Alcohol consumption and risk of type 2 diabetes mellitus in Japanese: a systematic review.

OBJECTIVE: To evaluate the association between alcohol consumption and the risk for type 2 diabetes (DM) in Japanese. METHODS: We searched the MEDLINE data base with the key words 'alcohol intake' (or 'alcohol consumption') and 'Japanese' cross-linked with 'diabetes mellitus' (or 'impaired glucose tolerance'). The reports we sought were restricted to prospective cohort studies, randomized controlled trials, meta-analyses and systematic reviews. Computerized and hand searches were conducted in June 2007. RESULTS: Seven prospective cohort studies were adopted. We previously reported that in lean Japanese men (BMI < or =22.0 kg/m2), moderate to heavy alcohol intake is a risk factor for diabetes. One study found heavy alcohol intake to be associated with an increased risk in low-BMI men while moderate alcohol intake was associated with a reduced risk in higher-BMI men. Another study suggested daily alcohol consumption to be a risk factor in low-BMI participants, while being protective in middle-BMI participants. Yet another study demonstrated a U-shaped association between alcohol consumption and the risk of diabetes in men. Three other studies, which did not divide the subjects in terms of BMI values, indicated alcohol intake to be an increased risk for diabetes, two being in men and one being in women, respectively. CONCLUSION: For a large number of Japanese men who have relatively low BMI, alcohol intake is an established risk factor for diabetes. [ABSTRACT FROM AUTHOR]