Recommendations for moderate alcohol consumption remain controversial, particularly in type 2 diabetes mellitus, so Israel researchers designed a two-year randomized control trial to assess the cardiometabolic effects of initiating moderate alcohol intake in patients with type 2 diabetes and whether the type of wine matters (Annal Int Med. 2015;163(8):569-79).
Alcohol-abstaining adults with well-controlled type 2 diabetes were randomly assigned to 150 mL of mineral water, white wine or red wine with dinner for two years. The wines and mineral water were provided, and all groups followed a Mediterranean diet without caloric restriction.
Of the 224 patients who were randomly assigned, 94 percent had follow-up data at one year and 87 percent at two years. In addition to the changes in the water group (Mediterranean diet only), red wine significantly increased high-density lipoprotein cholesterol (HDL) level by 0.05 mmol/L and apolipoprotein level (which are used to evaluate cardiovascular disease risk) by 0.03 g/L and decreased the total cholesterol : HDL ratio by 0.27. Only slow ethanol metabolizers significantly benefited from the effect of both wines on glycemic control compared with fast ethanol metabolizers. Across the three groups, no material differences were identified in blood pressure, adiposity, liver function, drug therapy, symptoms or quality of life, except that sleep quality improved in both wine groups compared with the water group. Overall, compared with the changes in the water group, red wine further reduced the number of components of the metabolic syndrome by 0.34.
This long-term randomized clinical trial suggests initiating moderate wine intake, especially red wine, among well-controlled diabetics as part of a healthy diet is apparently safe and modestly decreases cardiometabolic risk. The genetic interactions suggest that ethanol plays an important role in glucose metabolism, and red wine's effects also involve nonalcoholic constituents.
**A limitation the researchers noted was the participants were not blinded to treatment allocation.