Depression is a severe medical illness that can interfere with an individuals self-care behaviors. Depression is prevalent , burdensome , treatable , and costly . Recognizing depression in diabetic individuals is critical because depression may play a role in worse control of diabetes and worse diabetes outcomes [5-10]. Depression also appears to increase the costs associated with treating diabetes . A number of clinical trials have recently focused on whether treatment of depression can lead to improved diabetes outcomes [12-15]. In this review, we examine the present state of knowledge on the interaction of depression and diabetes, discuss the epidemiologic and physiologic evidence for the co-occurrence of these conditions, and describe the ways in which diabetes control is worsened by depression, how depression interferes with diabetes care, and how depression acts to increase costs in diabetics. We focus specifically on interventions to treat depression in patients with diabetes and suggest areas of future research and practice with respect to improving care and outcomes those suffering in the intersection of these diseases.