiovascular disease (CVD) by increasing circulating levels of inflammation and hemostasis biomarkers. We investigated the associations of pericardial fat with inflammation and hemostasis biomarkers, as well as incident CVD events, and whether there are any ethnic differences in these associations.

METHODS

We analyzed results from 6415 participants from the Multi-Ethnic Study of Atherosclerosis who had measurements of pericardial fat volume and circulating levels of C-reactive protein (CRP), fibrinogen, interleukin (IL)-6, factor VIII, D-dimer and plasmin-antiplasmin complex (PAP), and had a mean follow-up period of 9.5 years. Incident CVD event was defined as any adjudicated CVD event.

RESULTS

After adjusting for confounding factors, pericardial fat volume was positively associated with natural log (ln) of IL-6 levels, but inversely associated with ln D-dimer and ln PAP levels (β = 0.067, -0.032, and -0.105 respectively, all P < 0.05). Although a larger pericardial fat volume was associated with a higher risk of incident CVD, the association was attenuated to borderline significance after adjusting for traditional cardiovascular risk factors (P = 0.050). There was a borderline significant ethnicity interaction (P = 0.080), whereby the association between pericardial fat volume and incident CVD was significant in Hispanic Americans, even after further adjusting for biomarkers of inflammation and hemostasis (hazard ratio = 1.31 per SD increase, 95% confidence interval 1.09-1.57, P = 0.004).

CONCLUSION

Pericardial fat was associated with several inflammation and hemostasis biomarkers. The association of pericardial fat with incident CVD events was independent of these biomarkers only among Hispanic Americans.

Carbohydrate intake, glycemic index and prostate cancer risk

BACKGROUND

Reported associations between dietary carbohydrate and prostate cancer (PC) risk are poorly characterized by race.

METHODS

We analyzed the association between carbohydrate intake, glycemic index (GI), and PC risk in a study of white (N = 262) and black (N = 168) veterans at the Durham VA Hospital. Cases were 156 men with biopsy-confirmed PC and controls (N = 274) had a PSA test but were not recommended for biopsy. Diet was assessed before biopsy with a self-administered food frequency questionnaire. Logistic regression models were used to estimate PC risk.

RESULTS

In multivariable analyzes, higher carbohydrate intake, measured as percent of energy from carbohydrates, was associated with reduced PC risk (3rd vs. 1st tertile, OR = 0.41, 95% CI 0.21-0.81, P = 0.010), though this only reached significance in white men (p-trend = 0.029). GI was unrelated to PC risk among all men, but suggestively linked with reduced PC risk in white men (p-trend = 0.066) and increased PC risk in black men (p-trend = 0.172), however, the associations were not significant. Fiber intake was not associated with PC risk (all p-trends > 0.55). Higher carbohydrate intake was associated with reduced risk of high-grade (p-trend = 0.016), but not low-grade PC (p-trend = 0.593).

CONCLUSION

Higher carbohydrate intake may be associated with reduced risk of overall and high-grade PC. Future larger studies are needed to confirm these findings.

Integrative network analysis reveals different pathophysiological mechanisms of insulin resistance among Caucasians and African Americans

Background

African Americans (AA) have more pronounced insulin resistance and higher insulin secretion than European Americans (Caucasians or CA) when matched for age, gender, and body mass index (BMI). We hypothesize that physiological differences (including insulin sensitivity [S_I]) between CAs and AAs can be explained by co-regulated gene networks in tissues involved in glucose homeostasis.

Methods

We performed integrative gene network analyses of transcriptomic data in subcutaneous adipose tissue of 99 CA and 37 AA subjects metabolically characterized as non-diabetic, with a range of S_I and BMI values.

Results

Transcripts negatively correlated with S_I in only the CA or AA subjects were enriched for inflammatory response genes and integrin-signaling genes, respectively. A sub-network (module) with TYROBP as a hub enriched for genes involved in inflammatory response (corrected p = 1.7E-26) was negatively correlated with S_I (r = −0.426, p = 4.95E-04) in CA subjects. S_I was positively correlated with transcript modules enriched for mitochondrial metabolism in both groups. Several S_I-associated co-expressed modules were enriched for genes differentially expressed between groups. Two modules involved in immune response to viral infections and function of adherens junction, are significantly correlated with S_I only in CAs. Five modules involved in drug/intracellular transport and oxidoreductase activity, among other activities, are correlated with S_I only in AAs. Furthermore, we identified driver genes of these race-specific S_I-associated modules.

Conclusions

S_I-associated transcriptional networks that were deranged predominantly in one ethnic group may explain the distinctive physiological features of glucose homeostasis among AA subjects.

Electronic supplementary material

The online version of this article (doi:10.1186/s12920-015-0078-0) contains supplementary material, which is available to authorized users.

Prevalence of metabolic syndrome and obesity-associated hypertension in the racial ethnic minorities of the United States

Metabolic syndrome (MetS) is a clinical condition that includes multiple cardiovascular disease risk factors, including obesity, high blood pressure or hypertension, dyslipidemia, and abnormal glucose metabolism. The core metabolic abnormality in MetS is insulin resistance, or impaired insulin-mediated glucose regulation that results in elevated plasma insulin concentration. MetS greatly increases the risk for diabetes, atherosclerosis, and adverse metabolic and cardiovascular outcomes. The syndrome is present in over 25 % of adults in the U.S., with higher rates among racial/ethnic minority groups. Although commonly associated with adult diseases and aging, MetS has also been described in children and adolescents, but at a much lower prevalence of approximately 4-5 %. Because obesity is a key component of the syndrome, the growing childhood epidemic has raised awareness of MetS in children. The rate of MetS among obese children and adolescents is approximately 30 %, with similar racial/ethnic disparity among minority groups as among adults.

