Glucose Tolerance Test

The glucose tolerance test (GTT) is a medical test used to assess the body's ability to regulate blood sugar levels after consuming a sugary drink.

Purpose

The purpose of the GTT is to:

• Diagnose diabetes, prediabetes, and impaired glucose tolerance
• Monitor the effectiveness of treatment for diabetes
• Assess the risk of developing gestational diabetes in pregnant women

Procedure

The GTT typically involves the following steps:

1. Fasting: The patient is required to fast for at least 8 hours before the test.
2. Glucose drink: The patient is given a sweet drink containing a known amount of glucose (usually 75g or 100g).
3. Blood samples: Blood samples are taken at intervals (usually 1-2 hours) after consuming the glucose drink to measure blood sugar levels.
4. Results: The results are used to determine how well the body is able to regulate blood sugar levels.

Interpretation of Results

The results of the GTT are interpreted as follows:

• Normal: Blood sugar levels return to normal within 2 hours after consuming the glucose drink.
• Impaired glucose tolerance: Blood sugar levels are higher than normal but not high enough to be classified as diabetes.
• Diabetes: Blood sugar levels are significantly higher than normal, indicating that the body is not able to regulate blood sugar effectively.

Risks and Side Effects

The GTT is generally a safe test, but some patients may experience:

• Nausea or vomiting after consuming the glucose drink
• Dizziness or lightheadedness due to fasting or changes in blood sugar levels
• Discomfort or bruising at the needle site where blood samples are taken

Preparation

To prepare for the GTT, patients should:

• Fast for at least 8 hours before the test
• Avoid strenuous exercise and smoking on the day of the test
• Tell their doctor about any medications they are taking, as some may affect the results of the test

Special Considerations

The GTT may not be suitable for everyone, particularly:

• Pregnant women with a history of gestational diabetes or those at high risk of developing it
• Patients with a history of severe hypoglycemia (low blood sugar)
• Patients taking certain medications that may affect blood sugar levels, such as corticosteroids or beta-blockers