Prognostic Value of Coronary CT Angiography Among Patients With and Without Diabetes: The Mass General Brigham CCTA registry

This study aimed to assess the relationship between coronary CT angiography detected coronary artery disease (CAD) and long-term cardiovascular outcomes among individuals with and without diabetes mellitus (DM). A retrospective cohort study of patients undergoing CCTA at two medical centers between 2006 and 2024. Patients with prior CAD, advanced kidney disease, or malignancy were excluded. DM was defined by diagnostic codes or elevated hemoglobin A1c. CCTA findings were categorized as no CAD, nonobstructive CAD (1–49% stenosis), or obstructive CAD (≥ 50% stenosis). The primary outcome was a composite of cardiovascular death (CVD) or myocardial infarction (MI). Among 22,377 patients (median age 56 [IQR 47–65]; 45% women), 3,245 (14.5%) had diabetes. Individuals with diabetes were older and had more cardiovascular risk factors. Obstructive CAD was more frequent in patients with diabetes (33% vs. 19%), whereas no CAD was less common (23% vs. 42%). Over a median follow-up of 6 years (IQR 3.9–9.5), the primary outcome occurred more than twice as often among those with diabetes (7.8% vs. 3.1%; P < 0.001). Event rates increased with CAD severity and remained higher among individuals with diabetes across all categories. After adjustment, obstructive CAD remained significantly associated with the primary outcome in both groups (DM: HR 2.9 [95% CI 1.8–4.6], P < 0.001; non-DM: HR 2.7 [95% CI 2.1–3.4]), p < 0.001). Among patients undergoing CCTA, CAD was more frequent and severe in those with diabetes, and the risk of CVD or MI increased with CAD severity, approximately doubling in each category when diabetes was present.