A lower-carbohydrate, higher-fat diet reduces abdominal and intermuscular fat and increases insulin sensitivity in adults at risk of type 2 diabetes

BACKGROUND

Obesity, particularly visceral and ectopic adiposity, increases the risk of type 2 diabetes.

OBJECTIVE

The aim of this study was to determine if restriction of dietary carbohydrate is beneficial for body composition and metabolic health.

METHODS

Two studies were conducted. In the first, 69 overweight/obese men and women, 53% of whom were European American (EA) and 47% of whom were African American (AA), were provided with 1 of 2 diets (lower-fat diet: 55%, 18%, and 27% of energy from carbohydrate, protein, and fat, respectively; lower-carbohydrate diet: 43%, 18%, and 39%, respectively) for 8 wk at a eucaloric level and 8 wk at a hypocaloric level. In the second study, 30 women with polycystic ovary syndrome (PCOS) were provided with 2 diets (lower-fat diet: 55%, 18%, and 27% of energy from carbohydrate, protein, and fat, respectively; lower-carbohydrate diet: 41%, 19%, and 40%, respectively) at a eucaloric level for 8 wk in a random-order crossover design.

RESULTS

As previously reported, among overweight/obese adults, after the eucaloric phase, participants who consumed the lower-carbohydrate vs. the lower-fat diet lost more intra-abdominal adipose tissue (IAAT) (11 ± 3% vs. 1 ± 3%; P < 0.05). After weight loss, participants who consumed the lower-carbohydrate diet had 4.4% less total fat mass. Original to this report, across the entire 16-wk study, AAs lost more fat mass with a lower-carbohydrate diet (6.2 vs. 2.9 kg; P < 0.01), whereas EAs showed no difference between diets. As previously reported, among women with PCOS, the lower-carbohydrate arm showed decreased fasting insulin (-2.8 μIU/mL; P < 0.001) and fasting glucose (-4.7 mg/dL; P < 0.01) and increased insulin sensitivity (1.06 arbitrary units; P < 0.05) and "dynamic" β-cell response (96.1 · 10(9); P < 0.001). In the lower-carbohydrate arm, women lost both IAAT (-4.8 cm(2); P < 0.01) and intermuscular fat (-1.2 cm(2); P < 0.01). In the lower-fat arm, women lost lean mass (-0.6 kg; P < 0.05). Original to this report, after the lower-carbohydrate arm, the change in IAAT was positively associated with the change in tumor necrosis factor α (P < 0.05).

CONCLUSION

A modest reduction in dietary carbohydrate has beneficial effects on body composition, fat distribution, and glucose metabolism. This trial was registered at clinicaltrials.gov as NCT00726908 and NCT01028989.

Identification of putative biomarkers for prediabetes by metabolome analysis of rat models of type 2 diabetes

Biomarkers for the development of type 2 diabetes (T2D) are useful for prediction and intervention of the disease at earlier stages. In this study, we performed a longitudinal study of changes in metabolites using an animal model of T2D, the spontaneously diabetic Torii (SDT) rat. Fasting plasma samples of SDT and control Sprague-Dawley (SD) rats were collected from 6 to 24 weeks of age, and subjected to gas chromatography-mass spectrometry-based metabolome analysis. Fifty-nine hydrophilic metabolites were detected in plasma samples, including amino acids, carbohydrates, sugars and organic acids. At 12 weeks of age, just before the onset of diabetes in SDT rats, the amounts of nine of these metabolites (asparagine, glutamine, glycerol, kynurenine, mannose, n-alpha-acetyllysine, taurine, threonine, and tryptophan) in SDT rats were significantly different from those in SD rats. In particular, metabolites in the tryptophan metabolism pathway (tryptophan and kynurenine) were decreased in SDT rats at 12 weeks of age and later. The lower tryptophan and kynurenine levels in the prediabetic state and later were further confirmed by a replication study on SDT rats and by a longitudinal study on another animal model of T2D, the Otsuka Long-Evans Tokushima Fatty rat. Our data indicate that tryptophan and its metabolites are potential biomarkers for prediabetes and that tryptophan metabolism may be a potential target of intervention for treatment of the disease.

Cardiovascular risk in Gullah African Americans with high familial risk of type 2 diabetes mellitus: project SuGAR

OBJECTIVES

To determine the prevalence of cardiovascular disease, levels of cardiovascular risk factors, and extent of preventive care in Gullah African Americans with a high familial risk of type 2 diabetes mellitus.

METHODS

Between 1995 and 2003, 1321 Gullah African Americans with a high prevalence of diabetes mellitus from the South Carolina Sea Islands consented to and enrolled in the Sea Islands Genetic African American Registry (Project SuGAR). A cross-sectional analysis of cardiometabolic risk, preventive care, and self-reported cardiovascular disease was conducted.

RESULTS

Cardiometabolic risk factor levels were high and vascular disease was prevalent. Among the subjects with diabetes mellitus, the mean disease duration was 10.5 years; approximately one-third reported reduced vision or blindness; and >80% reported numbness, pain, or burning in their feet. Preventive diabetes care was limited, with <60%, <25%, and <40% seeing an ophthalmologist, podiatrist, and dentist, respectively, within the past year. Only 54.4% of women and 39.3% of men reported daily glucose monitoring.

