Relationship between triglyceride-glucose index and aminotransferase among Royal Thai Army personnel 2017–2021: a serial cross-sectional study

BACKGROUND: Insulin resistance (IR) is a major pathogenesis of nonalcoholic fatty liver disease (NAFLD). The triglyceride-glucose (TyG) index has recently gained popularity to assess IR and NAFLD due to its simplicity and low cost. The aim of the current study was to evaluate the relationship between the TyG index and aminotransferase. METHODS: A serial cross-sectional study was conducted among 232,235 Royal Thai Army (RTA) personnel aged 35–60 years from 2017–2021. Elevated aminotransferase was defined as ≥ 40 U/L and ≥ 35 U/L among males and females, respectively. A linear regression analysis between the TyG index and log-transformed aminotransferase was performed. High- and low-TyG index groups were divided according to Youden’s index cut point for predicting elevated aminotransferase. Multivariable logistic analysis was also utilized to investigate the association between the TyG index and elevated aminotransferase. RESULTS: The TyG index revealed a dose‒response relationship with log-transformed aminotransferase in both sexes and all age groups. The TyG index was positively associated with the prevalence of elevated aminotransferases. In comparison with the first TyG quartile (< 8.37), participants in the fourth quartile (> 9.23) had a higher chance for elevated ALT (AOR: 2.81, 95% CI: 2.71–2.90 for males and AOR: 4.01, 95% CI: 3.50–4.60 for females, P < 0.001 for both). In the fourth TyG quartile, the prevalence of elevated ALT was 47.8% and 40.2% in the participants aged 35–44 and male participants, respectively. CONCLUSION: A high TyG index is a novel risk factor for elevated aminotransferase among RTA personnel. Those with a high TyG index should be screened for elevated aminotransferase, particularly males aged 35–44 years. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1186/s12944-023-01811-5.