THE METHOD OF PERFORMING A GLUCOSE TOLERANCE TEST

• Prepare a GTT chart for the patient on which to record collection times and test results.

• Collect a fasting venous blood sample into a bottle or tube containing fluoride-oxalate. Label the container ‘fasting blood’.

• Give the patient 75 g of glucose (D-glucose monohydrate) in 250–300 ml water, to be drunk in 5 to 15 minutes. To reduce nausea a few drops of lemon juice may be added to the water.

• Make a note of the time and enter on the GTT chart the time at which the next blood sample is to be collected, i.e. 2 hours after the glucose water has been drunk.

• Instruct the patient to rest quietly and not to eat, drink, exercise, smoke, or leave the hospital during the test.

• Inform the patient when the test will be completed.

• Important: If the patient should feel faint, very nauseated or begin to perspire excessively, call a medical officer.

• Collect the second blood sample at the correct time, labelling the container with the collection time.

• Measure the glucose concentration in each of the blood specimens.

• Enter the patient’s results on the GTT chart if the value of the control serum is acceptable.

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See also:

1. Blood glucose test
2. Glucose colorimetry method

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