Is it true that people with Type 1 diabetes can eat as much sugar as they want as long as they are regulating it by taking insulin and monitoring it actively?

My friend is 22 and he has Type 1 diabetes. He eats a lot of cookies and junk food which is high in sugar. However he takes insulin before every meal and also makes sure that his blood sugar levels are normal. Is this okay or this is affecting his long term life? He also works out and has a bulky body (if that has to do anything with diet).