KEYSTONE, COLO. — Depression is twice as common in diabetic adults as in the general population, William H. Polonsky, Ph.D., said at a conference on the management of diabetes in youth.
Moreover, coexistent depression and diabetes is associated with significantly greater all-cause mortality risk than either condition alone, hence the need to regularly screen adult diabetic patients for depression and to promote vigilance among patients and their families regarding its signs and symptoms, added Dr. Polonsky of the department of psychiatry at the University of California, San Diego, and president of the Behavioral Diabetes Institute, also in San Diego.
Multiple large epidemiologic studies indicate that at any given time, 17%–20% of adult diabetic patients meet diagnostic criteria for moderate to major depression, a rate up to twofold greater than that in adults overall.
South Carolina investigators recently studied the impact of depression and diabetes on all-cause and coronary heart disease mortality in 10,025 participants in the population-based National Health and Nutrition Examination Survey-I Epidemiologic Follow-Up Study.
During 8 years of follow-up there were 1,925 deaths, including 522 due to coronary heart disease. Compared with subjects who were nondiabetic and nondepressed, adjusted all-cause mortality was increased by 20% in those who had depression but not diabetes, by 88% in subjects with diabetes but not depression, and by 150% in participants with both diabetes and depression.
Coronary heart disease mortality was increased by 29% in individuals with baseline depression, by 126% in those with diabetes but not depression, and by 142% in subjects with both conditions (Diabetes Care 2005;28:1339–45).
Several studies also have shown threefold greater rates of new-onset coronary artery disease and retinopathy over a 10-year follow-up period in depressed diabetic patients compared with nondepressed diabetic patients, Dr. Polonsky said at the conference, sponsored by the University of Colorado and the Children's Diabetes Foundation at Denver.
Other studies have demonstrated that depression makes it tougher to initiate and maintain constructive behavioral change. In persons with diabetes, depression is associated with worse glycemic control as reflected in hemoglobin A1c levels 2.0%–3.3% higher than in nondepressed patients, along with an increased hospitalization rate, more lost work days, and greater functional disability. Screening diabetic patients regularly for depression is a simple matter even in a busy office practice.
Many screening questionnaires are available that patients can fill out in the waiting room. Or the physician can simply ask two straightforward questions:
▸ During the past month, have you felt down, depressed, or hopeless?
▸ Have you had no interest or pleasure in doing things?
A yes response to either screening question warrants further inquiry. By far the most widely used tool for this purpose in adults is the Patient Health Questionnaire-9. A Google search for “PHQ-9” will provide the scale itself for free, as well as the history of the test instrument, how to score the PHQ-9 properly, and other useful information.
Antidepressant therapy in diabetics is as effective as in nondiabetics. But if baseline glycemic control is good, antidepressant therapy will have little impact on diabetes-specific outcomes, Dr. Polonsky said.
That was shown in a preplanned subgroup analysis involving 417 depressed elderly patients with type 2 diabetes in the Improving Mood-Promoting Access to Collaborative Treatment (IMPACT) trial. This analysis compared usual antidepressant therapy in the primary care setting with enhanced care given in collaboration with a depression care manager who provided patient education, problem-solving treatment, and intensification of antidepressant medication as needed.
After 1 year, patients in the collaborative care arm were significantly less depressed and had better overall function than did those assigned to usual care; however, HbA1c values in the groups didn't differ (Ann. Intern. Med. 2004;140:1015–24).
Dr. Polonsky, who works chiefly with adults, said the data regarding depression in diabetic adolescents are more limited and equivocal. “It's not clear that their depression rates are as high as in adults,” he said.
Screening diabetic patients regularly for depression is a simple matter, even in a busy office practice. DR. POLONSKY
Other Factors in 'Diabetes Burnout'
Depression is just one contributor—albeit a major one—to the broader problem of diabetes-related emotional distress, also known as diabetes burnout, according to Dr. Polonsky.
Other major factors in diabetes burnout are harmful health beliefs, including a sense of powerlessness about the disease, crippling fear about the long-term complications, anger, frustration, and discouragement. Longitudinal studies suggest diabetes-related emotional distress results in poor glycemic control.
Diabetes burnout is common. In a recent study Dr. Polonsky conducted with roughly 300 adults with type 1 or 2 diabetes, 36% of those with type 1 and 21% of those with type 2 diabetes indicated that hopelessness about diabetic complications was a serious problem for them. Additionally, 19% of those with type 1 and 14% with type 2 disease indicated they felt unmotivated about diabetes self-care. And one-third of those with type 1 disease felt that diabetes controlled their lives; so did 14% with type 2 disease.