Oral Glucose Tolerance Test

Why am I having this test?

This test is carried out to diagnose various conditions including:

• Acromegaly – excessive growth hormone levels
• Reactive Hypoglycaemia – low blood sugar levels after meals

Who carries out this test?

A nurse who specialises in endocrinology is responsible for carrying out this test.

Where is the test carried out?

You will be sent a letter with details of the test and which department you will need to attend. If you wish, you may bring a companion with you and they may stay with you during the test.

How long will the test take?

The test usually takes approximately 3 hours to complete.

What do I need to do before the test?

• It is important that you have nothing to eat from 10.00pm the evening before the test. You may drink plain water freely.
• Please inform the endocrine specialist nurse as soon as you receive your appointment letter if you take any form of medicines for diabetes such as tablets or insulin.
• If you are a diabetic on medication, you may not need to take your medicines on the morning of the test, but bring it with you. The endocrine specialist nurse will inform you about any changes that may need to be made to your medication doses.
• You may take all your other medicines as usual.

What happens during the test?

• You will meet the endocrine specialist nurse who is responsible for the test on your arrival in the department. The nurse will explain about the test and you will be given the opportunity to ask questions.
• A cannula, a fine plastic tube, is inserted into a vein in your arm and this is used to take blood samples. There may be some discomfort for a few seconds.
• You will be given a sweet sugary drink.
• A blood sample will be taken from the cannula, at intervals of 30 minutes for a total of two hours.
• Throughout the test you can only drink plain water. Flavoured water is not allowed.
• At the end of the test the cannula will be removed and a small dressing applied. This can be removed when you get home.

Are there any side effects?

The test is usually well tolerated. Rarely, some patients may feel slightly nauseous.

What happens after the test?

• On completion of the test you will be safe to return home or to work alone.
• The results will be discussed at your next clinic visit or a letter will be sent to you and your GP.
• The nurse looking after you will arrange a further appointment as required.

If you require more details please contact the Specialist Nurses in Endocrinology:
Tel: 01274 382019 Monday – Friday between 8.00am and 4.00pm except Bank Holidays