CONCLUSIONS

As the largest existing study of Gullah individuals, our study offers insight into not only the level of cardiovascular risk in this population but also the pathophysiological mechanisms central to ancestral differences in cardiometabolic risk in the broader African American population.

Adolescent and adult African Americans have similar metabolic dyslipidemia

BACKGROUND

African Americans (AAs) have lower triglyceride (TG) and higher high-density lipoprotein cholesterol (HDL-C) than other ethnic groups; yet, they also have higher risk for developing diabetes mellitus despite the strong relationship of dyslipidemia with insulin resistance. No studies directly compare adolescents and adults with regard to relationships among dyslipidemia, high-sensitivity C-reactive protein (hs-CRP), and insulin resistance. Here, we compare AA adolescents to adults with regard to the relationships of adiposity-related lipid risk markers (TG-to-HDL ratio and non-HDL-C) with body mass index (BMI), waist circumference (WC), homeostasis model of insulin resistance (HOMA), and hs-CRP.

METHODS

Two cohorts of healthy AA were recruited from the same urban community. Participants in each cohort were stratified by TG-to-HDL ratio (based on adult tertiles) and non-HDL-C levels. BMI, WC, HOMA, and hs-CRP were compared in adolescents and adults in the low-, middle-, and high-lipid strata.

RESULTS

Prevalence of TG-to-HDL ratio greater than 2.028 (high group) was 16% (44 of 283) in adolescents and 33% (161 of 484) in adults; prevalence of non-HDL-C above 145 and 160, respectively, was 8% (22 of 283) in adolescents and 12% (60 of 484) in adults. Values of hs-CRP were lower, and HOMA values were higher in adolescents (both P < .01). As both TG-to-HDL ratio and non-HDL-C strata increased, BMI, WC, HOMA, and hs-CRP increased in both adolescents and adults. In the high TG-to-HDL ratio and non-HDL-C groups, BMI and WC were similar in adolescents vs adults (BMI, 34 kg/m(2) vs 32 kg/m(2); WC, 101 cm vs 101 cm). After adjusting for non-HDL-C and other covariates, a 2-fold increase in TG-to-HDL ratio was associated with increases of 10.4% in hs-CRP (95% CI, 1.1%-20.5%) and 24.2% in HOMA (95% CI, 16.4%-32.6%). Non-HDL-C was not significant in models having TG-to-HDL ratio.

CONCLUSION

The elevated TG-to-HDL ratio is associated with similar inflammation and metabolic risk relationships in adolescent and adult AAs.

Trajectories of metabolic syndrome development in young adults

Background

Metabolic syndrome (MetS) is a constellation of metabolic aberrations that collectively increase the risk for cardiovascular disease and type 2 diabetes. Greater understanding of MetS developments may provide insight into targeted prevention strategies for individuals at greatest risk. The purpose of this study was to i) identify distinct patterns of longitudinal MetS development and; ii) develop a character profile that differentiates groups by level of MetS risk.

Methods and Results

Data from the Coronary Artery Risk Development in Young Adults (CARDIA) study (n = 3 804; 18–30 y) was obtained by limited access application from the National Heart, Lung, and Blood Institute and used for this analysis. MetS, as defined by the Harmonized criteria, was assessed over a 20 year follow-up period. Group-level trajectory analysis identified 4 distinct groups with varying rates of component development [No (23.8% of sample); Low (33.5%); Moderate (35.3%); and High MetS (7.4%)]. After adjusting for covariates, individuals in the At-Risk groups (Low, Moderate and High MetS) were more likely to be of black ethnicity (1.37, 1.14–1.66), have a family history of cardiovascular disease (1.61, 1.31–1.97) and history of dieting (1.69, 1.20–2.39) when compared to the No Risk trajectory group (No MetS). Conversely, increasing baseline education (0.76, 0.65–0.89) and aerobic fitness (0.55, 0.47–0.64) was inversely associated with At-Risk group membership.

Conclusions

Results suggest distinct profiles of MetS development that can be identified by baseline risk factors. Further research is necessary to understand the clinical implication of intermediate MetS development groups with respect to overall cardiometabolic risk.

Prevalence and risk factors of type 2 diabetes in older Vietnam-born Australians

Vietnamese immigrants in Australia represent the second largest Vietnamese community in developed countries, following the United States. However, limited information is available about prevalence of type 2 diabetes (T2D) and the relative roles of socio-demographic characteristics, lifestyle factors, and Vietnamese ethnicity per se in this population. This study investigated the prevalence of T2D and its risk factors in older Vietnam-born Australians, in comparison to native-born Australians. The study used baseline questionnaire data from 787 Vietnam- and 196,866 Australia-born individuals (≥45 years), who participated in the 45 and Up Study, which is Australia's largest population-based cohort study. Country of birth specific prevalence of T2D and its risk factors were age-standardised to the 2006 Australian population (≥45 years). Multivariable logistic regression models were built for each group to assess the relationship between T2D and socio-demographic characteristics, family history of diabetes, lifestyle factors and health status. Compared to Australia-born counterparts, Vietnam-born individuals had significantly (p < 0.001) higher age-standardised prevalence of T2D (14.7 vs 7.4 %) and significantly (p < 0.001) lower levels of vegetable consumption (≥5 serves/day, 19.4 vs 33.5 %), physical activity (≥5 sessions/week, 68.7 vs 78.5 %) and overweight and obesity (body mass index ≥25 kg/m(2), 21.5 vs 62.7 %). The increased risk of T2D associated with a family history of diabetes for Vietnam-born people [adjusted odds ratio (OR) 7.14, 95 % CI 4.15-12.28] was almost double that for Australia-born people (OR 3.77, 95 % CI 3.63-3.90). The patterns of association between T2D and other factors were similar between the two groups. The findings suggest a genetic predisposition to T2D in people of Vietnamese ethnicity. Reducing lifestyle risk factors for diabetes and better management of diabetes are priorities for Vietnam-born populations.

