Oral Glucose Tolerance Test (OGTT)
Also known as: GTT, Glucose Challenge
The OGTT checks how your body handles a measured glucose drink, and is used to diagnose diabetes in pregnancy.
Why it's done
- Diagnose gestational diabetes
- Diagnose diabetes when other tests are unclear
What it measures
Blood sugar before and after a 75 g glucose drink.
Preparation
Overnight fast; stay seated at the lab for 2 hours.
Normal range
2-hour value below 140 mg/dL is normal (pregnancy cut-offs differ)
Understanding results
Higher values indicate impaired glucose tolerance or diabetes.
Related conditions
Frequently asked questions
Why is the Oral Glucose Tolerance Test (OGTT) test done?
Diagnose gestational diabetes, Diagnose diabetes when other tests are unclear
How do I prepare for Oral Glucose Tolerance Test (OGTT)?
Overnight fast; stay seated at the lab for 2 hours.
What is the normal range for Oral Glucose Tolerance Test (OGTT)?
2-hour value below 140 mg/dL is normal (pregnancy cut-offs differ)
Medically reviewed by
Medical review pending
Last updated
9 October 2026
Sources
- ICMR standard treatment workflows
- Reference ranges vary by laboratory - always read your report with your doctor
This information is for general awareness and does not replace advice from a qualified doctor. Do not start, stop or change any medicine without medical advice.