Correlation between insulin resistance and γ-glutamyl transpeptidase sensitivity in light drinkers

Background: Our previous studies suggested that serum γ-glutamyl transpeptidase (GGTP) level was correlated with insulin resistance level estimated by the homeostasis model assessment in teetotalers and occasional drinkers. In the surveys, strong correlation between GGTP and triglyceride also was observed. This study examined whether the correlation held true for regular drinkers. Methods: Seven hundred and seventeen male subjects in annual health checkups were divided into three groups according to their drinking styles and further divided into four subgroups according to their serum GGTP levels. In the other surveys, they were ranked by their amount of ethanol consumption. The correlation between GGTP and insulin resistance level was studied in each group. Results: Single regression analysis and analysis of variance showed that GGTP level was significantly correlated with insulin resistance level as determined by the homeostasis model assessment, as well as with triglyceride level regardless of subjects' drinking styles. The associations were confirmed by multiple regression analyses in which age, levels of uric acid, total cholesterol, high-density lipoprotein cholesterol, and body mass index were adjusted, at least in nondrinkers or light drinkers. However, the multiple regression analyses indicated that the association between GGTP and insulin resistance level was not significant in subjects who take ethanol more than five times per week. The studies according to the amount of subjects' ethanol consumption indicated that the association between GGTP and insulin resistance was significant in the subjects who take ethanol up to 280 g/week. Conclusion: Individual variation in insulin resistance status may contribute to individual variations of sensitivity of GGTP to ethanol intake, at least in light drinkers.