[Comment] Metformin: translating the evidence for prevention of weight gain

Melissa DelBello and colleagues1 should be commended on their clinical trial evaluating the effectiveness of metformin in mitigating weight gain in young people with bipolar disorder and related mood disorders taking second-generation antipsychotics. This clinical trial has many merits, including being sufficiently powered, and focusing on children and adolescents who are often neglected in clinical trials but are more prone to metabolic side effects. Furthermore, the trial had a long follow-up period of 2 years and examined the efficacy of an agent that is long off patent.