Hi there! Thank you for your question. The test you are describing is called an Oral Glucose Tolerance Test (OGTT). As the name suggest, this test is designed to test your body’s tolerance to sugar more specifically glucose. Allow me to explain further.

Oral Glucose Tolerance Test used to be "gold standard" for diagnosing diabetes last time, but it is not done as often because is cumbersome to perform and a lot of preparation is needed. It is still commonly used during pregnancy for diagnosing gestational diabetes. The test should be performed as described by W.H.O. using a glucose/sugar load containing the equivalent of 75g glucose dissolved in water.

The test should be done in the morning after an overnight fast of between 8 and 14 hours and after at least 3 days of unrestricted diet (> 150g carbohydrate per day) and unlimited physical activity. The person should remain seated & should not smoke or consumed caffeine throughout the test. Blood should be drawn and the sugar levels are measured at 0 hours (pre- 75 g glucose load) and 2 hours after glucose load.

The results can be interpreted as such; in a person without diabetes, the glucose levels rise and then fall quickly, in someone with diabetes, glucose levels rise higher than normal and fail to come back down as fast. People with glucose levels between normal and diabetic levels have so-called impaired glucose tolerance (IGT).

People with impaired glucose tolerance do not have diabetes. A doctor will be able to make a diagnosis based of the glucose/sugar levels taken based on the guidelines provided. This is will make easier to targeted treatments such as lifestyle modification, anti-diabetic drugs and insulin therapy suitable for the diagnosis.

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