For children and adolescents receiving antipsychotic medications for autism spectrum disorder (ASD), concomitant metformin may be able to reduce weight gain associated with these agents.

Researchers from the Holland Bloorview Kids Rehab Hospital, in Toronto, conducted a 16-week clinical trial assessing weight among 60 children and adolescents (average age 13) with ASD receiving atypical antipsychotics.

Twenty-eight patients were randomized to receive metformin and 32 to a placebo group. Changes in body mass index (BMI) z score – the studies primary outcome – showed that the metformin group had a greater reduction in weight gain, as assessed by change from baseline to week 16 BMI z scores (metformin vs. placebo difference of –0.10). Three (11%) participants in the metformin group had declines of 8–9% in BMI, among the other metformin patients none had a decline of greater than 5% over the 16 weeks. 

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While overall metformin was well tolerated, compared to placebo, participants in the metformin group experienced gastrointestinal adverse events during a higher percentage of treatment days.

The study’s authors highlighted the small sample size and period of time as limitations to their findings, however they concluded that, “These findings have important implications for children in whom the benefits of atypical antipsychotics for treating irritability and agitation symptoms are difficult to balance with the substantial weight gain that often accompanies their use.”

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