TyG index and progression of diabetic kidney disease in type 2 diabetes: A retrospective cohort study

OBJECTIVE: To investigate the independent association between the triglyceride-glucose (TyG) index and diabetic kidney disease (DKD) progression in patients with type 2 diabetes mellitus (T2DM). MATERIALS AND METHODS: A retrospective study included a NHANES cohort (2003 - 2020, n = 4,086) and a clinical cohort (n = 535, median follow-up 36 months). Weighted logistic regression, Cox regression, restricted cubic splines, and ROC curves were used. RESULTS: In the NHANES cohort, each 1-unit increase in the TyG index was associated with a 56.4% higher risk of prevalent DKD (OR = 1.56, 95% CI: 1.06 - 2.31). A linear positive association and a threshold of 8.19 were identified; above this, risk increased significantly (OR = 1.82). The association was significant in males (OR = 1.61) but not females. In the clinical cohort, a high TyG index (≥ 8.19) independently predicted DKD progression (HR = 1.53, 95% CI: 1.01 - 2.30). Kaplan-Meier curves showed significant differences across TyG groups (log-rank p < 0.001). The AUC for predicting progression was 0.71 (95% CI: 0.68 - 0.74). Sex-stratified analysis confirmed significance only in males (HR = 1.85). CONCLUSION: The TyG index shows a significant overall association with DKD progression, with a threshold effect at 8.19. Sex-stratified analysis revealed that this association was statistically significant only in male patients. These findings suggest that the TyG index may serve as a convenient and cost-effective early risk predictor for DKD, particularly in male diabetic patients. The observed sex heterogeneity warrants further investigation into the potential role of hormonal factors.