My son is 11. He is obese. Despite healthy food and substantial exercise he is unable to lose weight and is having problems with his self esteem. We went to a paediatric endocrinologist who advised diet and exercise. We tried hard for 6 months. Nothing is working. Our family physician advises to start metformin. We also want to do that. He has dark pigmentation around his neck acanthica nigricans but his insulin resistance levels have not yet crossed borderline. We want to start him on metformin. Is that ok ?