Diabetic Retinopathy Enhances Coronary Artery Calcium-Based Cardiovascular Risk Stratification in Patients with Type 2 Diabetes: Insights from the ACCoDiab Study

Background The Coronary artery calcium (CAC) score is a validated imaging biomarker that is used in clinical practice to improve cardiovascular risk stratification in patients with type 2 diabetes (T2DM). However, residual risk remains, particularly in patients with moderate CAC. Diabetic retinopathy (DR), a microvascular complication of diabetes, may reflect systemic vascular vulnerability and provide additional prognostic information. Methods This observational cohort study was conducted as part of the primary prevention ACCoDiab study. Four hundred and twenty-four patients with T2DM and no prior history of cardiovascular events underwent CAC scoring and clinical assessment, including screening for DR. The study population comprised 175 females and 249 males, with an average age of 60.9 years. Patients were monitored for seven years for cardiovascular events, including nonfatal myocardial infarction, ischemic stroke, hospitalization for heart failure, revascularization of the limbs due to peripheral artery disease and cardiovascular death. Cox regression, Kaplan-Meier survival analysis, receiver operating characteristic (ROC) curves, and net reclassification improvement (NRI) were employed to evaluate the prognostic value of DR alongside CAC score with the aim of developing a simple cardiovascular risk score. Results Fifty patients (11.8%) experienced cardiovascular events. DR was significantly more prevalent among those who experienced events (58% vs. 25%, p < 0.001). Both CAC score and DR were independently associated with cardiovascular events. Combining the CAC and DR models significantly improved the prediction of events over the CAC model alone (AUC 75.3 vs. 67.8, p = 0.011), with even further improvement when adjusted for traditional risk factors (AUC 78.2, vs 71.3 p = 0.014 vs. the CAC model alone). The presence of DR reclassified a significant proportion of patients into higher risk categories, particularly among those with moderate CAC scores. Conclusion The combination of DR and CAC score significantly enhances cardiovascular risk stratification in patients living with T2DM, even after adjustment for traditional risk factors. Trial registration NCT03920683