Can a diabetic person with High Blood Pressure be Vegan, and healthy?

Yes. A low-fat plant based diet has been proven to reverse high blood pressure and even type 2 diabetes. I suggest you watch the movie "Chow Down". Its about 3 people who, following Dr. Caldwell B. Esselstyn's advice, gave up all animal products. Two of them were suffering from high blood pressure and heart disease: both reversed. One was suffering from type 2 diabetes: her weight went down, she was reversing her diabetes UNTIL she decided that she didn't have time to prepare healthy meals anymore and switched back to eating animal products all the time.