Efficacy of metformin for prevention of weight gain in psychiatric populations: a review

There is uncertainty with regard to the appropriate use of metformin for the prevention and management of second-generation antipsychotic-induced weight gain and metabolic abnormalities. We aim to systematically review the primary literature and to provide recommendations with regard to the use of metformin in psychiatric populations prescribed second-generation antipsychotics. The authors undertook a literature search of Medline, EMBASE, and PsycINFO using the search terms; antipsychotic OR atypical antipsychotic AND weight AND metformin. Narrative review was undertaken without additional statistical analysis. The search provided 198 results from which 10 original research papers were identified: six randomized controlled trials and one open-label study for adults and two randomized controlled trials and one open-label study for children and adolescents. Four meta-analyses were also identified. We concluded that if weight gain occurs after second-generation antipsychotic initiation, despite lifestyle intervention, metformin should be considered. Further studies with adequate statistical power are required to determine the efficacy of metformin in those with chronic psychotic illness.