However, if he is exercising, then he can get away with eating something like a whole fruit right before exercising (depending on his glucose level) beforehand and the cardio exercise will even it out. There is a
Diabetic Exchange
Diet that is
in books where they assign you certain amount of meat, bread amounts that you can have at each meal - or trade off a lean meat for a little more fat, etc. so you don't have to count calories.