Considering serum alanine aminotransferase and gamma-glutamyltransferase levels together strengthen the prediction of impaired fasting glucose risk: a cross-sectional and longitudinal study

Emerging data suggest that an increase in serum alanine aminotransferase (ALT) and gamma-glutamyltransferase (GGT) as biomarkers of oxidative stress are associated with increased risk of impaired fasting glucose (IFG). The present study was an investigation of whether an increase in serum ALT and GGT had a combined effect on increasing IFG risk through cross-sectional and longitudinal studies. In the cross-sectional study, data were analyzed from 9937 subjects without diabetes who underwent health check-ups between 1999 and 2001 (baseline data). In the longitudinal study, 6390 subjects were analyzed who had been rechecked between 2009 and 2014, excluding IFG patients from baseline data. In cross-sectional analysis, adjusted odds ratio (OR) of IFG in the fourth quartile of both ALT and GGT was 1.829 (95% confidence interval [CI] 1.545–2.164) compared with the reference group (1st and 2nd quartiles of ALT and GGT). In longitudinal analysis, IFG probability increased gradually with an increase in the circulating levels of ALT and GGT. Adjusted hazard ratios for developing IFG in the fourth quartile of both ALT and GGT was 1.625 (95% CI 1.263–2.091) compared with the reference group (1st and 2nd quartiles). Increased serum ALT and GGT levels are well associated with IFG after potential confounders are adjusted for, and elevated ALT and GGT at the same time can have a combined effect in predicting the development of IFG.