Here are a couple of things which will likely help you in terms of your blood flow issues. Gingko Biloba improves circulation. A couple of tests (I don't recall the websites now) were done in the past which showed 100% improvement in erection in 45 days time. Personally, I feel more alert (when I use Gingko) in just a few hours.
The other option, though you need to carefully monitor this one with diabetes, is L-Argnine. L-Argnine, like v1agra, operates on the principle of adding nitrogen-oxide to your blood system. You need this in order to produce an erection. Quantities required can range from 500mg up to 3000mg (3 grams). For optimum performance, take this half an hour to one hour before sexual activity.
Mixed nuts provide a good, natural source of L-Argnine as well.