Metformin treatment improves depressive symptoms associated with type 2 diabetes: A 24-week longitudinal study

Objective: Metformin is a medication that is widely used for lowering blood sugar in patients with type 2 diabetes. Metformin was shown to have significant antidepressant effects; however, it is not clear whether metformin treatment improves outcomes in patients with type 2 diabetes who have concomitant depressive symptoms. Methods: A total of 475 patients with type 2 diabetes mellitus with depressive symptoms were included in this study and divided into metformin and nonmetformin groups according to whether they were taking metformin. The DASS-21 was used to assess patients' depression and anxiety scores before and after a 24-week intervention. In addition, general information about whether the patients had developed complications from diabetes and whether they had been diagnosed with other diseases was assessed. Results: (1) After 24 weeks, anxiety and depression scores were significantly lower in the metformin group than in the nonmetformin group. (2) The prevalence of depressive symptoms was significantly greater in female type 2 diabetic patients than in male patients (OR = 2.039, 95 % CI = 1.160-3.568). (3) People with type 2 diabetes who develop complications from diabetes (OR = 1.794, 95 % CI = 1.015-3.171) and those diagnosed with other conditions are more likely to experience depressive symptoms. Conclusion: Metformin has an ameliorative effect on type 2 diabetes. However, women, those with diabetes complications, and those with type 2 diabetes who are also diagnosed with other conditions are more likely to experience depressive symptoms.