What the best diagnose for pre diabetes? is regular blood test should be reliable enough?

4 ways: Hi. Testing for diabetes can be done 4 ways: fasting serum glucose, 2-hour 75 gram oral glucose tolerance test, A1c, and random (non-fasting) serum glucose. Each has it's own diagnostic criteria, and the fasting glucose, A1c, and 2-hour post-challenge glucose also have intermediate criteria (i.e., prediabetes). Serum glucose must be used for diagnosis (i.e., NOT finger stick blood glucose).