Increasing evidence suggests that psychological disorders play an important role in the development and worsening of type 2 diabetes (T2D). Among the spectrum of psychological disorders, there is a wide literature about the association between depression and T2D and current data show an approximately two-fold prevalence of depression in adults affected by diabetes compared to un-affected subjects. Moreover, depression in diabetic patients is associated with higher blood glucose levels, poorer adherence to therapeutic regimens (whether pharmacological or therapeutic lifestyle changes), more medical complications, and higher hospitalization rates. Nevertheless, at the best of our knowledge, the mechanism underlying the association between depression and adverse diabetes-related outcomes is currently unresolved.