Investigation of TyG-based metabolic indices and colorectal tumor risk: Evidence from the CHARLS and NHANES cohorts

Background Metabolic dysfunction and insulin resistance contribute to colorectal tumorigenesis, yet simple markers for early risk assessment remain limited. The triglyceride–glucose (TyG) index and its derivative indices capture key metabolic disturbances, but their associations with colorectal tumor risk across populations remain unclear. Methods Participants from CHARLS (n = 9,293) and NHANES (n = 2,839) were included. TyG-related indices were calculated from standard formulas. Associations with colorectal tumor risk were estimated using logistic regression. Subgroup effects and predictive performance were assessed using ROC analyses. Results All TyG-related indices were significantly higher in tumor cases than non-tumor participants in both cohorts. In CHARLS, fully adjusted models showed strong associations for TyG (OR = 3.98, 95% CI: 2.66–5.94), TyG-CI (OR = 2.00, 95% CI: 1.60–2.50), TyG-HGB (OR = 1.28, 95% CI: 1.20–1.36), and TyG-WWI (OR = 1.08, 95% CI: 1.06–1.11). Similar but weaker effects were observed in NHANES. RCS models demonstrated significant nonlinear relationships in both cohorts (all P for overall < 0.001), with clear metabolic thresholds (e.g., TyG: 10.88 in CHARLS; 9.93 in NHANES). Above these breakpoints, risk increased sharply. ROC analyses showed moderate discrimination in CHARLS (AUCs 0.767–0.786) and lower performance in NHANES (AUCs 0.570–0.587). Subgroup findings were broadly consistent across age, sex, lifestyle, and metabolic strata. Conclusions TyG and its derivative indices are consistently and nonlinearly linked to colorectal tumor risk across populations. Their metabolic thresholds suggest usefulness for early detection and risk stratification, supporting these indices as simple, low-cost markers for colorectal tumor risk.