Alcohol consumption and the incidence of type 2 diabetes: a 20-year follow-up of the Finnish twin cohort study

Abstract

Objective: The aim of this study was to investigate alcohol consumption in relation to the incidence of type 2 diabetes.

Research design and methods: The study population consisted of 22778 twins of the Finnish Twin Cohort. This cohort was compiled in 1975 and includes all same-sexed twins born in Finland before 1958. Information on alcohol, smoking, diet, physical activity, medical, and social conditions was obtained by questionnaires administered in 1975, 1981, and 1990. By record linkage to national registers of hospital discharge and prescribed medication, 580 incident cases of type 2 diabetes were identified during 20 years of follow-up.

Results: Moderate alcohol consumption (5-29.9 g/day in men and 5-19.9 g/day in women) tended to be associated with a reduced incidence of type 2 diabetes compared with low consumption (<5 g/day). The estimates were lower in overweight (BMI >or=25.0 kg/m(2)) subjects (relative risk 0.7, 95% CI 0.5-1.0 [men]; 0.6, 0.3-1.1 [women]). High alcohol consumption (>or=20 g/day) was associated with an increased incidence of type 2 diabetes in lean women (2.9, 1.1-7.5) but not in overweight women or in men. In women, binge drinking was associated with an increased incidence of type 2 diabetes (2.1, 1.0-4.4). Analyses of alcohol-discordant twin pairs supported a reduced risk in moderate consuming twins compared with their low-consuming cotwins (odds ratio 0.5, 95% CI 0.2-1.5).

Conclusions: The results of this study suggested that moderate alcohol consumption may reduce the risk of type 2 diabetes. On the other hand, binge drinking and high alcohol consumption may increase the risk of type 2 diabetes in women.