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 personyears 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.