How Is Diabetes or Pre-Diabetes Diagnosed?

The following tests are used for diagnosis:

• FPG (fasting plasma glucose) – measures your blood glucose after you have gone at
  least 8 hours without eating. The FPG is the preferred test for diagnosing diabetes due to
  convenience and is most reliable when done in the morning.
• OGTT (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, but is not performed regularly
  due to inconvenience.
• 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.