Alcohol Acutely Increases Vascular Reactivity together with Insulin Sensitivity in Type 2 Diabetic Men

Moderate alcohol consumption is associated with increased insulin sensitivity and reduced cardiovascular risk. We hypothesized that this relates to a direct effect of alcohol and therefore investigated whether acute alcohol intake altered insulin sensitivity or endothelial function in patients with type 2 diabetes. In an open-label two period design, the effect of a single oral dose of 40 g of alcohol (168 ml 40% vodka) on an insulin-modified frequently sampled intravenous glucose tolerance test (FSIGT) and on endothelium-dependent (flow mediated, FMD) or endothelium-independent (glyceroltrinitrate (GTN)-induced) vasodilation of the brachial artery measured by ultrasound was studied. Experiments were carried out in twelve male patients with type 2 diabetes mellitus (64 +/- 6 years, body mass index 28.4 +/- 5.7 kg/m(2)). Baseline insulin sensitivity index (S-I) was 1.10 +/- 0.3 4 min(-1).mu U-1.ml, baseline FMD was +4.1 +/- 3.0%, and GTN-induced vasodilation +7.4 +/- 2.3% from resting brachial artery diameter. Acute alcohol intake increased alcohol plasma levels to 0.33 +/- 0.04 parts per thousand, S-I to 1.86 +/- 0.45 min(-1).mu U-1.ml (p<0.05), and FMD to +8.2 +/- 2.8% (p<0.05), while GTN-induced dilation remained unchanged. No relationship was detectable between the observed changes. We conclude that alcohol intake acutely increases endothelium-dependent brachial artery vasodilation in patients with type 2 diabetes together with insulin sensitivity. This acute effect might explain some beneficial effects of low alcohol consumption in epidemiological observations.