Alcohol Linked to Lower Risk for Diabetes and Less Insulin Secretion

Moderate daily alcohol intake (1-3 drinks per day) is linked to a reduced risk for incident diabetes and to lower insulin secretion in patients assigned to metformin or lifestyle modification for diabetes prevention, according to the results of a new study.

Jill P. Crandall, MD, (Albert Einstein College of Medicine, New York, which is participating in the Diabetes Prevention Program Research Group) writes, “Moderate alcohol consumption is associated with a decreased risk of Type 2 diabetes in the general population, but little is known about the effects in individuals at high risk of diabetes…. The objectives were to determine associations between alcohol consumption and diabetes risk factors and whether alcohol consumption was a predictor of incident diabetes in individuals enrolled in the Diabetes Prevention Program (DPP).”

The study cohort in the Diabetes Prevention Program consisted of 3,175 participants with impaired glucose tolerance (2-hour glucose: 140- 199mg/dL.[7.8 – 11.1 mmol/L]), elevated fasting glucose (95-126mg/dL. [5.3 – 7.0 mmol/L]), and a body mass index of 24 kg/m² or greater. Participants were randomly assigned to receive placebo, metformin, or lifestyle modification. With use of a semiquantitative food-frequency questionnaire, alcohol intake was evaluated at baseline and at 1 year. During follow-up (mean duration, 3.2 years), incident diabetes was diagnosed by annual oral-glucose-tolerance testing and semiannual fasting plasma glucose measurement.

Self-reported alcohol consumption tended to be higher in participants who were men, older, white, and less obese, with higher energy intake and a higher high-density lipoprotein cholesterol concentration. At any level of insulin sensitivity, higher consumption of alcohol was associated with lower insulin secretion. In the metformin and lifestyle modification groups, higher alcohol consumption was associated with lower incidence rates of diabetes (P < .01 and P = .02 for trend, respectively). These associations remained significant after adjustment for multiple baseline covariates but were not observed in the placebo group.

“Despite overall low rates of alcohol consumption, there was a reduced risk of incident diabetes in those who reported modest daily alcohol intake and were assigned to metformin or lifestyle modification,” the study authors write. “Moderate daily alcohol intake is associated with lower insulin secretion — an effect that warrants further investigation.”

Limitations of this study include baseline differences in diabetes risk factors among the alcohol consumption categories, possible unmeasured confounders, reliance on self-report to assess alcohol consumption, overall low alcohol consumption, and limited generalizability.

“The potential benefits of alcohol use in preventing diabetes may be limited to those who are actively pursuing other therapies to reduce risk,” the study authors conclude. “Moderate alcohol intake was associated with decreased insulin secretion, independent of insulin sensitivity. The effect of chronic alcohol consumption on glucose metabolism, especially b cell function, warrants further investigation.”

Am J Clin Nutr. Oct. 2009;90:595-601. Abstract