Are you claiming that increased sexual activity improves ED? When I was young I could climax repeatedly. Now, I feel like I need to conserve my "vital energy" or whatever, or I will dissipate it. Regarding diabetes, although I'm thin, I'm practically a fruitarian and eat a lot of fructose.
Yes, in general, that will be true. Orgasms increase key neurotransmitters, exercise the pelvic floor muscles, increase testosterone and on and on.
Now, that said, every guy has to find the balance point. Some men will probably do better with an O every two days, some every day and some 2 X/day. There's no formula for that I'm afraid.
As always, more is not always better. You don't want to cross your natural refractory point. But guys who site around and don't orgasm for a week and "let things go" - I think they'll find this is a big mistake.
Hope that makes sense...