Glucose Tolerance Test (GTT)

Normal results:

• In non-pregnant individuals, typically, fasting blood sugar is below 6 mmol/L and the values 2 hours after drinking a sugary drink can go up to 7.8 mmol/L. These results mean that the body can absorb glucose normally, and the person does not have diabetes.
• In pregnant women, the typical value would be either equivalent to or below 7.8 mmol/L after 1 hour of drinking the sugar water.

Abnormal results:

Higher than normal results could indicate either an early sign of diabetes or presence of clinical diabetes.

In case of non-pregnant individuals, glucose levels between 7.8-11.1 mmol/L 2 hours after sugar intake are an indication of a pre-diabetic condition. This would mean that the individual is at risk for diabetes and should get themselves checked yearly.

A value higher than 11.1 mmol/L is an indication of diabetes and requires immediate attention of a medical practitioner.

In pregnant women, a value of more than 7.8 mmol/L could indicate gestational diabetes. The doctor may order a repeat test before beginning an appropriate treatment.

Disclaimer: All results must be clinically correlated with the patient’s complaints to make a complete and accurate diagnosis. This information is provided from a purely educational point of view and is in no way a substitute for medical advice by a qualified doctor.

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A healthcare provider will recommend a GTT under the following circumstances:

• In undetermined cases of diabetes
• During 26-28 weeks of pregnancy
• In women, 6-8 weeks after delivery
• Polycystic ovarian syndrome

If results from other diabetes tests are indeterminate, an individual may be asked for GTT as it is a gold standard for such cases. Doctors recommend a yearly check for diabetes in high-risk patients to eliminate any further risks.

During pregnancy, a woman’s body undergoes several metabolic adjustments for the growing foetus. Therefore, GTT is a standard test in the 3rd trimester of pregnancy. It is performed to eliminate the risk of gestational diabetes that might affect mother’s health.

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GTT protocols for pregnant women and non-pregnant individuals differ slightly.

Non-pregnant individuals:

• A blood sample is collected from the arm using a sterile needle after swabbing the concerned area with an appropriate antiseptic solution. Some people experience a little discomfort at needle insertion site, which disappears soon after the test.
• A sugary drink is given to the individual, which they should consume immediately.
• There is a waiting period of 2 hours after that, during which, eating, drinking any other juices or caffeinated beverages, and smoking is not permitted.
• Another blood sample is collected at the end of 2 hours.

Pregnant women:

• The pregnant woman is given a glass of sugary drink, which she should consume immediately.
• After a waiting period of 1 hour, a blood sample is collected from her arm using a sterile needle. Eating or drinking any juices or fluids is not permitted during the waiting period.
• In case of any blood sugar abnormalities in test results, the doctor may require another test where they would follow the same procedure as that for non-pregnant individuals.

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Maintaining regular food intake for 3 days preceding the test is necessary for GTT. The doctor should be informed about any existing medical conditions or intake of any medications or herbal supplements. Do not change the course of any medication without consulting your doctor. Pregnant women should consult the doctor to get further instructions for this test.

Non-pregnant individuals:

Individuals should fast for about 8-10 hours before the test. During this time, he/she can drink water, but food, juices and caffeine should not be taken before the test. Smoking should also be avoided during fasting hours. Generally, GTT is performed in the morning.

Pregnant women:

GTT can be performed at any time during the day for pregnant women. In exceptional conditions, the doctor may ask to follow the standard preparation instructions that are recommended for non-pregnant individuals.

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