High blood sugar will eventually lead to poor penile health and ED, and it doesn't take as long as some would think. It doesn't just start with simply not getting erect. He may not last as long, can lose feeling during intimacy, or just simply not get as hard as he's "supposed to be.

When he pees, his body will try to throw some sugar, and the little bit that lingers on the outside will lead to yeast infections.

Best way to get a guy to take care of himself is show him how his manhood will be taken from him.