Multiple metabolic genetic risk scores and type 2 diabetes risk in three racial/ethnic groups

CONTEXT/RATIONALE: Meta-analyses of genome-wide association studies have identified many single-nucleotide polymorphisms associated with various metabolic and cardiovascular traits, offering us the opportunity to learn about and capitalize on the links between cardiometabolic traits and type 2 diabetes (T2D).

DESIGN

In multiple datasets comprising over 30 000 individuals and 3 ethnic/racial groups, we calculated 17 genetic risk scores (GRSs) for glycemic, anthropometric, lipid, hemodynamic, and other traits, based on the results of recent trait-specific meta-analyses of genome-wide association studies, and examined associations with T2D risk. Using a training-testing procedure, we evaluated whether additional GRSs could contribute to risk prediction.

RESULTS

In European Americans, we find that GRSs for T2D, fasting glucose, fasting insulin, and body mass index are associated with T2D risk. In African Americans, GRSs for T2D, fasting insulin, and waist-to-hip ratio are associated with T2D. In Hispanic Americans, GRSs for T2D and body mass index are associated with T2D. We observed a trend among European Americans suggesting that genetic risk for hyperlipidemia is inversely associated with T2D risk. The use of additional GRSs resulted in only small changes in prediction accuracy in multiple independent validation datasets.

CONCLUSIONS

The analysis of multiple GRSs can shed light on T2D etiology and how it varies across ethnic/racial groups. Our findings using multiple GRSs are consistent with what is known about the differences in T2D pathogenesis across racial/ethnic groups. However, further work is needed to understand the putative inverse correlation of genetic risk for hyperlipidemia and T2D risk and to develop ethnic-specific GRSs.

Status of cardiovascular disease and stroke in Hispanics/Latinos in the United States: a science advisory from the American Heart Association

BACKGROUND AND PURPOSE

This American Heart Association (AHA) scientific statement provides a comprehensive overview of current evidence on the burden cardiovascular disease (CVD) among Hispanics in the United States. Hispanics are the largest minority ethnic group in the United States, and their health is vital to the public health of the nation and to achieving the AHA's 2020 goals. This statement describes the CVD epidemiology and related personal beliefs and the social and health issues of US Hispanics, and it identifies potential prevention and treatment opportunities. The intended audience for this statement includes healthcare professionals, researchers, and policy makers.

METHODS

Writing group members were nominated by the AHA's Manuscript Oversight Committee and represent a broad range of expertise in relation to Hispanic individuals and CVD. The writers used a general framework outlined by the committee chair to produce a comprehensive literature review that summarizes existing evidence, indicate gaps in current knowledge, and formulate recommendations. Only English-language studies were reviewed, with PubMed/MEDLINE as our primary resource, as well as the Cochrane Library Reviews, Centers for Disease Control and Prevention, and the US Census data as secondary resources. Inductive methods and descriptive studies that focused on CVD outcomes incidence, prevalence, treatment response, and risks were included. Because of the wide scope of these topics, members of the writing committee were responsible for drafting individual sections selected by the chair of the writing committee, and the group chair assembled the complete statement. The conclusions of this statement are the views of the authors and do not necessarily represent the official view of the AHA. All members of the writing group had the opportunity to comment on the initial drafts and approved the final version of this document. The manuscript underwent extensive AHA internal peer review before consideration and approval by the AHA Science Advisory and Coordinating Committee.

RESULTS

This statement documents the status of knowledge regarding CVD among Hispanics and the sociocultural issues that impact all subgroups of Hispanics with regard to cardiovascular health. In this review, whenever possible, we identify the specific Hispanic subgroups examined to avoid generalizations. We identify specific areas for which current evidence was less robust, as well as inconsistencies and evidence gaps that inform the need for further rigorous and interdisciplinary approaches to increase our understanding of the US Hispanic population and its potential impact on the public health and cardiovascular health of the total US population. We provide recommendations specific to the 9 domains outlined by the chair to support the development of these culturally tailored and targeted approaches.

CONCLUSIONS

Healthcare professionals and researchers need to consider the impact of culture and ethnicity on health behavior and ultimately health outcomes. There is a need to tailor and develop culturally relevant strategies to engage Hispanics in cardiovascular health promotion and cultivate a larger workforce of healthcare providers, researchers, and allies with the focused goal of improving cardiovascular health and reducing CVD among the US Hispanic population.

Fasting insulin sensitivity indices are not better than routine clinical variables at predicting insulin sensitivity among Black Africans: a clamp study in sub-Saharan Africans

BACKGROUND

We aimed to evaluate the predictive utility of common fasting insulin sensitivity indices, and non-laboratory surrogates [BMI, waist circumference (WC) and waist-to-height ratio (WHtR)] in sub-Saharan Africans without diabetes.

