OBJECTIVE -We examined the association between depression, measured as either a continuous symptom severity score or a clinical disorder variable, with self-care behaviors in type 2 diabetes.RESEARCH DESIGN AND METHODS -We surveyed 879 type 2 diabetic patients from two primary care clinics using the Harvard Department of Psychiatry/National Depression Screening Day Scale (HANDS), the Summary of Diabetes Self-Care Activities, and self-reported medication adherence.RESULTS -Of the patients, 19% met the criteria for probable major depression (HANDS score Ն9), and an additional 66.5% reported at least some depressive symptoms. After controlling for covariates, patients with probable major depression reported significantly fewer days' adherent to diet, exercise, and glucose self-monitoring regimens (P Ͻ 0.01) and 2.3-fold increased odds of missing medication doses in the previous week (95% CI 1.5-3.6, P Ͻ 0.001) compared with all other respondents. Continuous depressive symptom severity scores were better predictors of nonadherence to diet, exercise, and medications than categorically defined probable major depression. Major depression was a better predictor of glucose monitoring. Among the two-thirds of patients not meeting the criteria for major depression (HANDS score Ͻ9, n ϭ 709), increasing HANDS scores were incrementally associated with poorer self-care behaviors (P Ͻ 0.01).CONCLUSIONS -These findings challenge the conceptualization of depression as a categorical risk factor for nonadherence and suggest that even low levels of depressive symptomatology are associated with nonadherence to important aspects of diabetes self-care. Interventions aimed at alleviating depressive symptoms, which are quite common, could result in significant improvements in diabetes self-care.
Diabetes Care 30:2222-2227, 2007M ajor depression is a significant problem among patients with diabetes, with an estimated prevalence of 15-20%, compared with 2-9% in the general population (1). Among patients with type 2 diabetes, major depression is associated with a 2.3-fold increase in mortality, and minor or "subclinical" depression is associated with a 1.7-fold increase (2). Depression also increases the risk of poorer diabetes-specific outcomes such as hyperglycemia (3) and an increase in diabetes complications (4).The available literature suggests that clinically significant levels of depression are associated with a range of poorer selfcare behaviors including adherence to diet (5-8), exercise (6,7), and prescribed medications (5,7,9,10). However, although depression is clinically conceptualized as a discrete comorbid illness, few researchers have investigated the possibility of a dose-response relationship between symptoms of depression and poorer self-care, favoring instead a conceptualization of depression as a discrete comorbid illness when examining its relationship to diabetes self-care behaviors.The aim of the current study was to extend previous research by examining the relationships between depression and the full range of diab...