The Triglyceride-Glucose Index as a Biomarker for Insulin Resistance Following Hepatitis C Virus Eradication: A Prospective Cohort Study

Background: The triglyceride-glucose (TyG) index has emerged as a novel surrogate marker of insulin resistance, but its changes after hepatitis C virus (HCV) eradication remain unclear. This study aimed to evaluate changes in the TyG index following direct-acting antiviral (DAA) treatment. Methods: HCV-infected patients achieving sustained virological response 12 weeks post-treatment (SVR12) were prospectively enrolled from May 2015 to June 2023. Exclusion criteria included the following: (1) failure to achieve SVR12; (2) use of anti-diabetes or anti-hyperlipidemia medications; and (3) hepatitis B virus or human immunodeficiency virus co-infection. Changes in lipid profiles, TyG index, and homeostasis model assessment of insulin resistance (HOMA-IR) were evaluated from baseline to SVR12. Insulin resistance was defined as HOMA-IR ≥ 2.5. The optimal TyG index cut-off for predicting insulin resistance was determined using the Youden Index. Results: A total of 111 patients (median age: 61.0 years; 45.9% male) were included. The TyG index correlated positively with HOMA-IR (Pearson’s r = 0.32, p < 0.001). Among patients with pre-existing insulin resistance, significant improvements were observed at SVR12 in both HOMA-IR (4.0 [IQR: 3.1–5.4] vs. 2.5 [IQR: 2.0–3.9]; p < 0.001) and TyG index (8.47 [IQR: 8.08–8.68] vs. 8.36 [IQR: 8.00–8.71]; p = 0.028). Using 8.27 as the optimal TyG index cut-off, similar improvements were noted in HOMA-IR (2.8 [IQR: 2.0–4.3] vs. 2.3 [IQR: 1.5–3.8]; p = 0.031) and TyG index (8.62 [IQR: 8.46–8.83] vs. 8.52 [IQR: 8.27–8.89]; p = 0.003). Conclusions: The TyG index is a valuable tool for monitoring changes in insulin resistance after HCV eradication, particularly in patients with baseline insulin resistance.