Insulin sensitivity and regular alcohol consumption: large, prospective, cross sectional population study (Bruneck study).

Objectives: To assess the relation between regular alcohol consumption and insulin sensitivity, and to estimate the importance of insulin in the association of alcohol with multiple vascular risk factors and cardiovascular disease.

Design: Prospective and cross sectional study of a large randomly selected population sample.

Setting: Part of the Bruneck study 1990-5 (Bolzano province, Italy).

Subjects: 820 health, non-diabetic women and men aged 40-79 years.

Main Outcome Measure: Concentrations of fasting and post-glucose insulin, cholesterol, apolipoproteins, triglycerides, Lp(a) lipoprotein glucose, fibrinogen, and antithrombin III; blood pressure; insulin resistance estimated by the homeostasis model assessment.

Results: Fasting insulin concentrations in those who did not drink alcohol and subjects reporting low (1-50 g/day), moderate (51-99 g/day), and heavy (> or = 100 g/day) alcohol intake were 12.4, 10.0, 8.7, and 7.1 mU/l (P < 0.001). Likewise, post-glucose insulin concentrations and estimates for insulin resistance assessed by the homeostasis model assessment decreased significantly with increasing amounts of regular alcohol consumption. These trends were independent of sex, body mass index, physical activity, cigarette smoking, medication, and diet (P < 0.001). Regular alcohol intake predicted multiple changes in vascular risk factors over a five year period including increased concentrations of high density lipoprotein cholesterol and apolipoprotein A I; higher blood pressure; and decreased concentration of antithrombin III. These associations were in part attributable to the decrease in insulin concentrations observed among alcohol consumers.

Conclusions: Low to moderate amounts of alcohol, when taken on a regular basis, improve insulin sensitivity. Insulin is a potential intermediate component in the association between alcohol consumption and vascular risk factors (metabolic syndrome).