Association between gamma-glutamyltransferase levels and insulin resistance according to alcohol consumption and number of cigarettes smoked.

AIM: Alcohol intake may increase serum gamma-glutamyltransferase (GGT) but reduce insulin resistance. We analyzed the association between GGT and a marker of insulin resistance, homeostasis model assessment for insulin resistance (HOMA-IR), according to the drinking and smoking status. METHODS: After excluding former smokers and/or former drinkers, the data of 10,482 men who underwent general health screening were analyzed. RESULTS: Alcohol consumption showed a graded association with GGT. In men with current alcohol consumption of > or =40 g per day, > or =20 cigarettes per day further increased GGT levels. Alcohol consumption showed a U-shaped association with HOMA-IR. In contrast, smoking 20-39 and > or =40 cigarettes per day increased HOMA-IR as compared with never smokers. An interaction between alcohol consumption and smoking was present for GGT (p<0.001) and HOMA-IR (p=0.059). GGT was not a significant negative predictive value for HOMA-IR regardless of the drinking or smoking status. CONCLUSIONS: Although alcohol intake showed a graded association with GGT and a U-shaped association with HOMA-IR, serum GGT can be utilized as a predictor of insulin resistance in current drinkers.