A Longitudinal Increase in Serum Gamma-Glutamyl Transferase Levels, but Not in Alanine Aminotransferase Levels, Improves the Prediction of Risk of Impaired Fasting Glucose in Male.

Abstract

Background: Impaired fasting glucose (IFG), being a pre-diabetic condition, can increase the risk of overt diabetes; thus early detection and prediction of IFG are important to reduce the incidence of overt diabetes. Some predictive factors, including serum alanine aminotransferase (ALT) and gamma-glutamyl transferase (GGT), have been reported in several studies, but none of the studies have investigated the effect of longitudinal changes in individual serum ALT and GGT levels on the risk of IFG.

Methods: We aimed to investigate the association between changes in the serum ALT and GGT levels and the risk of IFG using a checkup database between 1999 and 2014.

Results: A total of 3,598 males and 3,275 females were enrolled in the study. We performed a follow-up test of serum ALT or GGT in each individual, and classified the cases in which the serum ALT or GGT level was increased or decreased during the follow-up test compared to the baseline. According to the multivariate Cox proportional hazards model, the hazard ratio was 1.76 (95% confidence interval, 1.45-2.12; P < 0.001) in male subjects with an increased serum GGT level compared to male subjects with a decrease in the serum GGT level at follow-up compared to the baseline. However, the relationship between the serum ALT level and incidence of new-onset IFG was not statistically significant in both sexes; and in females, the relationship between the serum GGT level and incidence of new-onset IFG was also not statistically significant.

Conclusion: We revealed that a longitudinal increase in serum GGT levels was related to an increased risk of IFG in males. Therefore, monitoring the changes in serum GGT levels is important for predicting new-onset IFG, and it can be used as an early indicator of onset of overt diabetes in males.