Fitness Testing
Fitness Testing > Tests > Health > Glucose Tolerance Test (GTT)
Oral Glucose Tolerance Test (GTT)
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aim: A glucose tolerance test determines how quickly glucose is cleared from the blood. The test is usually used to test for diabetes and insulin resistance. -
equipment required: blood glucose analyzer, blood collection apparatus, glucose, scales.
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description / procedure: The test is performed immediately following a fast of between 8-16 hours. A fasting blood glucose measurement is performed immediately prior to the test. If this level is greater than 7.0 mmol/L, the test is usually not performed as this level signifies diabetes mellitus. The patient is then given a glucose solution to drink. Adults are given 75 grams of glucose, children are given an amount dependent on their weight: 1.75 g/kg body weight (up to 75 grams maximum). The patient is instructed to rest, then another blood glucose measurement is taken after 2 hours.
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results:
Rating |
Fasting |
2 Hour |
Normal |
< 5.5 mmol/L |
< 7.8 mmol/L |
Impaired glucose tolerance |
< 5.5 mmol/L |
7.8 - 11.0 mmol/L |
Impaired fasting glycemia |
5.5 - 6.9 mmol/L |
< 7.8 mmol/L |
Diabetes mellitus: |
> 7.0 mmol/L |
> 11.1 mmol/L |
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contraindications: the GTT should not be done if the patient is ill, is known to have diabetes mellitus, or has symptoms suggestive of diabetes mellitus (e.g. fasting plasma glucose >7.0 mmol/L or random plasma glucose >11.1 mmol/L.
Related Pages
- blood testing
- other Health Related Tests
- article: Are you at Risk of Contracting Diabetes?
- article: How To Prevent Type 2 Diabetes
