Fasting blood sugar test: measures your blood sugar level after an overnight fast (don't eat). How can you tell if you have diabetes? Most of the initial symptoms are due to higher than normal levels of glucose, a type of sugar, in the blood. The diagnosis of diabetes is always confirmed by laboratory results. You'll usually get your blood test results within a few days.
If you have symptoms that came on quickly and brought you to the hospital, the results should appear within an hour or two. Your doctor can diagnose diabetes, prediabetes, and gestational diabetes using blood tests. Blood tests show if your blood glucose level, also called blood sugar, is above the range that is healthy for you. Blood tests can also help identify the type of diabetes you have.
If you're being tested for type 1 diabetes, they'll do more blood tests to check your blood ketone levels. A nurse will draw some blood from a vein in your arm and check your blood glucose levels.