Diabetes can be diagnosed with a blood test that measures the level of sugar (glucose) in the blood. Two different blood tests are available. One is called a "fasting plasma glucose" or FPG, which is the blood sugar level measured after fasting for eight hours.
Another test (the "2-hour plasma glucose" or 2-hr PG) measures blood sugar two hours after drinking a special sugar mixture.Test results are as follows:
Diabetes can also be diagnosed if a patient has diabetes symptoms and a random blood sugar is 200 mg/dl or above (11.1 mmol/L or higher).
Errors can occur when screening for diabetes, and blood tests should be repeated at least once before the diagnosis is made.