This website is intended for an Australian and New Zealand audience who are interested in acromegaly
This website is intended for an Australian and New Zealand audience who are interested in acromegaly

Oral glucose tolerance test

The oral glucose tolerance test, or OGTT, is generally done in the morning and will require you to fast for 8 to 10 hours before the test.   This includes having no food or fluids such as tea, coffee or fruit juice.  You may however have sips of water if you are thirsty.

When you go in for the test, a blood sample will be taken and you will be given a glucose (‘sugary’) liquid that you will need to drink within 5 minutes.

A blood sample will be collected 1 hour and 2 hours after you finished drinking the glucose liquid.

In people without acromegaly, the glucose in the drink will normally cause growth hormone levels to fall.  If your body is making too much of the hormone, these levels will not go down enough, which helps confirm the diagnosis of acromegaly.

The three main elements of the oral glucose tolerance test

IGF-1 measurement

A reliable way to track growth hormone in the body is by measuring the level of IGF-1 (insulin growth factor) in the blood.

IGF-1 measurement is the most accurate screening blood test.  In most cases, a high IGF-1 level suggests that you have acromegaly.

IGF-1 measurement is often done at the same time as an oral glucose tolerance test.


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Please always consult a healthcare professional if you require healthcare advice or if you have any specific concerns regarding your acromegaly, its treatment or side effects. The information provided here is not intended to replace professional advice. This website has been developed by Ipsen in collaboration with those living with acromegaly and the healthcare professionals who care for them. Ipsen would like to thank everyone for their valuable insights and stories. All names used on this website are not necessarily real names. Visit our website for more information about us, or to contact us directly. Website supported by Thrivase Pty Ltd.

SOM-AU-000711. Last reviewed: November 2023

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