How to get rid of Belly Fat while a type 2 Diabetic?

I have been a type 2 Diabetic for almost 2 years. I "handle" my sugar by diet and with Metformin. I have have or use to have most of the symptoms of metabolic syndrome and I weigh 280 lbs.  I am trying without any success to reduce my belly fat. before the Diabetes hit, I could swim and do crunchs on my abominitizer and the belly fat would subside. Now, I am losing only a small amount of weight, a 1l a week, after doing 1 to 2 hours of exercise a day, 7 days/week, and it is coming off everywhere but my belly. Is there any foods I should avoid? Is there an foods I should try that will encourage a drop in belly fat? Are there any exercises I can do that will encourage a drop in bell fat?