Commentary

The combination of diabetes and depression confers a poor prognosis, and previous studies have suggested a bi-directional association between them. This report from the Nurses' Health Study confirms previous findings that diabetes is a risk factor for depression and that non-diabetic women with depression have a higher risk of developing type 2 diabetes. Although a study cohort of mostly White, professional women limits the generalisability of the findings, it would be surprising whether they were not relevant for men and other high-risk groups including ethnic minorities.

That the risk of depression in diabetic women was associated with oral antidiabetic agents and insulin is unsurprising as their use correlates with duration of diabetes and with diabetic complications. Depression may arise because of the burden of illness from complicated diabetes. The risk of developing diabetes in depressed women was independently associated with antidepressant therapy. Although there are other explanations, this study adds to growing evidence that long-term use of tricyclic and selective serotonin re-uptake inhibitor antidepressants causes weight gain and, probably as a consequence, increase the risk of type 2 diabetes.1 ,2

Patients with type 2 diabetes are at high risk for depression, yet there is still much to learn about how to diagnose and manage depression in this context. Therapeutic efforts targeted at mood disorder and diabetes are required, and collaborative approaches appear to be necessary.3 Further research into the metabolic side effects of long-term antidepressants is required, but their use should be accompanied by monitoring for weight gain and metabolic effects including diabetes.