Interpreting the triglyceride-glucose index and its derived indices in metabolic dysfunction-associated steatotic liver disease: clinical utility and evidence gaps.

Metabolic dysfunction-associated steatotic liver disease (MASLD) is common, yet early disease often remains unrecognized. The triglyceride-glucose (TyG) index, calculated from fasting triglyceride and glucose concentrations, has emerged as an accessible surrogate marker of metabolic dysfunction. This review examines the clinical interpretation, biological context, and current limitations of the TyG index and its anthropometric and inflammatory derivatives in MASLD. Current evidence links higher TyG-related measures to prevalent steatosis, fibrosis markers, and selected extrahepatic outcomes. Indices incorporating body mass index, waist circumference, or waist-to-height ratio may improve risk discrimination in some settings, particularly when body-fat distribution is informative. However, their performance varies according to population characteristics, disease definition, reference standard, and clinical purpose. TyG is not a direct measure of hepatic or peripheral insulin resistance, liver inflammation, or fibrosis. It should therefore be considered a metabolic risk marker rather than a stand-alone diagnostic test for MASLD or MASH. Important limitations include the predominance of cross-sectional evidence, heterogeneity among NAFLD, MAFLD, and MASLD definitions, variable cutoff values, and component overlap between TyG-derived indices and cardiometabolic diagnostic criteria. Evidence for liver-specific hard outcomes remains limited. Future studies should directly compare TyG-related markers with established metabolic and liver-directed tests in diverse prospective cohorts, using standardized repeated measurements and outcomes including progressive fibrosis, cirrhosis, hepatocellular carcinoma, and liver-related death. At present, TyG-related measures may complement, but cannot replace, liver-specific assessment.