Relation of Gamma-glutamyltransferase and alcohol drinking with incident diabetes: the HIPOP-OHP study.

AIM Gamma-glutamyltransferase (GGT) is known to correlate well with alcohol consumption; however, the relation between GGT and diabetes and that between alcohol consumption and diabetes mellitus (DM) is inconsistent. Thus, several questions, such as whether light to moderate drinkers can be considered as low risk for diabetes incidence irrespective of their GGT level, is unresolved. In this study, we investigated the relation of GGT or alcohol drinking with DM incidence considering the body mass index (BMI) in healthy Japanese workers. METHODS We followed 3095 men who did not have DM at baseline for 4 years. Incident diabetes was defined as a fasting (non-fasting) plasma glucose level of >or=7.0 (11.1) mmol/L, or treatment of diabetes. Multiple adjusted hazard ratios (HR) were calculated using Cox proportional models. RESULTS Participants with higher GGT (GGT >or=27 IU/L) showed an increased risk of diabetes incidence even when their BMI level was low. Although a U-shaped relation between alcohol drinking and incident diabetes was observed, the risk to light to moderate drinkers (alcohol <23 g/day) was not low if they were either overweight (BMI >or=25 kg/m(2)) or had higher GGT (HR=2.60, p=0.08) or both overweight and higher GGT (HR=3.16, p=0.07) compared with never drinkers without higher GGT and overweight. CONCLUSIONS Higher GGT was associated with a higher incidence of DM irrespective of drinking status or obesity. Although a U-shaped relation between alcohol drinking and incident diabetes was observed, the risk to light to moderate drinkers was not low if they were either overweight or had higher GGT.