Glucose Challenge Test
What is a glucose tolerance test?
This is a test to see how your body handles sugar during pregnancy or to screen for gestational
diabetes. You do not need to follow a special diet before the test. Eat normally, but avoid
eating or smoking just before or while you are drinking the glucose solution.
When is the glucose tolerance test done?
Gestational diabetes is most often diagnosed between 24 – 28 weeks of your pregnancy. During
this time, insulin resistance can start. If the result of your one-hour test is abnormal, you may be
given a second test on another day. This test with will measure your blood sugar over a three-
If you have had gestational diabetes with a previous pregnancy or other risk factors, your
provider may order this test earlier in your pregnancy.
How is the test done?
Arrive at the clinic lab about 10 minutes before your test. You will be given a bottle of a
sweetened solution called Glucola® to drink. This drink causes a rise in your blood sugar level.
An hour after drinking the solution, you will have your blood drawn to check your blood sugar.
The blood test measures how your body handled or processed the glucose solution.
When will I get my results?
Results are most often available in a day or so after your blood draw. Your provider will review
your test results with you by phone or in the clinic. A test result of less than 140 is a normal
What if the result of my glucose screen is abnormal?
If your blood glucose level is 140 or higher, you will need to have another glucose test done.
This is a three-hour glucose test.
You will be asked not to eat or drink anything after 10:00PM the evening before your second
When you arrive, the lab tech will first draw your blood to check your fasting blood sugar. After
this, you will be given the glucose to drink. This amount will be twice as concentrated as when
you did the test the first time.
Your blood will be drawn again at 1 hour, 2 hours, and 3 hours after drinking the solution. Bring
something to read or do as you will be asked to stay in the lab area.
If two of the lab results are abnormal, you may be referred to a specialist. The specialist will
help us decide how best to manage your blood sugars during the rest of your pregnancy. Your
provider will speak with you about this.
It is important that you ask questions or discuss your concerns with your providers.
*If two or more of the lab results are abnormal, you will be referred to a diabetic educator and
nutritionist. They will teach you how to manage your diet and exercise and how to check your
blood glucose levels throughout the remainder of your pregnancy. Your provider will speak with
you further about this.
Your health care team may have given you this information as part of your care. If so, please use it and call if you
have any questions. If this information was not given to you as part of your care, please check with your doctor.
This is not medical advice. This is not to be used for diagnosis or treatment of any medical condition. Because
each person’s health needs are different, you should talk with your doctor or others on your health care team
when using this information. If you have an emergency, please call 911. Copyright © 3/2015 University of
Wisconsin Hospitals and Clinics Authority. All rights reserved. Produced by the Department of Nursing. HF#6049