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This website is intended for an international audience, excluding the United States, Canada and France

Oral glucose tolerance test

The oral glucose tolerance test, or OGTT, usually involves fasting from about 10 pm the evening before an early morning appointment at the hospital.

Blood samples are then taken every half an hour from a catheter (thin plastic tube) that is placed in a vein in your arm.

After the first blood sample you will be given a glucose (‘sugary’) drink.

Further blood samples will be taken every 30 minutes over a period of about 2–3 hours. After this, you will be able to have some breakfast and go home.

If you have acromegaly, your growth hormone levels will remain high throughout the test. This will happen even after a glucose drink, which would normally result in the growth hormone levels decreasing to very low levels.

The three main elements of the oral glucose tolerance test

IGF-1 measurement

Some of the blood you provide for the growth hormone test will be sent to a laboratory to measure your levels of IGF-1.

IGF-1 is a naturally occurring hormone produced by the liver that mediates nearly all of the actions of growth hormone on the tissues of the body.

Growth hormone profile throughout the day

Looking at how levels of your growth hormone change throughout the day is a test that some hospitals may use to monitor the effectiveness of treatment for acromegaly.

This test also involves fasting from about 10 pm the evening before an early morning appointment at the hospital.

To perform this test, a needle is placed in your arm and blood will be taken at intervals over several hours.

After the first sample is taken, you can have breakfast and you will be able to move about freely.

When will I get the results of the tests?

The results of the tests will usually be available in about 1 week, but this may vary from one hospital to another and may take up to 2–3 weeks.

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Ipsen
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 design and development by Kanga Health Ltd. Website reference SOM-ALL-000556