GLUCOSE TOLERANCE TEST 75G GTT Test

The Glucose Tolerance Test (GTT) – 75 g is an oral glucose tolerance test used to assess how effectively the body processes glucose. It is commonly used to evaluate diabetes, impaired glucose tolerance, and gestational diabetes mellitus (GDM).

For the standard 75 g OGTT during pregnancy, a fasting blood sample is collected first. The individual then drinks a solution containing 75 grams of glucose, followed by blood samples at 1 hour and 2 hours. This three-point assessment provides a detailed picture of how blood glucose changes after the glucose load.

For the one-step approach to diagnosing gestational diabetes, commonly used thresholds are 92 mg/dL fasting, 180 mg/dL at 1 hour, and 153 mg/dL at 2 hours. Meeting or exceeding any one of these values may meet the diagnostic criteria for GDM under this approach.

In India, some protocols use a 75 g glucose load with a 2-hour blood glucose measurement regardless of fasting status, particularly the DIPSI approach. Therefore, the exact procedure and interpretation should follow the protocol specified by the healthcare provider or laboratory.

GLUCOSE TOLERANCE TEST 75G GTT Test is Recommended for Individuals:

• Pregnant women undergoing gestational diabetes screening
• Women generally being evaluated around 24–28 weeks of pregnancy
• Pregnant individuals with risk factors for gestational diabetes
• Women with a previous history of gestational diabetes
• Individuals with a family history of diabetes
• People with borderline or abnormal blood glucose results
• Individuals being evaluated for prediabetes or diabetes
• Patients with symptoms suggestive of abnormal glucose metabolism
• Individuals whose healthcare provider recommends a 75 g oral glucose tolerance test

FAQs

1. How is the 75 g GTT performed?
Depending on the protocol, you may first provide a fasting blood sample, drink a solution containing 75 g of glucose, and then provide blood samples at specified intervals, commonly at 1 and 2 hours.

2. Do I need to fast before a 75 g GTT?
For the standard one-step 75 g OGTT, an overnight fast of at least 8 hours is generally required. However, some Indian protocols, such as the DIPSI approach, use a 75 g glucose load without requiring fasting. Follow the specific instructions provided by your healthcare provider or laboratory.

3. What can an abnormal 75 g GTT result indicate?
Abnormal results may indicate impaired glucose tolerance, diabetes, or gestational diabetes, depending on the patient’s clinical situation and the protocol used. The results should be interpreted using the appropriate laboratory and clinical reference criteria.