Prognostic value of the triglyceride-glucose (TyG) index for renal function progression in patients with CKD stages 3–4

Background The progression of chronic kidney disease (CKD) is a major public health issue. Insulin resistance (IR) is a key mechanism, but simple biomarkers to predict progression in patients with established CKD stages 3–4 are needed. The Triglyceride-glucose (TyG) index is a reliable surrogate for IR. We aimed to investigate the longitudinal association between the baseline TyG index and the risk of renal function progression in patients with CKD stages 3–4. Methods This multicenter retrospective cohort study included 53,607 patients with CKD stages 3–4 from the China Renal Data System (CRDS) between 2005 and 2022. The baseline TyG index was calculated, and participants were divided into quartiles. The primary outcome was renal function progression. We used multivariate Cox proportional hazards models, restricted cubic splines (RCS), subgroup analyses, and competing-risk models to assess the association. Results During a median follow-up of 31.18 months, 19,619 (36.6%) patients experienced renal function progression. After full multivariate adjustment, each 1-unit increase in the continuous TyG index was associated with a 10% higher risk of renal function progression (Hazard Ratio [HR] 1.10, 95% CI 1.07–1.12). Compared to the second quartile (Q2, reference), the highest quartile (Q4) had a significantly increased risk (HR 1.17, 95% CI 1.12–1.22). The RCS analysis revealed a non-linear, U-shaped association between the TyG index and renal function progression, with the lowest risk (nadir) at a TyG index of approximately 8.6–8.8. This U-shaped association was consistent across subgroup analyses and robust in sensitivity analyses, including a competing-risk model treating all-cause death as the competing event. Conclusion The TyG index is an independent predictor of renal function progression in patients with CKD stages 3–4, demonstrating a U-shaped relationship. As an inexpensive and readily available marker, the TyG index may serve as a valuable tool for early risk stratification in this high-risk population.