BACKGROUND: There is a great deal of controversy surrounding the relationship 
between alcohol consumption and insulin resistance. This association may be 
further confounded by the presence of obesity. We aimed to clarify whether 
regular alcohol consumption improves insulin resistance in healthy Japanese men 
and whether obesity affects this relationship.
METHODS: We examined 1029 men (ages 24 to 87 y) who had undergone medical 
checkups. They were divided into non-obese (body mass index (BMI) <25 kg/m(2)) 
or obese subjects (BMI > or =25 kg/m(2)) and further classified into non-regular 
drinkers (NRD), moderate drinkers (MD; 1-6 days/week), and daily drinkers (DD; 7 
days/week). The homeostasis model assessment of insulin resistance (HOMA-IR) and 
other cardiac risk factors were compared between the groups.
RESULTS: In both non-obese and obese men, alcohol consumption decreased HOMA-IR 
in a dose-dependent manner, although HOMA-IR was about 2 times greater in obese 
men compared to non-obese men in any category (p<0.001). Stepwise logistic 
regression analysis revealed that alcohol consumption was the independent 
negative risk factor for HOMA-IR [OR, 0.576 (95% C.I. 0.402-0.824), p=0.003] 
after adjusting for age, BMI, systolic blood pressure, smoking status, 
LDL-cholesterol, HDL-cholesterol, and liver dysfunction.
CONCLUSIONS: Regular alcohol consumption improves insulin resistance in healthy 
Japanese men independent of obesity.