General Information
A glucose tolerance test (GTT) is primarily used to diagnose diabetes mellitus and gestational diabetes (during pregnancy) by determining how well your body processes glucose (sugar). Testing involves measuring blood glucose levels after having consumed a known amount of glucose, usually given as a sweet drink, over multiple hours. The time of testing can vary depending on what your provider has ordered.
Reasons for Rescheduling
In instances where patients may feel unwell or experience vomiting during the test, it becomes necessary to repeat the testing process. Tests may also be rescheduled if fasting guidelines have not been met.
Preparing for your Test
For accurate test results it is important to maintain your normal level of exercise and usual diet three days prior to testing and follow the fasting guidelines for at least 8 hours before the test.
Fasting Guidelines
- Food: Fasting means not eating or chewing on any food, including chewing gum.
- Beverages: Only drink plain water. The day of your test be sure to hydrate by drinking two glasses of water.
- Medications: You should not stop your normal medications unless told to do so by your healthcare provider.
- No Smoking
Failing to adhere to the fasting guidelines may lead to cancellation of your glucose tolerance test.
What to Expect
- Upon arrival for your test, your fasting status will be confirmed and blood will be drawn for a fasting
glucose test. - Next, you will be given a sugary drink. Expect to have your blood drawn multiple times over the
course of the test. - You will need to stay near the lab throughout the test for safety purposes.
- If you have questions about the test procedure, please contact your provider or test location
Additional Information
National Institute of Diabetes and Digestive and Kidney Diseases
