Indication
The diagnosis of diabetes mellitus.
Contraindications
Do not carry this out on patients who have diabetes mellitus, during acute illness, shortly after major surgery or if there is short term treatment with drugs known to impair glucose tolerance.
Patient preparation
The patient should have been on a normal diet (150g carbohydrate/day) and take part in usual physical activity for at least three days before the test.
Fast overnight (from midnight), only water is allowed.
The patient should not eat or smoke during the test.
Procedure
- A fasting sample of blood is taken for glucose estimation (grey vial)
- Give the patient 75g anhydrous glucose in water (Polycal 113ml in water, total volume 250 - 300ml).
This should be drunk within five minutes.
- Time 0 is when this has been finished.
- Blood samples for glucose (grey top vial) are taken
at 30, 60, 90 and 120 minutes after time 0.
Send all blood samples to the laboratory with one request form asking for a Full Glucose Tolerance Test
