A total of 2759 patients with diabetes enrolled in a large HMO were
followed over a 5-year period. Patients filled out a baseline mail survey and participated in a telephone
interview 5 years later. Depression was measured with the Patient Health Questionnaire (PHQ-9) and
diabetes self-care was measured with the Summary of Diabetes Self-Care Activities (SDSCA) questionnaire.
Baseline and longitudinal evidence of diabetes and medical disease severity and complications
were measured using ICD-9 and CPT codes and verified by chart review.