METHODS

We measured fasting glucose and insulin, and glucose uptake during 80/mU/m2/min euglycemic clamp in 87 Cameroonians (51 men) aged (SD) 34.6 (11.4) years. We derived insulin sensitivity indices including HOMA-IR, quantitative insulin sensitivity check index (QUICKI), fasting insulin resistance index (FIRI) and glucose-to-insulin ratio (GIR). Indices and clinical predictors were compared to clamp using correlation tests, robust linear regressions and agreement of classification by sex-specific thirds.

RESULTS

The mean insulin sensitivity was M = 10.5 ± 3.2 mg/kg/min. Classification across thirds of insulin sensitivity by clamp matched with non-laboratory surrogates in 30-48% of participants, and with fasting indices in 27-51%, with kappa statistics ranging from -0.10 to 0.26. Fasting indices correlated significantly with clamp (/r/=0.23-0.30), with GIR performing less well than fasting insulin and HOMA-IR (both p < 0.02). BMI, WC and WHtR were equal or superior to fasting indices (/r/=0.38-0.43). Combinations of fasting indices and clinical predictors explained 25-27% of variation in clamp values.

CONCLUSION

Fasting insulin sensitivity indices are modest predictors of insulin sensitivity measured by euglycemic clamp, and do not perform better than clinical surrogates in this population.

Insulin secretory capacity and insulin sensitivity in impaired fasting glucose in Japanese

Aims/Introduction:  Impaired fasting glucose (IFG) increases the risk of developing diabetes mellitus (DM). This study was carried out to characterize Japanese patients who have fasting glucose levels (FPG) between 100 and 109 mg/dL (IFG_100–109).

Materials and Methods:  A total of 1383 Japanese participants were examined by oral glucose tolerance test. We compared insulin secretory capacity (insulinogenic index) and insulin sensitivity (ISI composite) of IFG_100–109/normal glucose tolerance (NGT; 100 ≤ FPG < 110 mg/dL and 2‐h postchallenge glucose level (2‐hPG) < 140 mg/dL) with NGT (100 mg/dL < FPG and 2‐hPG < 140 mg/dL) and IFG_110–125/NGT (110 ≤ FPG < 126 mg/dL and 2‐hPG < 140 mg/dL). In addition, IFG_100–109 patients were analyzed in three subgroups according to glucose intolerance by 2‐hPG.

Results:  Of the three categories of IFG_100–109, IFG_100–109/DM had the lowest insulinogenic index despite an ISI composite showing only a small decline from IFG_100–109/NGT through IFG_100–109/IGT (100 ≤ FPG < 110 mg/dL and 140 ≤ 2‐hPG < 200 mg/dL) to IFG_100–109/DM (100 ≤ FPG < 110 mg/dL and 200 mg/dL < 2‐hPG). By multiple regression analysis, the insulinogenic index showed a significant relationship with 2‐h PG levels. Both insulinogenic index and ISI composite were decreased significantly from NGT through IFG_100–109/NGT to IFG_110–125/NGT.

Conclusions:  Although impaired early‐phase insulin secretion plays the more important role in the elevation of postchallenge glucose in IFG_100–109 patients, both impaired early‐phase insulin secretion and decreased insulin sensitivity are involved in the deterioration of FPG in Japanese. In addition, insulin secretory defect and decreased insulin sensitivity already have begun in patients with IFG_100–109.(J Diabetes Invest, doi: 10.1111/j.2040‐1124.2012.00201.x, 2012)

Ethnic disparities in the prevalence of the metabolic syndrome in American adults: data from the Examination of National Health and Nutrition Examination Survey 1999-2010

Data from the National Health and Nutrition Examination Survey were stratified by weight, gender, and ethnicity for six survey years from 1999 to 2010 for variables that satisfy the criteria for metabolic syndrome (MS). Results showed that 34% of the US adult population had MS. No significant gender disparities in MS prevalence were found. Black men had a significantly lower prevalence of MS than Black women and White men from 1999 to 2008 (P < 0.05). Women had a 60% higher abdominal adiposity than men in the US population (P = 0.00048; pregnant females were excluded). Although there seem to be ethnic differences in the prevalence of MS, the expression of MS is not a sufficient risk to culminate in cardiovascular disease; rather, nutritional, genetic, and environmental factors are necessary to finalize its expression into overt disease.

Insulin sensitivity and insulin clearance are heritable and have strong genetic correlation in Mexican Americans

OBJECTIVE

The GUARDIAN (Genetics UndeRlying DIAbetes in HispaNics) consortium is described, along with heritability estimates and genetic and environmental correlations of insulin sensitivity and metabolic clearance rate of insulin (MCRI).

METHODS

GUARDIAN is comprised of seven cohorts, consisting of 4,336 Mexican-American individuals in 1,346 pedigrees. Insulin sensitivity (SI ), MCRI, and acute insulin response (AIRg) were measured by frequently sampled intravenous glucose tolerance test in four cohorts. Insulin sensitivity (M, M/I) and MCRI were measured by hyperinsulinemic-euglycemic clamp in three cohorts. Heritability and genetic and environmental correlations were estimated within the family cohorts (totaling 3,925 individuals) using variance components.

RESULTS

Across studies, age, and gender-adjusted heritability of insulin sensitivity (SI , M, M/I) ranged from 0.23 to 0.48 and of MCRI from 0.35 to 0.73. The ranges for the genetic correlations were 0.91 to 0.93 between SI and MCRI; and -0.57 to -0.59 for AIRg and MCRI (all P < 0.0001). The ranges for the environmental correlations were 0.54 to 0.74 for SI and MCRI (all P < 0.0001); and -0.16 to -0.36 for AIRg and MCRI (P < 0.0001-0.06).

