Glucose Tolerance Test During Pregnancy
This leaflet will provide you with information about glucose tolerance test and why do you need to have it done during pregnancy.
What is Glucose Tolerance Test (GTT)?
A test that measures your body’s ability to process sugar (glucose).
Why do I need this test?
This test is done to detect if you have Gestational Diabetes Mellitus (GDM) which can develop during pregnancy. GDM occurs because your body cannot produce enough insulin (a hormone important in controlling blood glucose) to meet its extra needs in pregnancy. This results in high blood glucose levels.
When is this test done?
This test is usually done at 24-28 weeks (6-7 months), but can be done up to 32 weeks (8 months) of pregnancy. If you have had gestational diabetes in a previous pregnancy or at high risk of developing GDM, the test can be done earlier than 24 weeks.
How is this done?
Before the test:
- You will need to fast for a minimum 8 hours and a maximum of 10 hours before the test. You may drink water but avoid other beverages and chewing gum.
- Talk with your doctor about any medications you are taking such as metformin, corticosteroids, beta-blockers, diuretics and antidepressants that can affect the results.
- This test is also not ideal for you if you have had bariatric (weight loss) surgery within the last 2 years.
- When you arrive at the reception, please inform the staff that you have a GTT.
- The test usually takes up to 3 hours. Please bring something to read or an activity to keep you busy and please do not bring a child since this test takes a few hours.
- Please arrive on time.
During the test:
- While fasting, your health care provider will take a sample of blood from a vein in your arm to measure your fasting blood glucose level
- You will drink a sugary drink. If you are not able to tolerate the drink or if you vomit the solution, the test will not be done. Let your health care provider know if you feel dizzy, sick or nauseated
- Your health care provider will measure your blood glucose levels in 1 hour after the drink and then again after 2 hours
- You should not eat or drink prior to completion of 2 hour test
- After the completion of test, you will be offered a small snack box
- Your doctor or nurse will inform you about the results of the test