The association between the cumulative C-reactive protein-triglyceride-glucose index and the incidence of cardiovascular disease in middle-aged and elderly Chinese individuals of abnormal glucose metabolism

To evaluate the association between the cumulative C-reactive protein–triglyceride–glucose index (cumCTI) and incident cardiovascular disease (CVD) and stroke in Chinese adults aged ≥ 45 years with impaired glucose metabolism, and to compare its predictive performance with its individual components. A total of 2,980 participants from the CHARLS study were included, with a median follow-up of 3.0 years. cumCTI was calculated from CTI measurements at Wave 1 and Wave 3. Cox proportional hazards models with sequential adjustment were used to estimate the association between cumCTI and outcomes. Restricted cubic splines (RCS) were applied to examine dose–response relationships. Weighted quantile sum (WQS) regression and causal mediation analyses were performed to explore component contributions and underlying mechanisms. Predictive performance was compared using Harrell’s C-index, and subgroup analyses were conducted to test the robustness of the findings. During follow-up, 440 CVD events occurred, including 182 strokes. In fully adjusted models, each 1-unit increase in cumCTI was associated with a 9.0% higher risk of stroke (HR = 1.090, 95% CI: 1.025–1.160, P = 0.006) and a 4.3% higher risk of CVD (HR = 1.043, 95% CI: 1.001–1.087, P = 0.045), both exhibiting linear dose–response relationships. Mean arterial pressure mediated 15.6% of the effect on stroke and 12.5% on CVD. WQS analysis revealed that triglycerides contributed 72.70% (stroke) and 80.78% (CVD) of the predictive weight, whereas C-reactive protein contributed only 0.20% and 7.81%, respectively. The C-index of cumCTI (0.5639) did not surpass that of TyG (0.5744). The association with stroke was stronger than that with CVD. cumCTI is linearly and positively associated with both stroke and CVD in individuals with impaired glucose metabolism, partially mediated by blood pressure. However, cumCTI does not outperform its core component TyG, and CRP contributes minimally to stroke prediction. TyG is recommended as a simpler, more cost-effective screening marker, and stroke prevention should prioritize comprehensive management of blood glucose, lipids, and blood pressure.