Oral Glucose Tolerance Test (OGTT) and GDM Screening in Pregnancy: A Complete Guide for Indian Moms (2026 Complete Guide)

TL;DR

The Oral Glucose Tolerance Test (OGTT) is a simple blood sugar test used to screen for Gestational Diabetes Mellitus (GDM), which is high blood sugar that first appears during pregnancy (WHO, ACOG). It is usually done between weeks 24 and 28, and earlier for high-risk women. In India, the government recommends a simple single-step 75g test (the DIPSI method), where a 2-hour blood sugar of 140 mg/dL or more confirms GDM (FOGSI, NHM). GDM often has no symptoms, which is why screening matters. With the right diet, activity, monitoring and (if needed) medication, most women with GDM have healthy pregnancies and babies.

Quick Answer

An OGTT is a blood test that checks how your body handles sugar, used to screen for gestational diabetes between weeks 24 and 28. You drink a glucose solution, then your blood sugar is measured. In India, a 2-hour value of 140 mg/dL or more (DIPSI method) means GDM. It is usually treatable.

Author: Mylo Editorial Team, Mylo Parenting Desk
Medically reviewed by: Mylo Editorial Board, aligned with WHO, ACOG, FOGSI and DIPSI guidance
Last updated: 22 June 2026

Medical Disclaimer: This article is for informational purposes only and is not a substitute for professional medical advice. Blood sugar cutoffs, methods and treatment vary by guideline and by individual. Always follow your own doctor's instructions for testing and managing gestational diabetes.

Key Takeaways

• The OGTT screens for gestational diabetes (GDM), high blood sugar that first appears in pregnancy (WHO)

• Screening is usually done between weeks 24 and 28, and at the first visit for high-risk women

• India mainly uses the single-step 75g DIPSI test; a 2-hour value of 140 mg/dL or more confirms GDM (FOGSI)

• GDM often has no symptoms, so testing is the only reliable way to detect it

• Indian women have a higher risk of GDM, so universal screening is recommended (ICMR)

• Untreated GDM can lead to a large baby, delivery complications and future diabetes risk

• Most cases are managed with diet, activity and monitoring; some need insulin

• The test is low cost and widely available, often free at government centres

What Is the Oral Glucose Tolerance Test (OGTT)?

The OGTT is a blood test that measures how well your body processes sugar (glucose). During pregnancy, hormones from the placenta can make your body more resistant to insulin, which can raise blood sugar. The OGTT checks whether your blood sugar stays in a healthy range after you drink a measured glucose solution (Mayo Clinic, NHS).

Featured answer: An OGTT measures your blood sugar before and after drinking a glucose solution to see how your body handles sugar during pregnancy. It is the standard test for gestational diabetes, usually performed between weeks 24 and 28. A raised result means your body is not managing blood sugar well and needs care.

What Is Gestational Diabetes (GDM)?

Gestational Diabetes Mellitus (GDM) is high blood sugar that is first recognised during pregnancy, usually in the second or third trimester (ACOG). It happens because pregnancy hormones reduce how well insulin works, and in some women the body cannot make enough extra insulin to keep up. GDM usually goes away after delivery, but it raises the future risk of type 2 diabetes for both mother and child.

When Is GDM Screening Done in Pregnancy?

The timing depends on your risk level. Standard screening happens in the second trimester, but high-risk women are tested earlier and may be retested.

In India, national guidelines recommend testing all pregnant women at the first visit and again at weeks 24 to 28, because of the high background risk (NHM, FOGSI).

How Is the OGTT Done? The Main Methods Explained

There is more than one accepted way to do the test. India most commonly uses the simple single-step DIPSI method because women do not need to come fasting, which improves real-world coverage. The table below compares the main approaches.

Sources: FOGSI, WHO, ACOG.

What Are the Normal OGTT Values and Cutoffs?

Blood sugar cutoffs differ slightly by method. The table below gives the widely used reference values. Your lab report will state which method was used.

Sources: WHO, FOGSI. Always interpret results with your doctor.

How Should You Prepare for the OGTT?

Preparation depends on the method your doctor uses. For the fasting (WHO/IADPSG) test you must not eat overnight, while the DIPSI test can be done without fasting. The simple checklist below covers both.

Who Is at Higher Risk of Gestational Diabetes?

Some women are more likely to develop GDM and may be screened earlier. You have a higher risk if you (ACOG, NHS):

• Are overweight or have a high BMI

• Have a family history of diabetes

• Had GDM in a previous pregnancy

• Previously had a large baby (about 3.5 kg or more)

• Have PCOS (polycystic ovary syndrome)

• Are of South Asian background, which carries a higher baseline risk

• Are older than about 30 years

What Are the Symptoms of Gestational Diabetes?

GDM usually causes no clear symptoms, which is exactly why screening is so important. When symptoms do appear, they can include (Mayo Clinic, NHS):

• Increased thirst

• Needing to urinate more often than usual

• Unusual tiredness

• A dry mouth

Because these overlap with normal pregnancy feelings, never rely on symptoms alone. The OGTT is the only reliable way to know.

