Association between the C-reactive protein-triglyceride glucose index and carotid atherosclerosis in patients with type 2 diabetes mellitus

Background The C-reactive protein-triglyceride glucose index (CTI), as a novel marker reflecting insulin resistance (IR) and inflammation, has been investigated in various diseases. However, the association of CTI with carotid atherosclerosis (CA) in patients with type 2 diabetes mellitus (T2DM) remains unclear. This study aimed to investigate the association between CTI and CA, which was assessed by carotid plaque and intima-media thickness (IMT) in patients with T2DM. Methods This retrospective cross-sectional study analyzed 938 patients with T2DM. The CTI was calculated using the formula: 0.412×Ln[CRP (mg/L)]+Ln[(TG (mmol/L)×88.57×FPG (mmol/L)×18.02)/2]. Logistic regression models were adopted to analyze the connection of CTI with carotid plaque, and linear regression models were used to explore the association of CTI with carotid IMT. Receiver operating characteristic (ROC) curves, integrated discrimination improvement (IDI), and net reclassification improvement (NRI) were used to assess discrimination and reclassification of prevalent carotid plaque. Results Among the 938 enrolled patients with T2DM, carotid plaques were detected in 438 participants (46.7%). Patients with carotid plaques had significantly higher CTI levels than those without plaques (9.98 ± 0.775 vs. 9.27 ± 0.664, P<0.001). After full adjustment, each one-unit increase in CTI was associated with higher odds of carotid plaque [odds ratio (OR) 4.189; 95% CI: 3.281-5.744; P<0.001] and greater carotid IMT (P = 0.016). When CTI was categorized into quartiles, compared with the lowest quartile, the highest quartile had an OR of 10.909 (95% CI: 6.982-17.521; P<0.001). The area under the ROC curve (AUC) showed superior discriminative performance of CTI for carotid plaque, with an AUC of 0.743, significantly higher than that of CRP (AUC 0.611; P<0.001) and the TyG index (AUC 0.655; P<0.001). When CTI was added to the base clinical model, the AUC increased from 0.737 to 0.820 (P<0.001), with an IDI of 13.5% and an NRI of 26.2%. Conclusion In patients with T2DM, elevated CTI levels are independently associated with the presence of carotid plaque and greater carotid IMT.