CONCLUSIONS

These data support a strong familial basis for insulin sensitivity and MCRI in Mexican Americans. The strong genetic correlations between MCRI and SI suggest common genetic determinants.

Sugar-sweetened beverages and body weight

PURPOSE OF REVIEW

Given the high prevalence of obesity in the USA, much recent attention has focused on dietary strategies for weight control. Several medical and scientific societies currently recommend reducing consumption of sugar-sweetened beverages (SSBs). However, the evidence base for a public health recommendation has been a topic of debate. The purpose of this review is not to underscore the debate but rather to consider how recently published data pertaining to SSBs contribute to the evidence base for preventing and treating obesity, with application to caring for patients.

RECENT FINDINGS

Consumption of SSBs remains prevalent in the USA. Emerging data from epidemiological studies and clinical trials indicate that consumption contributes to positive energy balance and reducing consumption has beneficial effects on body weight. Some individuals may be more susceptible to the adverse effects of consuming SSBs owing to their ethnicity or genetic predisposition. Plausible physiological mechanisms link consumption of SSBs with weight control.

SUMMARY

Available data provide an evidence base for counselling patients to reduce consumption of SSBs. Nevertheless, additional research is needed to strengthen the evidence base, particularly studies aimed at understanding susceptibility to the adverse effects of consuming SSBs on body weight and mechanisms for these effects.

Determinants of successful glycemic control among participants in the BARI 2D trial: a post-hoc analysis

OBJECTIVE

The BARI 2D trial compared insulin provision (IP) versus insulin sensitization (IS) for the primary outcome of total mortality in participants with T2DM and cardiovascular disease (CVD). In this analysis we examine baseline characteristics that are associated with successful long-term glycemic control.

RESEARCH DESIGN AND METHODS

In a 2×2 factorial design, 2368 participants were randomized to either IP or IS therapy, and to either prompt revascularization with medical therapy or medical therapy alone. Successful long-term glycemic control (success) was defined by simultaneously meeting 1) a mean HbA1c level of <7.0% after each participant's third year of follow-up period, and 2) adherence with medications only from the assigned glycemic treatment arm during >80% of the BARI 2D follow-up. The association between baseline variables and success was determined using unadjusted and adjusted logistic regression models.

RESULTS

1917 participants (962 IP and 955 IS participants) had sufficiently long follow-up and data for this analysis. Among these IP and IS participants, 235 and 335 participants met both criteria of success, respectively (p<0.001). Those not on insulin at entry had higher odds of success (OR 2.25; CI 1.79-2.82) when treated with IS versus IP medications, irrespective of baseline HbA1c levels. Younger age, shorter duration of T2DM, and lower HbA1c at baseline were also each independently associated with higher success when treated with IS versus IP medications.

CONCLUSION

Patients similar to those in the BARI 2D trial may have a higher chance of achieving success with IS versus IP medications if they are younger, have shorter duration of T2DM, have lower HbA1c levels, have moderate or strenuous physically activity, and are not on insulin. In contrast, increasing age, longer duration of T2DM, higher HbA1c, and insulin therapy are associated with increased chance of success if treated with IP medications.

Efficacy and safety of linagliptin in Hispanic/Latino patients with type 2 diabetes mellitus: a pooled analysis from six randomized placebo-controlled phase 3 trials

OBJECTIVE

The number of individuals diagnosed with type 2 diabetes mellitus is expected to rise disproportionately in Hispanic/Latino populations. We therefore aimed to assess the efficacy and safety of the dipeptidyl peptidase-4 inhibitor linagliptin specifically in Hispanic/Latino patients with type 2 diabetes mellitus.

RESEARCH DESIGN AND METHODS

Data from 745 patients who self-identified their ethnicity as Hispanic or Latino were pooled from six randomized, placebo-controlled phase 3 trials. Participants received linagliptin (5 mg/day) or placebo as monotherapy, or in combination with other oral antidiabetes drugs for 18 or 24 weeks.

RESULTS

The placebo-adjusted mean change (95% CI) in glycated hemoglobin from baseline (mean 8.2%) was -0.63% (-0.77 to -0.48; p<0.0001) at week 18, and -0.58% (-0.74 to -0.42; p<0.0001) at week 24. The placebo-adjusted mean change (95% CI) in fasting plasma glucose from baseline was -11.7 mg/dL (-19.3 to -4.0; p=0.0028) at week 18 and -14.1 mg/dL (-22.0 to -6.3; p=0.0004) at week 24. Hypoglycemia incidence was 17.4% with linagliptin and 21% with placebo. In patients not receiving concomitant sulfonylurea, the hypoglycemia incidence was 10.1% with linagliptin and 19.4% with placebo. The overall incidence of adverse events (AEs), drug-related AEs, and serious AEs with linagliptin was similar to placebo (AEs 67.6% vs 68.9%; drug-related AEs 15.1% vs 18.7%; serious AEs 3.6% vs 3.0%). The mean body weight remained unchanged in both groups.

CONCLUSIONS

In Hispanic/Latino patients with inadequately controlled type 2 diabetes mellitus, linagliptin provided clinically meaningful improvements in glycemic control without weight gain or increased risk of hypoglycemia.

Ethnic and gender susceptibility to metabolic risk

BACKGROUND

Aggregation of metabolic risk factors-i.e., elevated plasma triglyceride (TG), reduced high-density lipoprotein cholesterol (HDL-C), elevated blood pressure, and raised plasma glucose-convey increased risk for atherosclerotic cardiovascular disease and type 2 diabetes.

