Renin-Angiotensin-Aldosterone System, Glucose Metabolism and Incident Type 2 Diabetes Mellitus: MESA.

Background Mechanistic studies suggest that aldosterone impairs glucose metabolism. We investigated the cross-sectional associations of aldosterone and plasma renin activity with fasting plasma glucose, insulin resistance ( IR ), β-cell function, and longitudinal association with incident diabetes mellitus among adults in MESA (the multiethnic study of atherosclerosis) prospective cohort study. Methods and Results Homeostatic model assessment of IR ( HOMA 2- IR ) and HOMA 2-β were used to estimate IR and β-cell function, respectively. Incident diabetes mellitus was defined as fasting plasma glucose ≥126 mg/dL or anti-diabetic medication use at follow-up. Linear regression was used to examine cross-sectional associations of aldosterone with fasting plasma glucose, HOMA 2- IR and HOMA 2-β; Cox regression was used to estimate hazard ratios ( HR ) for incident diabetes mellitus with multivariable adjustment. There were 116 cases of incident diabetes mellitus over 10.5 years among 1570 adults (44% non-Hispanic white, 13% Chinese American, 19% Black, 24% Hispanic American, mean age 64±10 years, 51% female). A 100% increase in log-aldosterone was associated with a 2.6 mg/dL higher fasting plasma glucose, 15% higher HOMA 2- IR and 6% higher HOMA 2-β ( P<0.01). A 1- SD increase in log-aldosterone was associated with a 44% higher risk of incident diabetes mellitus ( P<0.01) with the greatest increase of 142% ( P<0.01) observed in Chinese Americans ( P for interaction=0.09 versus other ethnicities). Similar cross-sectional findings for log-plasma renin activity existed, but log-plasma renin activity was not associated with incident diabetes mellitus after full adjustment. Conclusions Aldosterone is associated with glucose homeostasis and diabetes mellitus risk with graded associations among Chinese Americans and blacks, suggesting that pleiotropic effects of aldosterone may represent a modifiable mechanism in diabetes mellitus pathogenesis with potential racial/ethnic variation

Acculturation is associated with left ventricular mass in a multiethnic sample: the Multi-Ethnic Study of Atherosclerosis.

BackgroundAcculturation involves stress-related processes and health behavioral changes, which may have an effect on left ventricular (LV) mass, a risk factor for cardiovascular disease (CVD). We examined the relationship between acculturation and LV mass in a multiethnic cohort of White, African-American, Hispanic and Chinese subjects.MethodsCardiac magnetic resonance assessment was available for 5004 men and women, free of clinical CVD at baseline. Left ventricular mass index was evaluated as LV mass indexed by body surface area. Acculturation was characterized based on language spoken at home, place of birth and length of stay in the United States (U.S.), and a summary acculturation score ranging from 0 = least acculturated to 5 = most acculturated. Mean LV mass index adjusted for traditional CVD risk factors was compared across acculturation levels.ResultsUnadjusted mean LV mass index was 78.0 ± 16.3 g/m(2). In adjusted analyses, speaking exclusively English at home compared to non-English language was associated with higher LV mass index (81.3 ± 0.4 g/m(2) vs 79.9 ± 0.5 g/m(2), p = 0.02). Among foreign-born participants, having lived in the U.S. for ≥ 20 years compared to < 10 years was associated with greater LV mass index (81.6 ± 0.7 g/m(2) vs 79.5 ± 1.1 g/m(2), p = 0.02). Compared to those with the lowest acculturation score, those with the highest score had greater LV mass index (78.9 ± 1.1 g/m(2) vs 81.1 ± 0.4 g/m(2), p = 0.002). There was heterogeneity in which measure of acculturation was associated with LV mass index across ethnic groups.ConclusionsGreater acculturation is associated with increased LV mass index in this multiethnic cohort. Acculturation may involve stress-related processes as well as behavioral changes with a negative effect on cardiovascular health

The American Heart Association Ideal Cardiovascular Health and Incident Type 2 Diabetes Mellitus Among Blacks: The Jackson Heart Study

Background: The concept of ideal cardiovascular health (CVH), defined by the American Heart Association primarily for coronary heart disease and stroke prevention, may apply to diabetes mellitus prevention among blacks. Methods and Results: Our sample included 2668 adults in the Jackson Heart Study with complete baseline data on 6 of 7 American Heart Association CVH metrics (body mass index, healthy diet, smoking, total cholesterol, blood pressure, and physical activity). Incident diabetes mellitus was defined as fasting glucose ≥126 mg/dL, physician diagnosis, use of diabetes mellitus drugs, or glycosylated hemoglobin ≥6.5%. A summary CVH score from 0 to 6, based on presence/absence of ideal CVH metrics, was derived for each participant. Cox regression was used to estimate adjusted hazard ratios. Mean age was 55 years (65% women) with 492 incident diabetes mellitus events over 7.6 years (24.6 cases/1000 person‐years). Three quarters of participants had only 1 or 2 ideal CVH metrics; no participant had all 6. After adjustment for demographic factors (age, sex, education, and income) and high‐sensitivity C‐reactive protein, each additional ideal CVH metric was associated with a 17% diabetes mellitus risk reduction (hazard ratio, 0.83; 95% CI, 0.74–0.93). The association was attenuated with further adjustment for homeostasis model assessment for insulin resistance (hazard ratio, 0.89; 95% CI, 0.79–1.00). Compared with participants with 1 or no ideal CVH metric, diabetes mellitus risk was 15% and 37% lower in those with 2 and ≥3 ideal CVH metrics, respectively. Conclusions: The AHA concept of ideal CVH is applicable to diabetes mellitus prevention among blacks. These associations were largely explained by insulin resistance

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+/-3.2mg/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