Second-generation, or atypical, antipsychotic drugs have been increasingly used to treat mental-health problems in children in the U.S .over the last decade. They can help with cognitive deficits, mood disorders, impulse control and excitability, and, in some respects, have less side effects than older drugs. However, they are also associated with weight gain which can affect the body's ability to manage its blood sugar level - leading to diabetes - and also lead to heart disease. Lifestyle change (more exercise and a better diet) has been the preferred option to tackle these changes but a recent trial of a drug called metformin has shown promising results. The study of 39 children between the ages of 10 and 17 who were all taking antipsychotic drugs and whose weight had increased by at least 10% after a year of taking them compared one group taking metformin with another group taking a placebo. After 16 weeks the group taking metformin had stabilized their weight while the group taking the placebo were still putting on an average of a third of a kilogram a week. The placebo group also had more problems managing their blood sugar than the group taking metformin.
Klein, David J. ... [et al] - A randomized, double-blind, placebo-controlled trial of metformin treatment of weight gain associated with initation of atypical antipsychotic therapy in children and adolescents American Journal of Psychiatry 2006; 163: 2072-2079