Background: The aspartate aminotransferase (AST) to alanine aminotransferase (ALT) ratio has been demonstrated to be associated with insulin resistance and metabolic syndrome. However, few studies have directly explored the association between the AST/ALT ratio and the incidence of type 2 diabetes mellitus (T2DM). As such, the present study aimed to investigate the relationship between the AST/ALT ratio and incident T2DM during follow-up in a population-based cohort.
Methods: This retrospective cohort analysis included 15,464 Japanese males and females without DM at baseline between 2004 and 2015. The association between AST/ALT ratio and T2DM was retrospectively examined using the Cox proportional hazard model after adjusting for multiple potential confounders.
Results: After follow-up, 373 (2.41%) patients developed T2DM. A nonlinear relationship between the AST/ALT ratio and T2DM was observed after adjusting for potential confounders. The risk for developing T2DM decreased with AST/ALT ratio up to a threshold of 0.93 (adjusted hazard ratio [HR] 0.14 [95% confidence interval (CI) = 0.02– 0.90; P = 0.0385]). An AST/ALT ratio > 0.93 was not associated with the risk for developing T2DM (adjusted HR = 0.67, 95% CI = 0.17– 2.65; P = 0.5718).
Conclusion: The AST/ALT ratio was associated with a lower incidence of T2DM in a nonlinear pattern. The threshold AST/ALT ratio for developing T2DM was 0.93. AST/ALT levels were inversely correlated with the occurrence of T2DM when AST/ALT ratio ≤ 0.93.
Keywords: AST, ALT, diabetes mellitus, follow-up, nonlinear association