Hi there.. you can do gyming and exercises as that helps you reduce weight and reduce insulin resistance even, there is no contraindication for that, but avoid heavy exercises which are anaerobic exercises as they release lactic acid as end product of anaerobic metabolism which is not good if your on anti diabetic drugs like metformin.. to lose weight aerobic exercises help, heavy exercises infact add weight as they help in building more muscle mass which is needed for athletes, sportsmen..