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 >= 40 g per day, >= 20 cigarettes per day further increased GGT levels. Alcohol consumption showed a U-shaped association with HOMA-IR. In contrast, smoking 20-39 and >= 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.