Objectives: To identify factors independently associated with depression in Japanese patients with diabetes, after controlling for potential confounding factors.
Methods: Among 197 outpatients with diabetes, 129 (type 1: 24, type 2: 105) completed a questionnaire concerning socio-demographic and health-related variables. Depression screening was done using Zung's Self-Rating Depression Scale test, followed by diagnostic interviews by experienced psychiatrists employing the Diagnostic Statistical Manual of Mental Disorders, 4th edition (DSM-IV).
Results: Forty-seven patients (36.4%) had symptomatological depression. A Self-Rating Depression Scale cut-off score of 40 had good sensitivity (100%) and modest specificity (59%) for detecting major depressive episode, in accordance with the DSM-IV. Diabetic patients suffering from depression were more likely to have neuropathy, retinopathy, body pain, a feeling of poor general health, and lack of social support, than the non-depressed patients. However, age, gender, marital status, diabetes type, insulin requirement, duration of diabetes, hemoglobin A1c (HbA1c) and the presence of nephropathy did not differ between the two groups. In multivariate logistic regression analysis, body pain (OR 3.26, 95% CI 1.31-8.08) and the presence of microvascular complications (OR 2.81, 95% CI 1.13-6.98) were independent factors associated with depression. Specifically, diabetic neuropathy (OR 3.10, 95% CI 1.17-8.22) was associated with depression independently of age, gender, marital status, social supports, quality of life, diabetes type, duration of diabetes, HbA1c, and insulin requirement.
Conclusions: A diabetic complication, specifically neuropathy, was independently associated with depression in patients with diabetes. The present findings indicate the need to find a biological base common to both depression in diabetes and diabetic neuropathy.