Alcohol consumption and diabetes risk in the Diabetes Prevention Program

Abstract

Background: 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.

Objectives: 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).

Design: DPP participants (n = 3175) had impaired glucose tolerance (2-h glucose: 7.8-11.1 mmol/L), elevated fasting glucose (5.3-7.0 mmol/L), and a body mass index (in kg/m(2)) > or =24. Participants were randomly assigned to placebo, metformin, or lifestyle modification and were followed for a mean of 3.2 y. Alcohol intake was assessed at baseline and year 1 by using a semiquantitative food-frequency questionnaire. Diabetes was diagnosed by annual oral-glucose-tolerance testing and semiannual fasting plasma glucose measurement.

Results: Participants who reported higher alcohol consumption tended to be male, older, white, and less obese and to have a higher calorie intake and a higher HDL-cholesterol concentration. Higher alcohol consumption was associated with lower insulin secretion at any level of insulin sensitivity. We found lower incidence rates of diabetes with higher alcohol consumption in the metformin (P < 0.01 for trend) and lifestyle modification (P = 0.02 for trend) groups, which remained significant after adjustment for multiple baseline covariates. No similar association was observed in the placebo group.

Conclusions: 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. Moderate daily alcohol intake is associated with lower insulin secretion-an effect that warrants further investigation. This trial was registered at clinicaltrials.gov as NCT00038727.

Figures

FIGURE 1

Relation of insulin secretion (corrected insulin response at 30 min; CIR30) to insulin sensitivity [1/homeostasis model assessment of insulin resistance (HOMA-IR)] by baseline alcohol intake. Curves were derived from linear regression models between log-transformed insulin secretion (CIR30) and log-transformed insulin sensitivity (1/HOMA-IR) in each alcohol consumption category and were plotted as untransformed (re-exponentiated) curves. P < 0.001 for differences across alcohol consumption categories after adjustment for age and sex. P = 0.019 after adjustment for age, sex, race-ethnicity, BMI, exercise (metabolic equivalent task-hours/wk), and calorie intake (P = 0.049 excluding current smokers).

FIGURE 2

Unadjusted diabetes incidence rates by alcohol consumption category and treatment arm in the Diabetes Prevention Program. Vertical lines represent 1 SE. P values represent the unadjusted trend in diabetes incidence across alcohol consumption categories.