Diabetes is pretty easy to test for. So if it came up negative I wouldn't worry, at least for now. If you know someone who is diabetic, he or she will probably have a glucometer (blood sugar meter) and probably would be happy to test you from time to time. High blood sugar can be caused by many things besides diabetes, but normal blood sugar means you definitely don't have it.
In fact if you're a constant worrier, you can get a glucometer for about $10 on EBay, and the strips are about 50 cents each. You could test yourself once a month or so just to be sure.
