Type 2 diabetes and depression can be a fatal mix. Patients whose type 2 diabetes was accompanied by minor or major depression had higher mortality rates, compared to patients with type 2 diabetes alone, over the three-year period of a recent study in Washington state.
The results appear in the November 2005 edition of Diabetes Care, published by the American Diabetes Association.
Researchers at the University of Washington (UW) and at Group Health Cooperative, a large, Seattle-based health plan, conducted the study. The researchers surveyed and followed up 4,154 patients with type 2 diabetes. The patients filled out written questionnaires. With patients' consent, automated diagnostic, laboratory, and pharmacy data were collected from the HMO. The researchers also reviewed Washington state mortality data to analyze diabetes complications and deaths.
Depression is common among people who have type 2 diabetes. This high prevalence can have unfortunate repercussions. Both minor and major depression among people with diabetes are strongly linked with increased mortality.
"Depression may be associated with increased mortality in patients with diabetes because of both behavioral and biologic factors," the researchers noted in their article. More work, they added, is needed to untangle the cause-and-effect relationships among depression, behavior, diabetes complications, and mortality.
Dr. Wayne Katon, professor and vice chair of the UW Department of Psychiatry and Behavioral Sciences, led the recent study. He is a noted researcher on the associations between depression, aging, and chronic diseases, and on the medical costs and personal toll from untreated or inadequately treated depression. The research team included Drs. Carolyn Rutter, Greg Simon, Elizabeth Lin, Evette Ludman, and Michael Von Korff from the Group Health Cooperative Center for Health Studies; Dr. Paul Ciechanowski, UW assistant professor of psychiatry and behavioral sciences; Dr. Leslie Kinder from the Veterans Affairs Puget Sound Health Care System; and Dr. Bessie Young from the UW Department of Medicine.
Previous studies by Katon's research group have shown that patients with depression and diabetes are less likely to follow diet and exercise guidelines or to check their blood glucose levels, and to have more lapses in filling their prescriptions for oral hypoglycemic, lipid-lowering, and high blood pressure medications. People with depression and diabetes were also more likely to have three or more heart disease risk factors, such as smoking, obesity, and a sedentary lifestyle, compared to people with diabetes alone.
Patients with both depression and diabetes are also significantly more likely to have cardiovascular and cerebrovascular complications. Depression may increase complications, not only because of poor self-care, but possibly through the brain chemistry and nervous system abnormalities that accompany depression, the researchers noted. They added that people may also become depressed in response to changes in their ability to function or because of physical symptoms, such as chronic pain from nerves damaged by diabetes.