Background: Early studies had suggested that depression is strongly and robustly associated with incidence of diabetes. It has been hypothesised that diabetes may increase the risk of depression, but there has been no evidence-based clinical evaluation of this hypothesis.
Objectives:We therefore examined the overall clinical research evidence to show whether the hypothesis is true.
Methods:We conducted a search using PubMed, Cochrane Library and 4 Chinese electronic databases for publications till January 2017. Reviewers assessed the eligibility of each study by exposure/outcome measurement and study design. Only case-control/cohort studies of depression and diabetes that excluded prevalent cases of depression (for diabetes predicting depression) were included. The methodological quality of studies was evaluated by the risk-of-bias tool quality of NOS (NewCastle-Ottawa Quality Assessment Scale)/CASP (Critical Skills Appraisal Programme).
Results:Seventeen clinical studies were identified published till January 2017,including 4 cohort studies, 2 case-control studies and 11 cross-sectional studies. These studies included a wide spectrum of diabetes including Gestational diabetes mellitus, Elderly diabetes and Type-2 diabetes. All 4 cohort studies showed that the diabetes-depression association is bidirectional. Two cohort studies and 2 cross-sectional studies showed that patients with Gestational diabetes mellitus had more probability of being diagnosed with depression.Two case-control studies and two cross-sectional studies showed that diagnosed diabetes was associated with increased risk of developing elevated depressive symptoms. Some another studies showed that depressive symptoms in patients with diabetes were associated with some factors, like age, gender, marital status and education.
Conclusions:Our results showed that diabetes mellitus can increase the risk of serious outcomes of depression, such as suicide and hospitalisation, and future research should focus on identifying mechanisms linking these conditions.