Gestational Diabetes
Gestational Diabetes Test: When and What Results Mean
Written by Dr. Ajay V. Kaduskar, Diabetologist, Nagpur
MD (Medicine), PGDHSc (Diabetology), FEACD (The Netherlands)
Published · 4 min read
Quick answer
Most women are tested for gestational diabetes between 24 and 28 weeks of pregnancy using an oral glucose tolerance test (OGTT). In India, women are often tested early in pregnancy and again at 24 to 28 weeks if the first test is normal. The test involves a glucose drink and blood samples. Abnormal results lead to diet changes, monitoring and sometimes treatment.
Gestational diabetes is high blood sugar that first appears during pregnancy. It often has no symptoms, so testing is the only way to find it. Early detection protects both mother and baby. Here is what to expect.
Who should be tested?
In India, many guidelines advise testing all pregnant women, because the risk of diabetes is high. Early testing in the first trimester is advised for women who:
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Are overweight or obese
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Have a family history of diabetes
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Had gestational diabetes in a previous pregnancy
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Have PCOS
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Have had a large baby before
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Have high blood pressure
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Are older than 30 to 35 years
When is the test done?
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First visit or early pregnancy: Often for high-risk women, to detect pre-existing diabetes.
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24 to 28 weeks: For all women with a normal early test.
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Later in pregnancy: If symptoms or concerns arise, such as a large baby on scan.
What are the test options?
One-step OGTT
You fast overnight for at least 8 hours. A fasting blood sample is taken. You drink a solution containing 75 g of glucose. Blood samples are taken at one and two hours. This approach is commonly used in India and recommended by several international groups.
Two-step test
First, a 50 g glucose challenge is done without fasting, with one blood test at one hour. If high, a 100 g OGTT is done with fasting. This approach is used in some countries.
Your doctor will advise which one is used for you.
What are the diagnostic values?
For the common 75 g OGTT (IADPSG/WHO criteria), gestational diabetes is diagnosed if any one value is:
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Fasting: 92 mg/dL or higher
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At 1 hour: 180 mg/dL or higher
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At 2 hours: 153 mg/dL or higher
Some Indian guidelines use a single 2-hour value of 140 mg/dL or higher after a 75 g glucose load. Your doctor will explain which criteria they follow.
How do you prepare?
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Eat normally for the three days before, including adequate carbohydrates.
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Fast for 8 to 14 hours as instructed, drinking water only.
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Do not smoke or exercise heavily on the morning.
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Tell the lab about any medicines or vomiting.
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Remain seated and rest during the test.
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Bring a snack for afterwards.
What if the drink makes you feel sick?
Some women feel nauseated after the sweet drink. Sip it slowly over five minutes. If you vomit, inform the staff. The test may need to be repeated.
What happens after an abnormal result?
You will be referred to a diabetologist and dietitian, and taught:
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Home blood sugar monitoring
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A healthy meal plan with measured carbohydrates
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Safe physical activity such as walking
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When medicines or insulin might be needed
Regular scans and checks track the baby's growth.
What if the result is normal?
You may still be at risk if you had symptoms or risk factors. Repeat testing at 24 to 28 weeks if the early test was normal, or if gestational diabetes is suspected later. Continue healthy habits.
When should you see a doctor?
Seek advice if you have excessive thirst, frequent urination, blurred vision, recurrent infections, a large baby on scan or excess amniotic fluid.
What to remember
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Testing is done in early pregnancy for high-risk women and at 24 to 28 weeks for all.
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The OGTT uses a glucose drink and blood samples.
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One abnormal value may be enough for diagnosis under common criteria.
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Prepare by fasting and eating normally in the days before.
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Early diagnosis protects mother and baby.
A positive test is not a failure. It is an opportunity to protect your pregnancy with simple steps. For guidance, consult Dr. Ajay V. Kaduskar, a diabetologist at Niramay Clinics in Nagpur.
Sources and further reading
Frequently asked questions
Usually between 24 and 28 weeks. In India, high-risk women may be tested in the first trimester too. Your doctor will advise the timing.
You fast, give a blood sample, drink a glucose solution, and have blood drawn again after one and two hours. The results show how your body handles sugar.
Fasting below 92, one hour below 180 and two hours below 153 mg/dL under IADPSG criteria. Your doctor may use slightly different criteria.
Not for the fasting OGTT. You need to fast 8 to 14 hours and drink only water. Eat normally during the days before the test.
Yes. The test is widely used and considered safe. The glucose load is similar to a sweet drink. Tell your doctor if you feel unwell.
Do not panic. See a diabetologist and dietitian, learn to monitor your sugars and follow a plan. Most women control gestational diabetes with diet and activity.
Related reading
- Full guide: gestational diabetes
- Gestational Diabetes Diet: Indian Foods and Meal Timing
- When Is Insulin Needed in Gestational Diabetes?
- Does Gestational Diabetes Go Away After Delivery?
- After Gestational Diabetes: When to Test for Type 2
If you would like advice suited to your own reports and medicines, you can book an appointment or visit Niramay Clinics in Dhantoli, Nagpur.
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