Acute alcohol consumption improves insulin action without affecting insulin secretion in type 2 diabetic subjects

Long-term exposure to alcohol is associated with an improvement in insulin sensitivity. At this time, however, there is no definitive proof that alcohol per se has an effect on the insulin sensitivity index (S(i)) in type 2 diabetes patients. The aim of the present study was to assess the role of acute moderate alcohol intake on insulin sensitivity and insulin secretion in comparable subjects with and without type 2 diabetes.

Frequently sampled intravenous glucose tolerance tests (FSIGTs) were performed twice on eight healthy and eight type 2 diabetic volunteers. Forty grams of alcohol (vodka 40% wt/vol) or tap water were sipped from time -60 min to the end of the FSIGT.

Lactate area under the curve (AUC) was higher in both groups during the alcohol study than in the control study. Free fatty acid (FFA) AUC was higher in type 2 diabetic subjects than in control subjects; alcohol slightly reduced FFA by 17% in control subjects (34 +/- 4 mmol. min(-1). l(-1); P = 0.1) but significantly decreased FFA by 23% in type 2 diabetic subjects (54 +/- 10; P = 0.007). Beta-cell response was markedly reduced in type 2 diabetic subjects regardless of the type of study. Alcohol significantly increased S(i) in both groups.

Acute alcohol consumption improves insulin action without affecting beta-cell secretion. This effect may be partly due to the inhibitory effect of alcohol on lipolysis. Alcohol intake increases insulin sensitivity and may partly explain both the J-shaped relationship between the prevalence of diabetes and the amount of alcohol consumption and the decreased mortality for myocardial infarction.