Aim: To conduct a systematic literature review in order to estimate the prevalence and odds ratio of clinically relevant depression in adults with Type 2 diabetes compared with those without.
Methods: MEDLINE, EMBASE and PSYCINFO databases were searched using MeSH terms and free text to identify relevant controlled studies. Published reference lists were also examined. Study selection and appraisal were conducted independently by two reviewers and a meta-analysis was performed to synthesize and analyse the data.
Results: Ten controlled studies including a total of 51 331 people were published between January 1980 and May 2005. The prevalence of depression was significantly higher in patients with Type 2 diabetes compared with those without [17.6 vs. 9.8%, OR = 1.6, 95%, confidence interval (CI) 1.2-2.0]. However, in most studies, patients with diabetes differed from those without on variables known to be associated with an increased risk of depression. The prevalence of depression was higher in females with diabetes (23.8%) compared with males (12.8%); however, the odds ratio for depression in patients with Type 2 diabetes compared with those without was higher in males (OR = 1.9, 95% CI 1.7-2.1) than females (OR = 1.3, 95% CI 1.2-1.4). Failure to report potential confounders prevented a more rigorous meta-analysis of risk.
Conclusion: We identified raised rates of depression in people with Type 2 diabetes, however, there is a need for well-controlled and better-reported studies to inform the development of effective treatments for depression in these patients.