Diabetes mellitus and the risk of sudden cardiac death in patients with and without coronary artery disease

Background Diabetes is associated with sudden cardiac death (SCD), but evidence in patients without coronary artery disease (CAD) remains limited. SCD risk may vary by revascularisation strategy in diabetic patients with CAD. Methods We retrospectively analysed 22,395 consecutive patients undergoing coronary angiography from 2007 to 2018, either electively for suspected or known CAD or for acute coronary syndrome. Follow-up ended 31 December 2022. Sudden cardiac arrest (SCA), SCD and SCD-equivalent events were adjudicated using medical records, death certificates, and nationwide mortality data. Results Among 22,395 patients, 5,804 had diabetes. Over a median follow-up of 8.1 years (IQR 5.1–11.6), 1,710 experienced SCA, including 1,046 SCD or SCD-equivalent events. After multivariable adjustment including left ventricular ejection fraction (LVEF), diabetes showed similar associations with SCD or SCD-equivalent event (subdistribution hazard ratio [SHR] 1.38, 1.21–1.58; P < 0.001) and non-SCD death (SHR 1.37, 1.30–1.44; P < 0.001). Yet, among patients with diabetes, the 10-year cumulative incidence of non-SCA death was more than three times that of SCA. Diabetes was associated with SCD or SCD-equivalent event even without obstructive CAD (SHR 1.53, 1.11–2.12; P = 0.010). In patients with diabetes and CAD, lower SCD risk was observed in revascularized patients than in those receiving medical therapy (SHR 0.77, 0.60–0.99; P = 0.039). The diabetes–SCD association appeared stronger at age < 70 years, with LVEF ≥ 40%, in type 1 diabetes, and with higher HbA1c levels. Conclusions Diabetes was associated with SCD irrespective of obstructive CAD, but the high competing burden of non-SCA death highlights the challenge of SCA prevention and the importance of identifying higher-risk subgroups among patients with diabetes.