How are diabetes and pre-diabetes diagnosed?

The following tests are used for diagnosis:

• A fasting plasma glucose test measures your blood glucose after you have gone at least 8 hours without eating. This test is used to detect diabetes or pre-diabetes.
• An oral glucose tolerance test measures your blood glucose after you have gone at least 8 hours without eating and 2 hours after you drink a glucose-containing beverage. This test can be used to diagnose diabetes or pre-diabetes.
• In a random plasma glucose test, your doctor checks your blood glucose without regard to when you ate your last meal. This test, along with an assessment of symptoms, is used to diagnose diabetes but not pre-diabetes.

Positive test results should be confirmed by repeating the fasting plasma glucose test or the oral glucose tolerance test on a different day.