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.