Pathophysiological mechanisms involved in the relationship between diabetes and major depressive disorder

Diabetes mellitus (DM) and major depressive disorder (MDD) are diseases that are expanding globally. Separately, each presents with several comorbidities for patients. When the two diseases present simultaneously in the same subject, there is a drastic worsening in the quality of life of the patient. This study reviewed the literature relating to the relationship between MDD and DM, bringing forward studies showing that DM develops due to MDD, and others that report the opposite. According to the studies reviewed, DM and MDD are both debilitating conditions that are associated with significant morbidity, mortality, and healthcare costs. When these two diseases coexist, the association results in a decreased adherence to treatment, poor metabolic control, higher rates of complications, a decrease in the quality of life for the patient, increased healthcare use and cost, increased disability and lost productivity, and an increased risk of death. Therefore, it becomes essential that there are larger studies targeting the association of these two diseases, as for the patient, preventing even one of them will ensure improvements in their quality of life.