Oral glucose tolerance test (OGTT)

A test that measures blood sugar levels after oral ingestion of a standard dose of glucose.



  • Eat normal food in the days leading up to this test (no diabetic or calorie-restricted foods).
  • Before the test, you will need to fast for at least 8 to 12 hours.
  • You may drink water, but coffee, cola or other drinks containing sugar or caffeine are definitely not allowed.
  • You may not perform any significant physical activity prior to the test. You will also need to rest for at least an hour before the test.
  • You may not smoke before or during the test.


Duration: 2 hours

You may not eat or smoke for the full duration of the test, and you must rest during this time. You will need to remain seated or lying down for two hours.

  • Blood draw at the start of the test.
  • You will drink a 75 g (200 ml) solution of glucose (sugar) within five minutes (time starts when the glass is empty).
  • After this, you will drink one cup of cold water.
  • Blood will be drawn 30 minutes, 1 hour and 2 hours after drinking. The blood sugar level is determined for these samples.


The oral glucose tolerance test is used to diagnose:

  • Diabetes and gestational diabetes in case of one deviating value
  • Acromegaly 
Oral glucose tolerance test (OGTT)
Last edit: 9 April 2024