Mortality in childhood-onset type 1 diabetes

OBJECTIVE - To describe the age- and sex-specific mortality in a cohort of young type 1 diabetic patients and to analyze the causes of death with special focus on suicide, accidents, and unexplained deaths. RESEARCH DESIGN AND METHODS - A population-based incident childhood diabetes register, covering onset cases since 1 July 1977, was linked to the Swedish Cause of Death Register up to 31 December 2000. The official Swedish population register was used to calculate age- and sex-standardized mortality rates (SMRs), excluding neonatal deaths. To analyze excess risks for specific diagnoses, case subjects were compared with five nondiabetic control subjects, matched by age, sex, and year of death. Death certificates were collected for all case and control subjects. For case subjects with an unclear diagnosis, hospital records and/or forensic autopsy reports were obtained. RESULTS - Mean age- and sex-SMR was 2.15 (95% CI 1.70-2.68) and tended to be higher among females (2.65 vs. 1.93, P = 0.045). Mean age at death was 15.2 years (range 1.2-27.3) and mean duration 8.2 years (0-20.7). Twenty-three deaths were clearly related to diabetes; 20 died of diabetic ketoacidosis. Only two case subjects died with late diabetes complications (acute coronary infarction). Thirty-three case subjects died with a diagnosis not directly related to diabetes; 7 of them committed suicide, and 14 died from accidents. There was no significant difference in traffic accidents (odds ratio 1.02 [95% CI 0.40-2.37]). Obvious suicide tended to be increased but not statistically significantly so (1.55 [0.54-3.89]). Seventeen diabetic case subjects were found deceased in bed without any cause of death found at forensic autopsy. Only two of the control subjects died of similar unexplained deaths. CONCLUSIONS - in a well-developed health care system, there is still a significant excess mortality in young type 1 diabetic patients. We confirm a very large proportion of unexplained deaths in bed, which should be further studied. There is no clear excess death rate caused by suicide or traffic accidents among young diabetic subjects.