METHODS

This study was carried out to determine the association of waist girth, ethnicity, and gender with susceptibility for metabolic risk. Included were 1671 adult women (50.7% black) and 1339 men (46.5% black) enrolled in the Dallas Heart Study. Subjects were stratified into three categories by waist girth-low, intermediate, and high, corresponding to BMI ranges of <25 kg/m(2), 25-29.9 kg/m(2), and ≥30 kg/m(2).

RESULTS

Risk factor prevalence rose progressively through each waist-girth category. However, even among those with high waist-girth, prevalence of three or more risk factors was less than 50%. Several differences among the ethnic groups were noted; for example, Hispanic men had a higher prevalence of elevated TG compared to whites; black men, on the other hand, had a lower frequency of high TG. There were also fewer black men with low HDL-C than in the other groups. Black and Hispanic men had a higher prevalence of elevated glucose and updated homeostasis model assessment of insulin resistance (HOMA2-IR) than whites. More black men had elevated blood pressure than other groups. These differences were less pronounced among ethnic groups of women.

CONCLUSION

Although ethnic and gender differences in risk factor prevalence may exist, it is notable that the majority of subjects, even when obese, did not have elevated risk factors. This finding points to the need to focus largely on subjects with metabolic risk factors when implementing therapeutic interventions.

Race/ethnic difference in diabetes and diabetic complications

Health disparities in diabetes and its complications and comorbidities exist globally. A recent Endocrine Society Scientific Statement described the Health Disparities in several endocrine disorders, including type 2 diabetes. In this review, we summarize that statement and provide novel updates on race/ethnic differences in children and adults with type 1 diabetes, children with type 2 diabetes, and in Latino subpopulations. We also review race/ethnic differences in the epidemiology of diabetes, prediabetes, and diabetes complications and mortality in the United States and globally. Finally, we discuss biological, behavioral, social, environmental, and health system contributors to diabetes disparities to identify areas for future preventive interventions.

β-Cell dysfunction is associated with metabolic syndrome severity in adults

BACKGROUND

Metabolic syndrome is prevalent in adults characterized by increased visceral adiposity and insulin resistance (IR). However, the link between pancreatic β-cell function and metabolic syndrome severity in adults across the glucose spectrum is unknown. We hypothesized that poor β-cell function would independently predict a higher metabolic syndrome Z-score (i.e., severity).

METHODS

Seventy (12 normal glucose tolerant, 37 prediabetic, 21 type 2 diabetic) obese adults [62.4±1.1 year; 34.6±0.6 kg/m(2); data are mean±standard error of the mean (SEM)] participated in this cross-sectional study. A 2-hr 75-gram oral glucose tolerance test (OGTT) was administered, and insulin and glucose area under the curve was determined for calculations of insulin action. Fasting and glucose-stimulated insulin secretion was calculated using homeostasis model assessment of insulin secretion (HOMA-B) and the insulinogenic index (i.e., I(0-30)/Glc(0-30) or I(60-120)/Glc(60-120)), respectively. Fasting and postprandial insulin sensitivity was assessed by HOMA-IR and the Matsuda Index, respectively. β-cell function was estimated using the disposition index via HOMA-B/HOMA-IR, I(0-30)/Glc(0-30) or I(60-120)/Glc(60-120) × Matsuda Index, which represents basal, first-, and second-phase insulin release, respectively. Body composition (via computerized tomography and dual X-ray absorptiometry) and sex-specific metabolic syndrome Z-scores were calculated from waist circumference, blood pressure, fasting glucose, triglycerides, and high-density lipoproteins.

RESULTS

Compared to those with normal glucose tolerance, visceral fat and IR were higher and β-cell function was lower in adults with glucose intolerance and type 2 diabetes mellitus. Elevated visceral fat and IR (HOMA-IR and Matsuda Index) correlated with elevated Z-scores (r=0.51, r=0.54, r=-0.49; all P<0.002, respectively). Basal, first-, and second-phase β-cell function correlated with low Z-scores (r=-0.59, r=-0.51, and r=-0.43, all P<0.001). Insulin secretion significantly predicted the Z-score independent of sex, body fat, blood lipids, blood pressure, IR, and glucose metabolism (P<0.005).

CONCLUSION

β-cell dysfunction is highly correlated with the severity of metabolic syndrome in adults. Future work is warranted to elucidate the mechanism by which cardiometabolic disturbances influence insulin secretion.

Pharmacokinetic and pharmacodynamic evaluation of linagliptin in African American patients with type 2 diabetes mellitus

AIM

This was an open label, multicentre phase I trial to study the pharmacokinetics and pharmacodynamics of the dipeptidyl peptidase-4 (DPP-4) inhibitor linagliptin in African American patients with type 2 diabetes mellitus (T2DM).

METHODS

Forty-one African American patients with T2DM were included in this study. Patients were admitted to a study clinic and administered 5 mg linagliptin once daily for 7 days, followed by 7 days of outpatient evaluation.

RESULTS

Primary endpoints were area under the plasma concentration-time curve (AUC), maximum plasma concentration (Cmax ) and plasma DPP-4 trough inhibition at steady-state. Linagliptin geometric mean AUC was 194 nmol l(-1) h (geometric coefficient of variation, 26%), with a Cmax of 16.4 nmol l(-1) (41%). Urinary excretion was low (0.5% and 4.4% of the dose excreted over 24 h, days 1 and 7). The geometric mean DPP-4 inhibition at steady-state was 84.2% at trough and 91.9% at maximum. The exposure range and overall pharmacokinetic/pharmacodynamic profile of linagliptin in this study of African Americans with T2DM was comparable with that in other populations. Laboratory data, vital signs and physical examinations did not show any relevant findings. No safety concerns were identified.

