Associations between alcohol consumption and insulin sensitivity and cardiovascular disease risk factors: the Insulin Resistance and Atherosclerosis Study.

OBJECTIVE: Light-to-moderate alcohol consumption has been associated with reduced cardiovascular disease (CVD) mortality, which may be explained by increased insulin sensitivity (SI) and an improved lipoprotein and blood pressure profile. Prior research has shown improved SI with light-to-moderate alcohol intake even though somewhat imprecise measures of SI were used. RESEARCH DESIGN AND METHODS: Relationships between alcohol use and SI and CVD risk factors were assessed in a cross-sectional analysis of 1,196 white, African-American, and Hispanic men and women from the Insulin Resistance and Atherosclerosis Study (IRAS). Five categories of previous-year alcohol use (never, <0.5 drinks/day, 0.5-0.99 drinks/day, 1-2.99 drinks/day, and > or =3 drinks/day) and log SI + 1 (frequently sampled intravenous glucose tolerance test with Bergman minimal model analysis), log fasting insulin, log triglycerides, HDL cholesterol, and systolic/diastolic blood pressure were examined using analysis of variance. RESULTS: Univariate analysis showed an inverse U-shaped relationship between SI and alcohol intake, with a peak at the 0.5-0.99 drinks/day category. A U-shaped relationship was observed between fasting insulin and the lipid and blood pressure measures. After adjustment for demographic (clinic, sex, ethnicity, age), lifestyle (smoking, dietary energy/fat intake, physical activity), and physical (BMI, waist circumference) variables, the alcohol/insulin association was attenuated, but the association with lipids and blood pressure remained for high-intake categories. CONCLUSIONS: These data suggest that the enhanced SI associated with light-to-moderate alcohol consumption may be a function solely of a BMI and central adiposity profile more favorable to higher SI.