A review of the relationship between depression and diabetes in adults: is there a link?

OBJECTIVE: To review the support for two hypotheses concerning the interrelationship between depression and diabetes and to identify areas in which more research is needed. RESEARCH DESIGN AND METHODS: A review was conducted using primarily electronic databases. Articles relating to diabetes and depressive symptomatology, depressive disorder, and dysthymic disorder were selected. The study focuses mainly on adults with diabetes. RESULTS: The initial onset of major depressive disorder (MDD) seems to be independent of the onset of type 2 diabetes, but results remain equivocal for type 1 diabetes. However, in both type 1 and type 2 diabetes, diabetes-related psychological and physiological processes may be involved in the higher recurrence and longer duration of MDD and depressive symptomatology CONCLUSIONS: The hypotheses that the initial occurrence of clinically significant depression, MDD, results from either biochemical changes directly due to type 2 diabetes or its treatment or from the psychosocial demands imposed by the illness or its treatment do not seem to be supported. MDD in diabetic individuals represents a multidetermined phenomenon resulting from interactions between biologic and psychosocial factors. This interaction may increase the probability of developing type 2 diabetes in otherwise healthy individuals.