BACKGROUND:

Depression is common among patients with chronic medical illness. We explored the impact of depressive symptoms in primary care patients with diabetes on diabetes self-care, adherence to medication regimens, functioning, and health care costs.

METHODS:

We administered a questionnaire to 367 patients with types 1 and 2 diabetes from 2 health maintenance organization primary care clinics to obtain data on demographics, depressive symptoms, diabetes knowledge, functioning, and diabetes self-care. On the basis of automated data, we measured medical comorbidity, health care costs, glycosylated hemoglobin (HbA(1c)) levels, and oral hypoglycemic prescription refills. Using depressive symptom severity tertiles (low, medium, or high), we performed regression analyses to determine the impact of depressive symptoms on adherence to diabetes self-care and oral hypoglycemic regimens, HbA(1c) levels, functional impairment, and health care costs.

RESULTS:

Compared with patients in the low-severity depression symptom tertile, those in the medium- and high-severity tertiles were significantly less adherent to dietary recommendations. Patients in the high-severity tertile were significantly distinct from those in the low-severity tertile by having a higher percentage of days in nonadherence to oral hypoglycemic regimens (15% vs 7%); poorer physical and mental functioning; greater probability of having any emergency department, primary care, specialty care, medical inpatient, and mental health costs; and among users of health care within categories, higher primary (51% higher), ambulatory (75% higher), and total health care costs (86% higher).

CONCLUSIONS:

Depressive symptom severity is associated with poorer diet and medication regimen adherence, functional impairment, and higher health care costs in primary care diabetic patients. Further studies testing the effectiveness and cost-effectiveness of enhanced models of care of diabetic patients with depression are needed. Arch Intern Med. 2000;160:3278-3285.