Associations of TyG-related indices with NAFLD-related outcomes: A systematic review and meta-analysis

BACKGROUND: The triglyceride-glucose (TyG) index and related composite indices have been increasingly studied as accessible metabolic markers for fatty liver disease. However, evidence remains difficult to interpret because different TyG-related indices have been evaluated across heterogeneous populations and nonalcoholic fatty liver disease (NAFLD)-related outcomes. We conducted a systematic review and meta-analysis to clarify the pooled associations that could be formally synthesized and to summarize the broader descriptive evidence. METHODS: We systematically searched PubMed, Embase, the Cochrane Library, China National Knowledge Infrastructure, Wanfang Data, VIP Database, and China Biology Medicine Database from inception to December 2025. Observational studies evaluating the TyG index or related composite indices, including TyG-body mass index, TyG-waist circumference, and TyG-waist-to-height ratio, in relation to NAFLD-related outcomes were eligible. Random-effects meta-analyses were performed in R. Only studies with sufficient comparability in exposure operationalization, outcome definition, and effect-size reporting were quantitatively pooled; the remaining studies were retained in the descriptive synthesis. RESULTS: Nineteen studies involving 212,618 participants were included in the systematic review, including 16 cross-sectional studies and 3 cohort studies. Of these, 8 studies contributed to at least 1 quantitative synthesis. In continuous-scale analyses, higher TyG levels were associated with increased odds of NAFLD/steatosis (5 studies; pooled odds ratio [OR], 2.72; 95% confidence interval [CI], 2.08-3.55; I2 = 85.7%). In highest-versus-lowest analyses, the association remained significant (4 studies; pooled OR, 4.36; 95% CI, 3.39-5.61; I2 = 92.8%). TyG-body mass index (2 studies; pooled OR, 1.04; 95% CI, 1.03-1.05; I2 = 0.0%) and TyG-waist circumference (2 studies; pooled OR, 1.01; 95% CI, 1.01-1.01; I2 = 15.1%) were also positively associated with NAFLD/steatosis. TyG-waist-to-height ratio showed a positive association in supportive synthesis, but evidence for liver fibrosis and nonalcoholic steatohepatitis remained limited and was mainly descriptive. CONCLUSION: TyG-related indices were consistently associated with NAFLD/steatosis across the available literature. The basic TyG index had the broadest evidence base, whereas composite indices suggested possible additional value in selected settings. These markers may be useful for metabolic fatty liver risk stratification, but further studies with standardized outcome definitions and clearer exposure parameterization are needed.