Is intermittent fasting safe if you have diabetes?

It requires medical supervision rather than being simply safe or unsafe. The specific risk is hypoglycaemia in anyone taking insulin or sulfonylureas, where doses usually need adjustment before changing eating patterns — this is not something to attempt without discussing it. For people managing type 2 diabetes with metformin or lifestyle alone, the risk is much lower and some find it a useful structure. What the evidence shows is that it works about as well as ordinary calorie restriction, so it offers a framework rather than a metabolic advantage. Monitor more frequently during any transition.