You need to talk to your doctor as its one of the contra-indications in the terms and conditions of exante, assumedly can be dangerous for certain diabetics. (think it says type 1's and people taking insulin)
As far as I know, type 2 diet controlled should have no problems, and like SL says, it will definitely help and with the weight going it *can* drastically improve and even cure it (assuming you go to proper healthy eating afterwards of course)
Your blood sugar levels will fall very low on Exante, that's why some people feel dizzy and tired. And its more of a risk for a diabetic who's likely to have risky side effects from low blood sugars.
Regardless of which you have, if you are concerned, talk to your doc. x