Short- and medium-term effects of light to moderate alcohol intake on glycaemic control in diabetes mellitus: a systematic review and meta-analysis of randomized trials.

BACKGROUND: People with diabetes are told that drinking alcohol may increase their risk of hypoglycaemia. AIMS: To report the effects of alcohol consumption on glycaemic control in people with diabetes mellitus. METHODS: Medline, EMBASE and the Cochrane Library databases were searched in 2015 to identify randomized trials that compared alcohol consumption with no alcohol use, reporting glycaemic control in people with diabetes. Data on blood glucose, HbA1c and numbers of hypoglycaemic episodes were pooled using random effects meta-analysis. RESULTS: Pooled data from nine short-term studies showed no difference in blood glucose concentrations between those who drank alcohol in doses of 16-80 g (median 20 g, 2.5 units) compared with those who did not drink alcohol at 0.5, 2, 4 and 24 h after alcohol consumption. Pooled data from five medium-term studies showed that there was no difference in blood glucose or HbA1c concentrations at the end of the study between those who drank 11-18 g alcohol/day (median 13 g/day, 1.5 units/day) for 4-104 weeks and those who did not. We found no evidence of a difference in number of hypoglycaemic episodes or in withdrawal rates between randomized groups. CONCLUSIONS: Studies to date have not provided evidence that drinking light to moderate amounts of alcohol, with or without a meal, affects any measure of glycaemic control in people with Type 2 diabetes. These results suggest that current advice that people with diabetes do not need to refrain from drinking moderate quantities of alcohol does not need to be changed; risks to those with Type 1 diabetes remain uncertain.