The Diagnosis of Diabetes
How is Diabetes Diagnosed?

Diabetes is diagnosed with blood tests. There are two main tests which are used. The simplest is called a fasting blood sugar or FBS. Two FBS tests on different occasions are required to make the diagnosis of type 2 diabetes. The other test is called an oral glucose tolerance test or OGTT. It takes a little more time (two hours), but only one test is usually required.

A fasting blood sugar (FBS)

  • A sample of blood is drawnusually early in the morningbefore any food or drink is taken (except water)
  • The test examines the concentration of sugar (glucose) present in the blood
  • 126 mg/dl or higher indicates diabetes
  • The test should be repeated on a second occasion to confirm the result
Oral glucose tolerance test (OGTT)
  • A fasting blood sugar test is done first, then
  • A concentrated sugar drink is given
  • Exactly 2 hours after the sugar drink, another blood sample is drawn to check the concentration of sugar (glucose) in the blood.
OGTT results
  • One has diabetes if OGTT result after 2 hours is at or above 200 mg/dl
  • mg/dl means milligram per deciliter
  • mg/dl is a unit of measurement used to measure blood glucose concentration.

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