Depression shortens life expectancy in diabetes

More than treatment nonpersistence, depression exerts a deleterious effect on all-cause and cardiovascular-related mortality in individuals with type 2 diabetes (T2D), according to a study.

The nested case-control study involved a cohort of newly treated individuals with diabetes residing in Canada. Each patient was matched with up to 10 controls by age, sex, follow-up, and comorbidity index.

The Quebec administrative data facilitated identification of all-cause, diabetes-related, cardiovascular-related and major cardiovascular event deaths during a maximum follow-up of 8 years. There were 13,558 deaths documented, of which 3,652 were related to cardiovascular diseases, 2,112 to major cardiovascular events, and 311 to diabetes.

Conditional logistic regression model adjusted for nonpersistence to antidiabetic drug treatment showed that depression contributed to an increased risk of all-cause and cardiovascular-related deaths (odds ratio range, 1.32 (95 percent confidence interval [CI], 1.21–1.45) to 1.72 (95 percent CI, 1.57–1.88).

The present data highlight the importance of identifying risk factors for depression and implementing a screening and proper treatment for depression to help reduce mortality.

There are multiple pathways explaining the mechanisms underlying the association between comorbid depression and increased risk of death in T2D. First is the direct effect of the psychological disorder on physiological factors may lead to an increase in classic metabolic risk factors. [PLoS One 2013;doi:10.1371/journal.pone.0079809]

Meanwhile, indirect pathways refer to psychosocial and behavioural factors, with depression being associated with poor health behaviour (eg, smoking, a poor diet), maladaptive coping style, social isolation, and chronic life stress. Coexisting depression and diabetes are also associated with changes in the neuroendocrine system, increased immunoinflammatory activation, heightened risk of diabetes complications, and poor adherence to glucose-lowering drugs. [PLoS One 2013;doi:10.1371/journal.pone.0079809]