Oral Glucose Tolerance Test During Pregnancy


What is an oral glucose challenge test?

The oral glucose challenge test is performed to screen for gestational diabetes.

When is the oral glucose challenge test performed?

Gestational diabetes is generally diagnosed between the 24th and 28th week of pregnancy. If you have had gestational diabetes in a previous pregnancy, or if your healthcare provider is concerned about your risk of developing gestational diabetes, the test might be performed earlier.

Test Details

What can I expect on the day of the test?

On the day of the test, please follow instructions given to you by your healthcare provider or the lab (if applicable).

This test involves quickly (within five minutes) drinking a sweetened liquid (called Glucola), which contains 50 grams of glucose. A blood sample is taken from a vein in your arm about 60 minutes after drinking the solution. The blood test measures how the glucose solution was processed by the body.

Normal blood glucose levels peak within 30 to 60 minutes after drinking the glucose solution. A higher than normal blood glucose level does not always mean you have gestational diabetes.

General guidelines: You may eat a light breakfast on the day of the test, avoiding items with high sugar content, such as orange juice, pancakes, and doughnuts. Report to your specified location for the Glucola drink. After drinking Glucola, do not ingest any food or drink and do not smoke until your blood is drawn, one hour later. This can be done at the time of one of your prenatal visits.

Further diagnostic test

If your healthcare provider determines your blood glucose level was elevated, you will have an additional gestational diabetes screening test. If this test is indicated, your healthcare provider will provide you with information.

Last reviewed by a Cleveland Clinic medical professional on 01/01/2018.


  • American Pregnancy Association. Glucose tolerance test. (http://americanpregnancy.org/prenatal-testing/glucose-tolerence-test/) Accessed 10/4/2018.
  • American Diabetes Association. Diagnosing diabetes and learning about prediabetes. (http://www.diabetes.org/diabetes-basics/diagnosis/) Accessed 10/4/2018.
  • American Association for Clinical Chemistry. Lab Tests Online: Glucose tests. (https://labtestsonline.org/understanding/analytes/glucose/tab/test) Accessed 10/4/2018.

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