Increased mortality in a Danish cohort of young people with Type 1 diabetes mellitus followed for 24 years.

Aim To determine the mortality rate in a Danish cohort of children and adolescents diagnosed with Type 1 diabetes mellitus compared with the general population. Methods In 1987 and 1989 we included 884 children and 1020 adolescents aged 20 years and under, corresponding to 75% of all Danish children and adolescents with Type 1 diabetes, in two nationwide studies in Denmark. Those who had participated in both investigations (n = 720) were followed until 1 January 2014, using the Danish Civil Registration System on death certificates and emigration. We derived the expected number of deaths in the cohort, using population data values from Statistics Denmark to calculate the standardized mortality ratio. Survival analysis was performed using Cox proportional hazards model. Results During the 24 years of follow-up, 49 (6.8%) patients died, resulting in a standardized mortality ratio of 4.8 (95% confidence interval 3.5, 6.2) compared with the age-standardized general population. A 1% increase in baseline HbA(1c) (1989), available in 718 of 720 patients, was associated with all-cause mortality (hazard ratio = 1.38; 95% confidence interval 1.2, 1.6; P < 0.0001). Type 1 diabetes with multiple complications was the most common reported cause of death (36.7%). Conclusion We found an increased mortality rate in this cohort of children and adolescents with Type 1 diabetes compared with the general population. The only predictor for increased risk of death up to 24 years after inclusion was the HbA(1c) level in 1989. This emphasizes the importance of achieving optimal metabolic control in young people with Type 1 diabetes.