Effects of metformin on weight loss and metabolic control in obese patients with schizophrenia and schizoaffective disorder: a randomized, double-blind, controlled clinical trial

Abstract Objective: The effect of metformin on weight changes and some metabolic parameters in patients with schizophrenia and schizoaffective disorder was investigated in this study. Methods:  This study, performed during 2018-2019, was a randomized, double-blind, controlled clinical trial. A total of 66 obese patients (BMI≥27) with schizophrenia and schizoaffective disorder, hospitalized in the departments of Razi Psychiatric Hospital, after completing the informed consent form, entered the study and randomly divided into intervention and control groups. The patients received metformin or placebo for 12 weeks. The dose of metformin was gradually increased, and, in case of patient’s tolerance, was prescribed up to 500 mg twice daily. During the study, all patients received their previous therapies. The variables included BMI, weight, waist circumference, lipid profile and fasting blood glucose, which were studied at the beginning of the study and at weeks 4, 8, and 12. Data were analyzed using a post hoc test by SPSS software. Results: The results showed a significant decrease in weight (3.5 kg) and BMI (1.30) at the end of the week 12, and there was a significant reduction in waist circumference (5.9 cm) at the end of the week 8, compared to the placebo group (P <0.05). Moreover, metformin had no significant effect on fasting blood glucose and lipid profile in comparison with the placebo group. Conclusion: Based on the findings of this study, metformin by reducing the weight, waist circumference, and BMI can have a significant role in decreasing the complications of obesity and metabolic disorders in patients with schizophrenia and schizoaffective disorder; Therefore, given that the complications of metformin are low and transient, it can be recommended as a safe and tolerable drug in obese patients having schizoaffective disorder and schizophrenia. Keywords: Schizophrenia, schizoaffective disorder, obesity, metformin, antipsychotics.