Association between obesity and depression in patients with diabetes mellitus type 2; a study protocol

Background: Diabetes mellitus and depression are highly prevalent conditions throughout the world and have significant impact on health outcomes. It has been estimated that diabetes mellitus type 2 affects about 246 million people in the world; nevertheless, incidence varies among countries. There is evidence that depression is associated with a poor metabolic control in patients with type 2 diabetes mellitus that present other health problems (such as hypertension and obesity). The aim of this study protocol is to determine if obesity increases the risk for depression in patient with diabetes type 2.

Methods: The analysis will be reported following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA).The studies suitable for inclusion will be assessed by the Newcastle-Ottawa Scale (NOS) to determine their methodological quality. To identify the studies of interest, we will search on PubMed and EBSCO databases. We will use the following keyword combinations: "Diabetes Mellitus type 2 AND obesity AND depression", "depression AND Diabetes Mellitus type 2", "Diabetes Mellitus type 2 AND body mass index cross sectional study", "depression AND obesity cross-sectional study". Causes for exclusion will be publications that studied patients diagnosed with diabetes mellitus type 1; articles that focused on the treatment and complications of diabetes mellitus type 2; publications that have studied other clinical or psychiatric conditions (for instance, seizure disorder or history of schizophrenia, bipolar disorder, psychotic symptoms or dementia).

Conclusion: The results of this study will form the basis for a better understanding of the association between obesity and depression in patients with diabetes mellitus type 2, and will allow development of prediction tools and better interventions. It is evident that several modifiable and non-modifiable risk factors play an important role in the pathogenesis of diabetes among population. Currently, evidence for the deleterious effects of diabetes mellitus type 2 are based on cross-sectional or other observational designs. Therefore, this study will have important implications for future research and public health guidance.