Liver enzymes, Type 2 diabetes, and metabolic syndrome in middle-Aged, Urban Chinese men

Background: We examined associations between elevated aspartate aminotransferase (AST) and alanine aminotransferase (ALT) with physical activity and obesity measures in middle-aged urban Chinese men. The associations between elevated aminotransferases with impaired fasting glucose, newly diagnosed type 2 diabetes (T2D), and metabolic syndrome were also evaluated in this population. Methods: The study included 3,978 urban Chinese men 40-74 years of age from a population-based cohort study, the Shanghai Men's Health Study, who were free of T2D at baseline and had provided fasting blood samples. Elevated AST and ALT levels were defined as >40U/L. Anthropometric measurements and information on lifestyle factors and disease history were collected by in-person interviews. Results: A total of 11.13% and 5.85% study participants had elevated serum ALT and AST levels, respectively. Both body mass index (BMI) and waist-to-hip ratio (WHR) were positively associated with elevated ALT and AST. We found stronger associations between ALT and BMI/WHR than between AST and BMI/WHR. Physical activity was inversely associated with ALT and AST, but the association was attenuated after adjustment for BMI and WHR. Elevated serum aminotransferase levels were associated with T2D and metabolic syndrome. Conclusions: In this representative sample of middle-aged Chinese men, elevated ALT and AST were associated with a prevalence of metabolic syndrome and T2D. These findings suggest that the relationship between obesity and T2D might involve liver injury. Physical activity might reduce the levels of ALT and AST, probably mediated through weight reduction.