Diagnostic Utility of Triglyceride-Glucose Index in Non-Alcoholic Fatty Liver Disease: A Cross-Sectional Study on Lean Population

Background: Approximately 10–20% of individuals with non-alcoholic fatty liver disease (NAFLD) are lean, and the underlying pathophysiology is not yet understood. This study aims to explore the characteristics and the diagnostic value of triglyceride-glucose index (TyG) in early diagnosis of lean NAFLD. Methods: 99 patients with lean NAFLD and 1891 healthy controls were included in the health examination. The characteristics were compared between groups. Restricted cubic spline was utilized to analyze the relationship between TyG index and the risk of lean NAFLD. Logistic regression and receiver operating curve (ROC) were applied to explore the diagnostic value of TyG index for lean NAFLD. Results: Overall, 99 (4.97%) patients had lean NAFLD. Patients with lean NAFLD have significant abnormal glycolipid metabolism and higher TyG index. Restriction cube spline analysis showed a significant dose-response relationship between the TyG index and risk of lean NAFLD. After adjusting for confounders, the relationship remained and the risk of developing lean NAFLD increased 2.99 times for per unit increase of TyG index (95% CI: 1.94, 4.67, P<0.001). The areas under the ROC of the TyG index for lean NAFLD detection were 0.851 (0.815 to 0.886). Conclusion: The TyG index is positively associated with the risk of developing lean NAFLD and could be a useful marker for early diagnosis of lean NAFLD.