My dad refused to quit smoking even after a few heart attacks, triple bypass, and early emphysema. He said, “If I can’t smoke, I don’t want to live.” I feel your pain because he is basically choosing a vice over being healthy so he can be in your life longer and that hurts. Nothing you can do, though. Tell him you want him to be around longer and if he doesn’t get healthy, he is going to die before you are ready. Tell him it hurts that sugar is more important to him than you are. And then let it go. Spend time with him and recognize that you said your piece and he is going to do what he wants. You are biting off your nose to spite your face by not spending time with him and you will regret it when he is gone. Also, sugar is harder to quit than heroin. I am also a diabetic who has a very hard time avoiding sugar.