The objective of this study was to examine the strength and consistency of the relationship between depression and diabetes complications in studies of type 1 and type 2 adult patients with diabetes.
MEDLINE and PsycINFO databases were searched for articles examining depression and diabetes complications in type 1 and type 2 diabetes samples published between 1975 and 1999. Meta-analytic procedures were used. Studies were reviewed for diabetes type, sample size, statistical tests, and measures of diabetes complications and depression. Significance values, weighted effect sizes r, 95% confidence intervals (CI), and tests of homogeneity of variance were calculated for the overall sample (k = 27) and for subsets of interest.
A total of 27 studies (total combined N = 5374) met the inclusion criteria. A significant association was found between depression and complications of diabetes (p < .00001, z = 5.94). A moderate and significant weighted effect size (r = 0.25; 95% CI: 0.22–0.28) was calculated for all studies reporting sufficient data (k = 22). Depression was significantly associated with a variety of diabetes complications (diabetic retinopathy, nephropathy, neuropathy, macrovascular complications, and sexual dysfunction). Effect sizes were in the small to moderate range (r = 0.17 to 0.32).
These findings demonstrate a significant and consistent association of diabetes complications and depressive symptoms. Prospective, longitudinal studies are needed to identify the pathways that mediate this association.
From the Departments of Medicine (MdG., R.E.C.) and Psychiatry (MdG., R.A., K.E.F., R.E.C., P.J.L.), Washington University School of Medicine, St. Louis, Missouri.
Address reprint requests to: Mary de Groot, PhD, Washington University, Division of Health Behavior Research, Campus Box 8504, 4444 Forest Park, Ste 6700, St. Louis, MO 63108. Email: email@example.com
Received for publication July 13, 2000; revision received November 27, 2000.