Incidence of Type 1 diabetes mellitus and effect on mortality in young patients with congenital heart defect - A nationwide cohort study.

BACKGROUND

1% of all live born children are born with a congenital heart defect (CHD) and currently 95% reach adulthood. Type 1 diabetes mellitus (T1DM) is an autoimmune disease that can develop due to i.e. heredity, exposure to infections and stress-strain. The incidence of T1DM in patients with CHD is unknown and we analysed the risk of developing T1DM for patients with CHD, and how this influences mortality.

METHODS

By combining registries, the incidence of T1DM and the mortality was analysed in patients with CHD by birth cohort (1970-1993, 1970-1984 and 1984-1993) matched with population-based controls matched for sex, county and year of birth without CHD and followed from birth until a maximum of 42 years.

RESULTS

221 patients with T1DM among 21,982 patients with CHD and 1553 patients with T1DM among 219,816 matched controls were identified. The hazard ratio (HR) for developing T1DM was 1.50 (95%, CI 1.31-1.73) in patients with CHD compared to the controls and the first birth cohort (1970-1984) had the highest risk for T1DM, HR 1.87 (95%, CI 1.56-2.24). After onset, mortality risk was 4.21 times higher (95%, CI 2.40-7.37) in patients with CHD and T1DM compared to controls with T1DM.

CONCLUSION

From a nationwide cohort of patients with CHD and controls, the incidence of developing T1DM was 50% higher in patients with CHD, showing a significant increase in risk among birth cohort 1970-1984. The combination of CHD and T1DM was associated with a 4-fold increase in mortality compared to controls with only T1DM.