Diabetes and incident depression: Is the association mediated or modified by sociodemographic factors or co-morbidities? A systematic review.

OBJECTIVE: Diabetic patients suffer more frequently from depression. Aim was to evaluate sociodemographic parameters and co-morbidities and late complications as potential modifying factors in the occurrence of depression in diabetic individuals. RESEARCH DESIGN AND METHODS: We performed a systematic review, based on established meta-analyses and additional original publications in 2005-2009 in Medline and PsycINFO. We included articles focusing on longitudinal studies which evaluated the appearance of depression in diabetic and non diabetic individuals and further analyzed interactions or separate additional influences of potential modifying factors. RESULTS: 8 eligible studies were identified. 6 studies were population based. Only 3 studies analyzed the interaction between the variables of interest and diabetes on the incidence of depression. Remaining used diverse other methods to control for associated factors. The strongest influence was found for a general measure of co-morbidities but this influence was ambiguous. No significant modifying effect or interaction was found for sociodemographic factors. CONCLUSION: There seems to be a clear need for more research concerning mediating and modifying factors or a more stringent presentation of results in order to identify groups at risk or to identify treatment strategies.