In the present study, the main findings were that the TyG–ALT index showed a role as a surrogate marker for IR in NAFLD and had a significant association with US-FLI after adjusting for sex, age, and BMI, and TyG–ALT was an independent risk factor for NASH risk in NAFLD patients and superior to both ALT and the TyG index for predicting the severity of NAFLD. The gene discussed is GPT; the disease is metabolic dysfunction-associated steatohepatitis.