In general, you need to listen to your
regularRegular insulin doctor. On the other hand, I would never do anything consequential without a second opinion BY AN EXAMINING doctor. While Viagra has proved extremely safe for most men- you are now in a situation where you are having several medications and you need someone who can tell you if there are interaction effects.
One thing you might ask your doctor. Some men find Viagra effective on half a pill. You might ask your doctor if this would be the safest course of action for you. You definitely need on an site doctor, however, to give you sound advice.