Excess mortality in Finnish diabetic subjects due to alcohol, accidents and suicide: A nationwide study

Abstract

Aims: To characterize the burden of external causes of death attributable to alcohol-related causes, accidents and suicide among diabetic patients in a large national cohort. Methods: The population included diabetic individuals who had purchased and received reimbursement for at least one insulin prescription and/or one oral antidiabetic drug prescription between January 1997 and December 2010, and a non-diabetic reference population matched by sex, age and area. All new insulin users in this period were included, as well as 50% of new oral drug (OAD) users as a random sample. The data were collected by means of linkage from national registries. We analyzed the cohort data using Poisson regression models separately for each end-point and by gender (mortality rate ratio (MRR)). We subjected the case-cohort data to conditional logistic regression analysis based on exposure information within 1 year of the end-point event. The follow-up started on the date of the first diabetes medication prescription and ended on 31 December 2012 or on the date of death. Results: The study population comprised 434 629 individuals (226 372 men; diabetes population: 208 148 subjects, of whom 76% were treated only with OAD). The mean follow-up time was 7.1 years, during which there were 2832 deaths attributable to alcohol, 3187 to accidents and 853 to suicide. The diabetic subjects had higher mortality at almost all end-points, especially those treated with insulin: the adjusted MRRs for alcohol-related deaths were 1.71 for diabetic men treated with OAD and 6.92 for those on insulin; the respective MRRs for diabetic women were 2.10 and 10.60. There were more accident-related deaths among those treated with insulin (MRRs: 2.06 and 1.53 for men and women, respectively), and more suicides (MRR: 2.10 for men treated with insulin and 1.62 among women treated only with OAD). The results from the cohort study and the case-cohort study were rather similar. A time-dependent effect of diabetes was observed in alcohol-related mortality among men. Conclusions: The findings from this large nationwide cohort indicate higher mortality attributable to suicide, alcoholrelated causes and accidents among diabetic patients than among the non-diabetic population. The results emphasize the importance of effective psychosocial interventions among high-risk diabetic patients.