A Randomized, Placebo-Controlled Trial of Metformin for the Treatment of Overweight Induced by Antipsychotic Medication in Young People With Autism Spectrum Disorder: Open-Label Extension

Abstract

Objective: A previous study reported on a 16-week placebo-controlled, randomized clinical trial (RCT) of metformin for weight stabilization in 61 children and adolescents 6 to 17 years old with autism spectrum disorder who were prescribed atypical antipsychotics. The present study describes the results of a 16-week open-label extension.

Method: Fifty-two participants from the acute trial (85%) entered the extension; 22 had been on metformin during the initial RCT and 30 had been on placebo. Participants were re-titrated to 500 mg twice a day (6- to 9-year-olds) or 850 mg twice a day (10- to 17-year-olds) during the open-label extension. Primary outcome measure was change in body mass index (BMI) z-score after 16 weeks; secondary outcomes were change in additional body composition and metabolic parameters.

Results: After 16 weeks of open-label treatment, participants initially taking placebo during the RCT had lower BMI z-scores (mean 16-week change -0.10, p = .004). Statistically significant improvements also were noted in secondary body composition measures (weight z-score and BMI and weight percentile) but not in metabolic variables. Participants who initially had been taking metformin during the 16-week RCT maintained prior decreases in BMI z-scores but did not have additional weight loss. Three participants discontinued treatment because of an adverse event. No significant changes were noted on metabolic measures, although the decrease in hemoglobin A_1c was large (∼1 mmol) and consistent across the acute and open-label phases.

Conclusion: Metformin can be effective for decreasing weight gain associated with atypical antipsychotic use and maintaining prior improvement in children and adolescents with autism spectrum disorder. Clinical trial registration information-Treatment of Overweight Induced by Antipsychotic Medication in Young People With Autism Spectrum Disorders (ASD); http://clinicaltrials.gov/; NCT01825798.

Keywords: antipsychotic medication; autism spectrum disorder; metformin; weight gain.