Association Between the Triglyceride–Glucose Index and Outcomes of Nonalcoholic Fatty Liver Disease: A Large-Scale Health Management Cohort Study

BACKGROUND: Nonalcoholic fatty liver disease (NAFLD) is increasingly becoming a major health burden. Due to the difficulty of liver biopsy, there is no reliable indicator to evaluate the outcomes of NAFLD. The triglyceride–glucose (TyG) index is a simple and convenient marker of insulin resistance for use in medical practice. Whether the TyG index is predictive of later risk of NAFLD remains unknown. OBJECTIVE: To evaluate the relationship between TyG index with NAFLD progression and improvement during a median follow-up period of 21 months. MATERIAL AND METHODS: A total of 11,424 subjects (9327 men) diagnosed with NAFLD were included. The TyG index was calculated as follows: ln [fasting triglycerides (mg/dL) * fasting glucose (mg/dL)/2]. Multivariable Cox regression analysis was applied to analyze the data. RESULTS: In this study, the severity of NAFLD remained the same in 38.8% of subjects, worsened in 17.4% of subjects, and improved in 43.8% of subjects. Compared with the lowest quartile of the TyG index, the adjusted HR of NAFLD progression in the highest quartile (TyG≥9.34) was 1.448 (1.229 to 1.706), and the adjusted HR of NAFLD improvement was 0.817 (0.723 to 0.923). Subgroup analysis found that smoking increased the correlation between the TyG index and the risk of NAFLD progression, while female, vegan diet, and weight control enhanced the correlation between the TyG index and the risk of NAFLD improvement. CONCLUSION: The TyG index may be a simple and helpful indicator for further risk appraisal of NAFLD in daily clinical practice.