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 40g of alcohol (168ml 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±5.7kg/m 2). Baseline insulin sensitivity index (SI) was 1.10±0.34min-1.μU-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‰, SI to 1.86±0.45min -1.μU-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 ar-tery 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.