The Glucose Tolerance Test – what to expect

18 November 2022

The Glucose Tolerance Test (GTT) measures how well your body uses glucose (sugar). Testing is usually performed first thing in the morning after a 10-hour fasting and resting period.

Exercise, smoking and drinking alcohol should be avoided during both the fasting period and during the test.

In the week before your test, you do not have to change your eating patterns or stop taking your normal medications.

Bookings are required for GTTs, and the test takes about 2 ½ hours – make sure you bring a good book or maybe binge your favourite show! For your comfort, we also recommend you wear comfy clothes.

On the day:

• Remember to drink several glasses of water to prevent dehydration.
• A blood sample will be collected on your arrival.
• You will then be asked to drink a glucose solution within 10 minutes, after which more blood samples will be collected for testing.
• You can only drink water during the test.

You cannot leave the collection centre during the test.

It’s important that you advise us if you have had weight loss surgery before starting this test as there is a risk of dumping syndrome and/or reactive hypoglycaemia. You should also check with your referring doctor before starting the test.

SA Pathology provides GTTs at most collection centres across South Australia. For more information, or to book an appointment, please call us on 8222 3000. For regional areas, please contact your local collection centre.