Incidence of diabetes mellitus and effect on mortality in adults with congenital heart disease

Background Worldwide, 1–2% of children are born with congenital heart disease (CHD) with 97% reaching adulthood. Objectives This study aims to demonstrate the risk of diabetes in patients with CHD, and the influence of incident diabetes on mortality in CHD patients and controls. Methods By combining data from patient registries, the incidence of adult-onset diabetes registered at age 35 or older, and subsequent mortality risk were analysed in two successive birth cohorts (born in 1930–1959 and 1960–1983), by type of CHD lesion and sex, compared with population-based controls matched for sex and year of birth and followed until a maximum of 87 years of age. Results Out of 24,699 patients with CHD and 270,961 controls, 8.4% and 5.6%, respectively, were registered with a diagnosis of diabetes at the age of 35 or older, hazard ratio (HR) 1.47 (95% CI 1.40–1.54). The risk of diabetes was higher in the second birth cohort (HR of 1.74, 95% CI 1.54–1.95) and increased with complexity of CHD. After onset of DM, the total mortality among patients with CHD was 475 compared to 411/ 10,000 person-years among controls (HR 1.16, 95% CI 1.07–1.25). Conclusions In this nationwide cohort of patients with CHD and controls, the incidence of diabetes was almost 50% higher in patients with CHD, with higher risk in the most recent birth cohort and in those with conotruncal defects, with the combination of CHD and diabetes associated with a significantly increased mortality compared to diabetic controls.