A fasting glucose test that shows over 126 milligrams per deciliter of blood sugar, an oral glucose tolerance test of over 200 milligrams per deciliter and a random blood sugar test of over 200 milligrams per deciliter can all indicate diabetes, notes WebMD. The tests are conducted in different circumstances.
The fasting test is measured after 8 hours without eating, states WebMD. An oral glucose tolerance test involves consuming sugar before the blood sugar test is administered. For the random check to be part of a valid diagnosis, it is accompanied by other signs of diabetes, such as problems with hydration.