Description
Why It’s Done
The GTT (OGTT – 75 grams, 4 samples) is typically ordered for:
• Diagnosing Diabetes: It is used to confirm type 2 diabetes or gestational diabetes (in pregnant women).
• Screening for Prediabetes: If blood glucose levels are higher than normal but not yet in the diabetic range, it can identify impaired glucose tolerance (IGT).
• Gestational Diabetes Monitoring: The test is commonly performed during pregnancy (usually between 24–28 weeks) to screen for gestational diabetes mellitus (GDM).
• Monitoring Insulin Resistance: It may also be used in assessing insulin sensitivity or resistance.
• Diagnosing Metabolic Disorders: This test can help detect issues related to glucose metabolism and the ability of the body to regulate blood sugar after eating.
Preparation
To ensure the test is accurate:
• Fasting is required: You need to fast for 8–12 hours before the test (you may drink water).
• Avoid caffeine and alcohol: These can affect the test results, so refrain from consuming them the day before or the day of the test.
• Dietary restrictions: Stick to your normal diet before the test; do not eat or drink anything except water on the morning of the test.
• Medications: Inform your doctor of any medications you are taking. Some medications, like steroids, may affect glucose metabolism.
• Duration: The test will take about 3–4 hours in total. You will be asked to drink a glucose solution, and blood samples will be taken at 0 hours, 1 hour, 2 hours, and 3 hours after ingestion.
