Unfortunately, the early teen years are a stage of life where diabetes can pop up even if not on
Risperdal. I was diagnosed when almost 13, and this is a common age to see the beginnings
of diabetes. So do get him tested. If he has gained a lot of weight (above what is considered normal), a switch to another medication may help, and losing the excess weight may help bring the glucose levels down. In any event, once you have results on the tests, I hope his doctor will have a good plan of action.