Light-to-moderate alcohol drinking reduces the impact of obesity on the risk of diabetes mellitus

Objective: Light-to-moderate alcohol drinking has been shown to reduce the risk of type 2 diabetes, for which obesity is a primary risk factor. The aim of this study was to determine whether drinking alcohol influences the relationship between obesity and hyperglycemia.Method: The relationships of adiposity indices with hyperglycemia were compared among middle-aged Japanese men (N = 12,627) who were non-, light-to-moderate (<22 g ethanol/day), heavy (≥22 and <44 g ethanol/day), and very heavy (≥44 g ethanol/day) drinkers. Results: There were significant positive correlations of hemoglobin A1c with body mass index (BMI) and waist-to-height ratio (WHtR), which were significantly weaker in light-to-moderate and heavy drinkers than in nondrinkers but were not significantly different in very heavy drinkers compared with nondrinkers. Odds ratios (ORs) for hyperglycemia in subjects with versus those without high BMI or WHtR were significantly higher than reference level of 1.00 in all the drinker groups and significantly lower in light-to-moderate and heavy drinkers compared with nondrinkers; however they were not significantly different in very heavy drinkers compared with nondrinkers. ORs of the interaction term consisting of alcohol drinking and high adiposity index were significantly lower than the reference level in the light-to-moderate and heavy drinkers (OR with 95% confidence interval: high BMI, 0.61 [0.41, 0.91] in light-to-moderate drinkers and 0.64 [0.48, 0.85] in heavy drinkers; high WHtR, 0.57 [0.38, 0.85] in light-to-moderate drinkers and 0.66 [0.50, 0.88] in heavy drinkers) but were not significantly different from the reference level in very heavy drinkers (high BMI, 0.90 [0.65, 1.25]; high WHtR, 1.04 [0.74, 1.46]). Conclusions: The associations between obesity and hyperglycemia were weaker in light-to-moderate drinkers than in nondrinkers. Thus, light-to-moderate drinking may reduce the impact of obesity on the risk for diabetes.