✍️ Edited by Farhan Ahmed, Editor, MedTestBD · Last updated: August 2026
What is the OGTT?
The Oral Glucose Tolerance Test (OGTT) evaluates how your body processes sugar over a set time period. After fasting overnight, you drink a standardised glucose solution (usually 75g of glucose in water), and blood sugar levels are measured before and at set intervals — typically at 1 hour and 2 hours — after the drink. It is more comprehensive than a fasting blood sugar test and is the gold standard for diagnosing gestational diabetes during pregnancy.
Why is the OGTT Done?
- To diagnose gestational diabetes — routinely performed at 24–28 weeks of pregnancy
- To diagnose type 2 diabetes when fasting blood sugar results are borderline
- To diagnose prediabetes (impaired glucose tolerance) — a warning state before diabetes develops
- To investigate reactive hypoglycaemia — abnormally low blood sugar after eating
- To evaluate women with polycystic ovary syndrome (PCOS), who have a higher risk of insulin resistance
Normal OGTT Results
| Time Point | Normal | Prediabetes | Diabetes |
|---|---|---|---|
| Fasting (0 min) | Below 5.6 mmol/L (100 mg/dL) | 5.6–6.9 mmol/L | 7.0+ mmol/L |
| 2-hour post-glucose | Below 7.8 mmol/L (140 mg/dL) | 7.8–11.0 mmol/L | 11.1+ mmol/L |
For gestational diabetes, different thresholds apply depending on whether a 75g or 100g glucose load is used and which guideline the doctor follows (WHO or IADPSG). Your obstetrician will interpret results using pregnancy-specific criteria.
How to Prepare for the OGTT
- Fast for 8–12 hours before the test — only water is allowed during this period
- Eat your normal diet (including carbohydrates) for at least 3 days before the test — a low-carb diet in the days before can falsely impair glucose tolerance
- Avoid heavy exercise, smoking, and caffeine on the day of the test
- Inform your doctor about any diabetes medications or steroids you take
- Remain seated and resting throughout the test — physical activity between blood draws affects glucose levels
- The test takes 2–3 hours in total — bring something to read and stay at the diagnostic center between blood draws
OGTT Price in Bangladesh
OGTT prices vary between diagnostic centers across Bangladesh. Compare OGTT test prices on MedTestBD →
Normal ranges cited on this page are based on MedlinePlus and WHO guidance. Prices are collected from public sources and may change — confirm with the facility before visiting. This information is for general reference only and is not medical advice. Always consult a qualified physician.
