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

Abstract

Introduction Patients with diabetes mellitus are known to have markedly higher mortality due to cardiovascular diseases, cancer and renal causes, whereas the mental strains imposed by chronic diseases and substance abuse as well as the accidental causes of excess mortality have gained relatively little attention. Mental symptoms and diseases are common among diabetic patients, such as depression and suicidal ideation. A recent meta-analysis [1] found that diabetes was associated with a significantly increased risk of suicide, especially in insulin-deficient (type 1) diabetic patients. Methods We have analyzed the intertwined external causes of death due to alcohol-related causes, accidents and suicides in a large national cohort containing all the patients treated with insulin and a random sample of half of those treated with oral antidiabetic drugs as being matched with a reference population. The study population was constructed based on the data of CARING Project [2] in Finland ( http://www.caring-diabetes.eu/ ). The study population consisted of 475,360 individuals, 220,110 men and 206,472 women. We used suicides and sequelae of intentional self-harm, accidents, and alcohol-related diseases and accidental poisoning by alcohol as the endpoint events. We categorized subject into four groups by the diabetes drug at the start of the follow-up: no DM (reference), only oral antidiabetic drugs (OAD), OAD and insulin, and only insulin. The following variables were adjusted for age, calendar year in start of follow-up, usage of statins, usage of HRT, time since start of follow-up, cancer before start of follow-up, and hospital district. Adjusted mortality rate ratios (MRR) were estimated using Poisson regression model. Separate models were calculated for men and women. Results The mean follow-up time was 6.6 years and 2.8 million person-years were cumulated during follow-up. We observed 2716 deaths caused due to alcohol-related causes, 3220 due to accidents, and 832 due to suicides. All diabetic groups, both men and women, had higher risk of alcohol-related death. Risk was high especially in insulin group, with MRR for men 4.56 (95% CI: 4.12, 5.05) and for women 4.32 (2.99, 6.24). Similar pattern was observed in accidents. MRR varied between men with OAD only group 1.16 (1.03, 1.30) and women in insulin only group 1.71 (1.47, 1.98). Also risk of suicide were higher in diabetics with highest MRR 2.04 (1.48, 2.81) in women in OAD only group. Conclusions To conclude, we found in this large nationwide cohort that diabetic patients showed higher mortality due to suicides, alcohol-related causes and accidents than nondiabetic population, and that this premature mortality was most clearly associated with the use of insulin, reflecting the severity of diabetes, and with male gender. These findings underscore the importance of identifying high-risk patients early enough as well as effective psychosocial support and interventions among these individuals.