Combined effect of serum gamma-glutamyltransferase and uric acid on incidence of diabetes mellitus: A longitudinal study.

Gamma-glutamyltransferase (GGT) and uric acid (UA) are novel diabetes risk factors. However, little is known about the combined effects of GGT and UA on the development of diabetes. Here, we assessed the combined effects of GGT and UA on the development of diabetes in a Korean population.We evaluated 1983 women and 2687 men without diabetes. From the baseline health screening to the follow-up examination, the development of diabetes, based on changes in GGT and UA quartile levels, was analyzed. Furthermore, the quartile of GGT and quartile of UA were analyzed together to determine any synergistic effect from the 4th quartile of GGT and UA on the development of diabetes.In women, the development of diabetes gradually increased with an increase in the circulating levels of GGT and UA. For the highest quartile of GGT and UA, hazard ratios of diabetes compared with the lowest quartile were 3.88 (95% confidence interval [CI]: 1.12-13.43, P = .032) and 7.58 (95% CI: 2.17-26.42, P = .002) after adjusting for confounders, respectively. Hazard ratios of diabetes after combining both 4th quartiles of GGT and UA were 5.29 (95% CI: 1.87-15.18, P = .002), as compared with the first and second quartiles. In men, however, the development of diabetes was not significantly different among the quartiles of UA.GGT and UA levels can synergize in predicting the development of diabetes in Korean women.