GLUCOSE TOLERANCE TEST 100G GTT Test

The Glucose Tolerance Test (GTT) – 100 g is an oral glucose tolerance test primarily used as a diagnostic test for gestational diabetes mellitus (GDM). It is commonly performed after an abnormal 50 g glucose screening test during pregnancy.

For the traditional 3-hour 100 g GTT, a fasting blood sample is collected first. The individual then drinks a solution containing 100 grams of glucose, followed by blood samples at 1, 2, and 3 hours. This provides four glucose measurements in total and shows how effectively the body handles a significant glucose load.

Under the commonly used Carpenter-Coustan criteria, gestational diabetes is diagnosed when at least two of the following values meet or exceed the specified thresholds: fasting 95 mg/dL, 1-hour 180 mg/dL, 2-hour 155 mg/dL, or 3-hour 140 mg/dL. Diagnostic criteria can vary according to the clinical protocol used.

GLUCOSE TOLERANCE TEST 100G GTT Test is Recommended for Individuals:

• Pregnant women who have an abnormal 50 g glucose screening test
• Women being evaluated for gestational diabetes
• Pregnant individuals with risk factors for GDM
• Women with a previous history of gestational diabetes
• Pregnant women with a strong family history of diabetes
• Individuals with previous abnormal glucose tolerance results
• Pregnant women whose healthcare provider recommends a 100 g OGTT
• Patients requiring confirmation after an elevated glucose screening result

FAQs

1. How is the 100 g GTT performed?
A fasting blood sample is collected first. You then drink a solution containing 100 g of glucose, followed by blood samples at approximately 1, 2, and 3 hours. The complete test generally takes around three hours.

2. Do I need to fast before a 100 g GTT?
Yes. The 100 g GTT is generally performed after an overnight fast of at least 8 hours. During the test, you should not eat, smoke, or undertake strenuous activity. Follow the specific preparation instructions provided by your healthcare provider or laboratory.

3. What happens if the 100 g GTT result is abnormal?
An abnormal result may indicate gestational diabetes. Using the Carpenter-Coustan criteria, at least two elevated values among the fasting, 1-hour, 2-hour, and 3-hour measurements are traditionally required for diagnosis. Your healthcare provider will interpret the results according to the testing protocol being used.