Depression, Diabetes Mellitus and Mortality in Older Adults: A National Cohort Study in Taiwan

Purpose: Diabetes mellitus (DM) increases the risk of cardiovascular and all-cause mortality. The coexistence of depression and DM is associated with an increased risk of DM complications and functional morbidity. The independent effect of depression on mortality in patients with DM is unclear, and relevant Asian studies have provided inconsistent results. Accordingly, this study assessed the independent and additive effects of DM and depression on mortality in a nationally representative cohort of older adults in Taiwan over a 10-year observation period. Patients and Methods: A total of 5041 participants aged 50 years or older were observed between 1996 and 2007. We defined depression as a score of ≥8 on the 10-item Center for Epidemiologic Studies Depression (CES-D 10) scale. Additionally, we defined participants as having type 2 DM if they had received a diagnosis of type 2 DM from a health-care provider. Cox proportional hazard models were applied to analyze predictors of mortality in depression and DM comorbidity groups. Results: During the 10-year follow-up period, 1637 deaths were documented. After adjustment for potential confounders, the hazard ratios for mortality in participants with both depression and DM, DM only, and depression only were 2.47 (95% confidence interval [CI]: 2.02–3.03), 1.95 (95% CI: 1.63–2.32), and 1.23 (95% CI: 1.09–1.39), respectively. Conclusion: The co-occurrence of depression with DM in Asian adults increased overall mortality rates. Our results indicate that the increased mortality hazard in individuals with DM and depression was independent of sex.