Elevated Liver Function Enzymes Are Related to the Development of Prediabetes and Type 2 Diabetes in Younger Adults: The Bogalusa Heart Study

OBJECTIVE: Elevations in alanine aminotransferase (ALT) and γ-glutamyl transferase (GGT), surrogate markers of liver dysfunction and nonalcoholic fatty liver, are considered as part of metabolic syndrome and related type 2 diabetes. However, information is limited regarding the long-term predictability of ALT and GGT in the development of prediabetes and type 2 diabetes. RESEARCH DESIGN AND METHODS: In this retrospective cohort study, normoglycemic (n = 874), prediabetic (n = 101), and diabetic (n = 80) adults aged 26–50 years (average age 41.3 years) were followed over an average period of 16 years since their young adulthood (aged 18–38 years, average age 25.1 years), with measurements of cardiometabolic risk factor variables including ALT and GGT. RESULTS: The follow-up prevalence rate of adult diabetes status by quartiles of baseline ALT and GGT levels showed an adverse trend for both prediabetes (P < 0.05) and diabetes (P < 0.01). In a longitudinal multivariate logistic regression analysis that included anthropometric, hemodynamic, and metabolic variables, as well as alcohol consumption and smoking, individuals with elevated baseline ALT and GGT levels (per 1-SD increment) were 1.16 and 1.20 times, respectively, more likely to develop diabetes (P = 0.05 for ALT and P < 0.01 for GGT); no such associations were noted for prediabetes. Regarding the predictive value of ALT and GGT, the area under the receiver operating curve analysis yielded C values ranging from 0.70 to 0.82, with values significantly higher for diabetes compared with prediabetes. CONCLUSIONS: These findings in younger adults suggest potential clinical utility of including ALT and GGT as biomarkers in diabetes risk assessment formulations.