So in diagnosing diabetes, doctors measure glucose in the blood. Urine tests are a very useful way to measure ketones, substances that build up when blood glucose is very high. The goal of blood glucose tests is to find out whether you have a very large amount of glucose in your blood. Screening tests are performed on people who have no symptoms of diabetes. On the other hand, diagnostic tests are done to confirm a diagnosis that is already suspected from the patient's symptoms.
Screening tests are fast, easy to perform, and cheap.
Screening tests require as little as a drop of blood from your fingertip and take only a minute or two to complete. Most doctors don't screen everyone for diabetes during regular checkups. The chance of finding the disease in most people is just too low. But screening tests are useful for people who may be at risk for developing diabetes. If you are 45 years or older, have your blood glucose level checked every 3 years.