I'm curious have you had your LH and testosterone levels checked recently? If these are low which I'm almost positive will be you should consider Clomid or HCG to treat this. I've recently been through all this but the good news is most doctors have no idea what they are talking about. You problem can almost certainly be fixed. Also, google raising Growth Hormone levels. Since you mentioned your a diabetic and this can happen as a result of your GH level being to low as well. So I'm almost positive your ED is related to that. Trust me I had to fight every doctor I went to to get my problems fixed but our body is designed to be able to heal itself.
There are few exercises for sexual disorders. I do not know whether they will apply to you or not. You may do further research on these exercises.. Do these exercises, only after consulting some expert. Google male deer exercise, kegel exercise, Anal peripheral prostate massage.
You may take a second opinion from another doctor. I do not know any thing about the venous leakage and hence cannot suggest any exercise with confidence.Be cautious.