Unnatural deaths in a national cohort of people diagnosed with diabetes.

OBJECTIVE: To examine risk of unnatural death among people diagnosed with diabetes irrespective of disease type. RESEARCH DESIGN AND METHODS: We conducted a matched cohort study of the entire Swedish population using interlinked national registers. From the National Diabetes Register we identified 252,191 people diagnosed with diabetes (type 1 or 2) during 1996-2009. Each cohort member was matched for age, sex, and county of birth to five unaffected individuals randomly sampled from the Total Population Register. Mortality was examined with complete ascertainment, and risk ratios (RRs) for all unnatural deaths and for specific causes (suicide, accident, homicide, and iatrogenic effects) were estimated using conditional fixed-effects Poisson regression. RESULTS: Risk of any unnatural death was elevated versus the general population: 77.3 versus 32.1 per 10,000 (RR 2.2 [95% CI 2.1-2.4]), and these deaths occurred at a younger age in the diabetes cohort. Risk was increased for suicide (RR 3.4 [95% CI 3.0-3.8]), accident (RR 2.0 [95% CI 1.9-2.1]), homicide (RR 3.1 [95% CI 1.6-6.1]), and iatrogenic effects (RR 2.4 [95% CI 1.9-3.2]). It was greatly elevated for fatal poisoning from a variety of agents, including psychotropic drugs and "other and unspecified medication," as well as narcotics, alcohol, and carbon monoxide. Almost 9% of all fatal poisoning cases in the diabetes cohort were identified as overdoses of insulin or oral hypoglycemic drugs. CONCLUSIONS: Various causes of unnatural death, in particular deliberate and accidental poisonings, occur more frequently among diabetic patients. Before preventive strategies can be implemented, a deeper understanding of the risk factors and causal mechanisms explaining the marked elevations in risk is needed.