CONCLUSIONS

The results of this study in African American patients with T2DM support the use of the standard 5 mg dose recommended in all populations.

Use of the estimated glucose disposal rate as a measure of insulin resistance in an urban multiethnic population with type 1 diabetes

OBJECTIVE

Insulin resistance has been described in type 1 diabetes mellitus, is related to risk of vascular complications, and may be more common in certain ethnic groups. Estimated glucose disposal rate (eGDR) is a validated clinical tool for estimating insulin sensitivity in type 1 diabetes. Because previous reports of eGDR in adults with type 1 diabetes have included few ethnic minorities, this study explored interethnic differences in eGDR and the relationship of eGDR with diabetic vascular complications.

RESEARCH DESIGN AND METHODS

We conducted a cross-sectional study using a sample that included 207 white, black, or Hispanic adults with prior clinical diagnosis of type 1 diabetes who were receiving care at an urban academic medical center. eGDR (milligrams per kilogram per minute) was calculated using HbA1c, waist circumference, and hypertensive status. Race/ethnicity was self-reported. Multivariable logistic regression models were used to estimate odds ratios (ORs) and 95% CIs of association of eGDR with diabetes complications (cardiovascular disease, retinopathy, albuminuria, and chronic kidney disease above stage 3).

RESULTS

Forty-two percent of the participants were women, and mean age was 45 ± 15 years; 34% were white, 32% were Hispanic, and 34% were black. Ethnicity was significantly associated with eGDR; blacks had significantly lower eGDR (5.66 ± 2.34) than Hispanics (6.70 ± 2.29) and whites (7.20 ± 2.03) (P < 0.001). Patients with the lowest eGDR compared with the highest had a significantly greater risk of any diabetes complication (OR 3.1 [95% CI 1.2-8.1]) compared with the least insulin-resistant patients.

CONCLUSIONS

In an urban clinic population of patients with type 1 diabetes, blacks were significantly less insulin sensitive than whites or Hispanics, and lower eGDR was associated with diabetes complications. Further study is needed to determine whether using eGDR to target interventions can improve outcomes.

Ethnic differences in beta-cell function, dietary intake and expression of the metabolic syndrome among UK adults of South Asian, black African-Caribbean and white-European origin at high risk of metabolic syndrome

A cross-sectional analysis of ethnic differences in dietary intake, insulin sensitivity and beta-cell function, using the intravenous glucose tolerance test (IVGTT), was conducted on 497 healthy adult participants of the 'Reading, Imperial, Surrey, Cambridge, and Kings' (RISCK) study. Insulin sensitivity (Si) was significantly lower in African-Caribbean (AC) and South Asian (SA) participants [IVGTT-Si; AC: 2.13 vs SA: 2.25 vs white-European (WE): 2.84 (×10(-4) mL µU min)(2), p < 0.001]. AC participants had a higher prevalence of anti-hypertensive therapy (AC: 19.7% vs SA: 7.5%), the most cardioprotective lipid profile [total:high-density lipoprotein (HDL); AC: 3.52 vs SA: 4.08 vs WE: 3.83, p = 0.03] and more pronounced hyperinsulinaemia [IVGTT-acute insulin response (AIR)] [AC: 575 vs SA: 428 vs WE: 344 mL/µU/min)(2), p = 0.002], specifically in female participants. Intake of saturated fat and carbohydrate was lower and higher in AC (10.9% and 50.4%) and SA (11.1% and 52.3%), respectively, compared to WE (13.6% and 43.8%, p < 0.001). Insulin resistance in ACs is characterised by 'normal' lipid profiles but high rates of hypertension and pronounced hyperinsulinaemia.

Non-alcoholic fatty liver disease as an independent manifestation of the metabolic syndrome: results of a US national survey in three ethnic groups

BACKGROUND AND AIM

The metabolic syndrome (MetS) and each of its components are strongly associated with non-alcoholic fatty liver disease (NAFLD). This has led many investigators to suggest that NAFLD is an independent component of the MetS. We formally tested this hypothesis using confirmatory factor analysis, which allows comparison of different models, with or without including NAFLD as a component of the MetS.

METHODS

We analyzed data from 3846 subjects of the Third National Health and Nutrition Examination Survey (1988-1994). NAFLD was defined by increased liver fat measured by ultrasonography.

RESULTS

MetS by Adult Treatment Panel III criteria was present in 20.5%, and 30.2% had NAFLD, defined as mild, moderate, or severe ultrasonographic steatosis. Using confirmatory factor analysis, a basic model representing the MetS using its currently accepted components (glucose, waist, triglyceride/high-density lipoprotein ratio, and mean arterial pressure) showed excellent goodness-of-fit statistics. Addition of NAFLD to the model as a fifth independent variable decreased model fit, suggesting that NAFLD is not an additional independent component of the MetS. Analysis by ethnicity showed that addition of NAFLD decreased model fit in Whites but resulted in minor improvements in non-Hispanic Blacks and Mexican Americans.

CONCLUSIONS

The MetS is strongly associated with NAFLD. However, we found no evidence that NAFLD is an independent component or manifestation of the MetS. Interestingly, ethnic differences might be important in this relationship and require further study.