Type 2 Diabetes and Comorbid Symptoms of Depression and Anxiety: Longitudinal Associations With Mortality Risk

Depression is strongly linked to increased mortality in individuals with type 2 diabetes. Despite high rates of co-occurring anxiety and depression, the risk of death associated with comorbid anxiety in individuals with type 2 diabetes is poorly understood. This study documented the excess mortality risk associated with symptoms of depression and/or anxiety comorbid with type 2 diabetes.

Using data for 64,177 Norwegian adults from the second wave of the Nord-Trøndelag Health Study (HUNT2), with linkage to the Norwegian Causes of Death Registry, we assessed all-cause mortality from survey participation in 1995 through to 2013. We used Cox proportional hazards models to examine mortality risk over 18 years associated with type 2 diabetes status and the presence of comorbid affective symptoms at baseline.

Three clear patterns emerged from our findings. First, mortality risk in individuals with diabetes increased in the presence of depression or anxiety, or both. Second, mortality risk was lowest for symptoms of anxiety, higher for comorbid depression-anxiety, and highest for depression. Lastly, excess mortality risk associated with depression and anxiety was observed in men with diabetes but not in women. The highest risk of death was observed in men with diabetes and symptoms of depression only (hazard ratio 3.47, 95% CI 1.96, 6.14).

This study provides evidence that symptoms of anxiety affect mortality risk in individuals with type 2 diabetes independently of symptoms of depression, in addition to attenuating the relationship between depressive symptoms and mortality in these individuals.