Requirements Prior to the Test
- You are to remain on a normal, unrestricted diet for at least 3 days prior to test.
- You have had no acute significant illness for 2 weeks prior to test.
- Fasting is required for a period of 8-10 hours prior to the test. (No food or fluids such as tea, coffee or fruit juice.) You may have sips of water if you are thirsty.
- Due to the nature of the test, testing is generally done in the morning.
- Maintain normal activity prior to the test.
- Bring a list of any current medications with you to the collection centre.
- Avoid smoking for one hour before and during test.
- Before drinking the glucose, please inform the collection staff if you have any allergies.
What to do during the procedure
- You must remain seated quietly for 30 minutes before and during the test.
- You will be at the collection centre for a minimum of 2 hours and 45 minutes.
- You are required to remain in the collection centre until the procedure is completed.
- Bring some reading material or other activity to pass the time.
- If you feel unwell during the test, please inform the collection staff as you may wish to lie down.
What the Procedure involves
- A fasting blood sample collected.
- A 75g bottle of glucose to drink within 5 minutes.
- A 1 hour post glucose blood sample collected.
- A 2 hour post glucose blood sample collected.
If insulin levels are requested with the GTT, the collection staff will take blood for this in a separate tube, at the same time each glucose blood sample is collected.
Your Doctor may have ordered an extended GTT test which will require a commitment of 5 hours.