Oral Glucose Tolerance Test (OGTT)
A test where you drink a sugar solution and have blood sugar checked over two hours, used for diabetes and gestational diabetes.
Quick Summary
To diagnose diabetes, prediabetes and gestational diabetes.
Blood sugar before and after a glucose drink.
Fast overnight; rest during the test and don't eat, smoke or exercise.
Overview
In India, pregnant women are often tested with a 75 g glucose drink and a 2-hour reading, sometimes without fasting.
The OGTT is more sensitive than fasting sugar alone.
What It Measures
Fasting glucose
Before the drink.
2-hour glucose
After the drink.
How It's Performed
- 01
Preparation
Usually no special preparation. Tell the staff about medicines you take.
- 02
Blood sample
A small amount of blood is taken from a vein in your arm with a thin needle.
- 03
Afterwards
Press on the spot for a minute. A small bruise is common; you can go back to normal activities.
Reference Ranges
Note: Normal ranges vary by laboratory. Consult your report for the specific reference used.
| Parameter | Typical Range (Adult) | Units |
|---|---|---|
| 2-hour glucose (normal) | Below 140 | mg/dL |
| Gestational diabetes (single-step test in India) | 140 or above at 2 hours | mg/dL |
Interpreting Results & Next Steps
Discuss with Doctor
Some people feel sick after the drink; tell staff if you vomit. Normal ranges differ between laboratories, ages and sexes; always use the range printed on your report and ask your doctor what your results mean.
If values are High:
High results suggest diabetes or gestational diabetes.
Sources and further reading
Last updated 21 October 2026. For more detail, see these trusted health organisations.
- Diabetes Tests(opens in a new tab) · MedlinePlus, US National Library of Medicine