Why Does GDM Matter? Risks If Left Untreated

Well-managed GDM usually leads to a healthy pregnancy. Untreated or poorly controlled GDM can raise the risk of complications for both mother and baby.

Sources: WHO, ACOG.

How Is Gestational Diabetes Managed?

Most women control GDM with lifestyle steps alone, and a smaller number need medication. Your doctor will set personalised blood sugar targets and a monitoring routine (ADA, ACOG).

What blood sugar targets are aimed for?

Targets are individual; follow the numbers your doctor gives you. Source: ADA.

What Does the OGTT Cost in India?

The test is low cost and widely available, and is offered free at many government facilities under national maternal health programmes.

Indian Context: What Indian Mothers Should Know

• Higher risk: Indian and South Asian women have a higher risk of GDM, so India recommends testing every pregnant woman, not just high-risk ones (ICMR, FOGSI)

• Simple test: The DIPSI single-step 75g non-fasting test was adopted nationally so that no woman is turned away just because she ate before coming

• Free care: Government schemes such as JSY and PMSMA support free antenatal testing and care

• Indian diet tips: Choose whole grains like ragi, jowar and bajra, add dal and sabzi, limit white rice, sugary chai and sweets; pair carbs with protein and fibre

• Festive caution: Be extra mindful around mithai during festivals; a small portion with a doctor's nod is better than skipping monitoring

• Vaccination and visits: Keep up your TT or Tdap and routine antenatal visits alongside GDM care

• Emergency number: Dial 108 for ambulance services across most states

Myths vs Facts About OGTT and GDM

FAQs: OGTT and GDM Screening

When is the OGTT done in pregnancy?
The OGTT is usually done between weeks 24 and 28, and earlier (often at the first visit) for women at higher risk (ACOG). Your doctor decides the exact timing based on your risk factors.

GDM ka test kab hota hai? (Hinglish)
Gestational diabetes ka OGTT test aksar 24 se 28 hafte ke beech hota hai. Agar aapko zyada risk hai (jaise family history, pichli pregnancy mein GDM, ya zyada weight), to yeh test pehli visit par bhi ho sakta hai. India mein 75g wala DIPSI test common hai, jisme 2 ghante baad sugar 140 mg/dL ya usse zyada ho to GDM mana jata hai.

Do I need to fast for the OGTT?
It depends on the method. The WHO and IADPSG fasting test needs an 8 to 12 hour overnight fast, while the DIPSI test used widely in India can be done without fasting (FOGSI). Ask your doctor or lab which method they use.

What is a normal OGTT result?
For the Indian DIPSI 75g test, a 2-hour value below 140 mg/dL is considered normal (FOGSI). For the WHO fasting test, fasting below 92, 1-hour below 180 and 2-hour below 153 mg/dL are normal. Your report will state the method used.

OGTT ke liye kya khana mana hai? (Hinglish)
Agar fasting wala test hai, to raat ko 8 se 12 ghante kuch nahi khana, sirf paani pi sakti hain. Non-fasting (DIPSI) test mein fasting ki zaroorat nahi. Test ke dauraan baithkar aaram karein, kuch khaayein ya smoke na karein. Test ke baad ke liye ek halka snack saath rakhein.

Is gestational diabetes dangerous for my baby?
Well-controlled GDM usually leads to a healthy baby. If left untreated, it can cause a larger baby, delivery difficulties and low blood sugar in the newborn (WHO). This is why early detection and management matter so much.

Can I prevent gestational diabetes?
You cannot always prevent it, since hormones play a big role, but a healthy weight before pregnancy, a balanced diet and regular activity can lower your risk (ADA). If you are high-risk, your doctor may guide you early.

Will GDM go away after delivery?
In most women, blood sugar returns to normal soon after birth (Mayo Clinic). However, you should have a follow-up test after delivery, as GDM raises your future risk of type 2 diabetes.

What foods should I eat if I have GDM?
Focus on whole grains like ragi and jowar, plenty of vegetables and dal, lean protein and fibre, while limiting white rice, sugary drinks and sweets (ICMR). Eating smaller, frequent meals helps keep blood sugar steady. Your doctor or dietitian will personalise this.

References

1. World Health Organization (WHO). "Diagnostic criteria and classification of hyperglycaemia first detected in pregnancy." https://www.who.int

2. American College of Obstetricians and Gynecologists (ACOG). "Gestational Diabetes." https://www.acog.org/womens-health/faqs/gestational-diabetes

3. FOGSI (Federation of Obstetric and Gynaecological Societies of India). "GDM and DIPSI guidance." https://www.fogsi.org/

4. Ministry of Health and Family Welfare / National Health Mission. "National Guidelines for Diagnosis and Management of Gestational Diabetes Mellitus." https://nhm.gov.in

5. American Diabetes Association (ADA). "Management of Diabetes in Pregnancy." https://diabetes.org

6. Mayo Clinic. "Gestational Diabetes." https://www.mayoclinic.org/diseases-conditions/gestational-diabetes

7. NHS UK. "Gestational Diabetes." https://www.nhs.uk/conditions/gestational-diabetes/

8. Indian Council of Medical Research (ICMR) / NIN. "Dietary Guidelines for Indians." https://www.icmr.gov.in