Assessment of the Association Between Cardiac Metabolic Markers and Carotid Atherosclerosis, and the Role of Insulin Resistance.

Background: Obesity is a growing global health concern. The cardiometabolic index (CMI), a novel marker of fat distribution, has been proposed as a potential risk indicator. This study investigates the association between CMI and carotid atherosclerosis (CAS), as assessed by carotid intima-media thickness (cIMT), and explores whether insulin resistance (IR) mediates this relationship.

Methods: This cross-sectional study enrolled type 2 diabetes mellitus (T2DM) patients hospitalized at Cangzhou People's Hospital between September 2024 and March 2025. Logistic regression models, restricted cubic spline (RCS) analysis, and subgroup analysis were used to examine the CMI-CAS relationship. The predictive ability of CMI was assessed using receiver operating characteristic (ROC) curves, and its incremental value beyond traditional risk factors was evaluated by integrated discrimination improvement (IDI) and net reclassification improvement (NRI). Mediation analysis assessed the role of IR.

Results: After adjustment, higher CMI was significantly associated with increased odds of CAS (OR = 1.48, 95% CI: 1.21-1.81, P < 0.001). RCS analysis showed a nonlinear relationship between CMI and CAS. ROC analysis indicated moderate predictive power (AUC = 0.65, 95% CI: 0.61-0.68). Including CMI improved prediction with an IDI of 0.04 (P < 0.001) and an NRI of 0.26 (P < 0.001). Subgroup analysis revealed a significant interaction with T2DM duration (P = 0.013). Mediation analysis showed that metabolic score for insulin resistance (METS-IR) partially mediated the CMI-CAS relationship, explaining 12.92% of the total effect.

Conclusion: Elevated CMI is independently associated with higher risk of CAS in T2DM patients, and insulin resistance partially mediates this relationship. CMI may be a valuable marker for early vascular risk stratification in diabetic populations.