What is a normal glucose tolerance test range?

A typical adult range is around Fasting <100 mg/dL; 2-hour value <140 mg/dL (normal); 2-hour 140–199 mg/dL (impaired glucose tolerance); 2-hour ≥200 mg/dL (consistent with diabetes, ADA 75g OGTT). No India-specific national reference interval is published for this parameter; your lab's printed range is the most reliable comparison. Ranges vary by lab, method and equipment — the range printed on your own report is the one that applies to your result.

OGTT — What It Means in Your Blood Test

Q: What is OGTT?

You swallow a measured glucose (sugar) drink, then blood is drawn before and about two hours after. Comparing the two readings shows how fast your body pulls that sugar load out of the bloodstream. This test shows how well your body processes sugar, and is a standard check in pregnancy.

Q: What does a high OGTT result mean?

A higher two-hour value can mean your body is slower than usual at bringing sugar back down. It is worth discussing with your doctor. They can read it with your other results.

Q: What does a low OGTT result mean?

A lower two-hour value can mean your body brought the sugar down quickly. Your doctor can explain what it means for you.

Q: What can affect your OGTT result?

Several everyday factors can influence it, including recent activity, any illness or infection, some medicines, how long you fasted, your recent diet.

New to reading lab reports? Start with our guide to reading a blood test report

This checks how your body handles a sweet drink by measuring your blood sugar before and after.

The OGTT watches your body wrestle with a measured sugar drink over a short spell. Blood taken before and later shows how briskly you clear that load.

Also known as: Oral Glucose Tolerance Test, glucose tolerance test, 2-hour OGTT, GTT, 75g OGTT

Kept in balance

This isn't a case where higher or lower is better. Your body keeps it in a narrow band, and both directions can matter.

Last reviewed: 2026-08-16

What is OGTT?

You swallow a measured glucose (sugar) drink, then blood is drawn before and about two hours after. Comparing the two readings shows how fast your body pulls that sugar load out of the bloodstream.

Why is OGTT tested?

This test shows how well your body processes sugar, and is a standard check in pregnancy.

What is a normal OGTT range?

India: No India-specific national reference interval is published for this parameter; your lab's printed range is the most reliable comparison.
Global: Fasting <100 mg/dL; 2-hour value <140 mg/dL (normal); 2-hour 140–199 mg/dL (impaired glucose tolerance); 2-hour ≥200 mg/dL (consistent with diabetes, ADA 75g OGTT)

Ranges vary by lab, method and equipment — the range printed on your own report is the one that applies to your result.

Source: [ADA, 2024]

What does your OGTT value mean?

There is no widely-accepted set of value bands for this parameter. Compare your result with the reference range printed on your own report, and discuss it with your doctor.

What does a high OGTT result mean?

A higher two-hour value can mean your body is slower than usual at bringing sugar back down. It is worth discussing with your doctor. They can read it with your other results.

What does a low OGTT result mean?

A lower two-hour value can mean your body brought the sugar down quickly. Your doctor can explain what it means for you.

What can affect your OGTT result?

recent activity
any illness or infection
some medicines
how long you fasted
your recent diet

In the Indian context

In India, the DIPSI approach supports a single non-fasting 75g glucose test in pregnancy, because fasting before the test is often hard to arrange [DIPSI].

Questions to ask your doctor

About this result

What do my before-and-after glucose readings say about how my body handles sugar?
If I am pregnant, what does my OGTT result mean for me and my baby?

What to do next

Based on my OGTT, would changes to food and activity help, or do we need to do more?
Should my OGTT be read alongside my HbA1c or fasting sugar before we decide anything?

About retesting

If this OGTT is borderline, when should it be repeated to confirm the result?
In pregnancy, how often should glucose testing be repeated after this OGTT?

Frequently asked questions

What is OGTT?: You swallow a measured glucose (sugar) drink, then blood is drawn before and about two hours after. Comparing the two readings shows how fast your body pulls that sugar load out of the bloodstream. This test shows how well your body processes sugar, and is a standard check in pregnancy.
What is a normal glucose tolerance test range?: A typical adult range is around Fasting <100 mg/dL; 2-hour value <140 mg/dL (normal); 2-hour 140–199 mg/dL (impaired glucose tolerance); 2-hour ≥200 mg/dL (consistent with diabetes, ADA 75g OGTT). No India-specific national reference interval is published for this parameter; your lab's printed range is the most reliable comparison. Ranges vary by lab, method and equipment — the range printed on your own report is the one that applies to your result.
What does a high OGTT result mean?: A higher two-hour value can mean your body is slower than usual at bringing sugar back down. It is worth discussing with your doctor. They can read it with your other results.
What does a low OGTT result mean?: A lower two-hour value can mean your body brought the sugar down quickly. Your doctor can explain what it means for you.
What can affect your OGTT result?: Several everyday factors can influence it, including recent activity, any illness or infection, some medicines, how long you fasted, your recent diet.

Sources

ADA (2024) — Standards of Medical Care in Diabetes — Classification and Diagnosis of Diabetes
WHO (2006) — WHO diagnostic criteria for diabetes mellitus and intermediate hyperglycaemia
DIPSI (2014) — Diabetes in Pregnancy Study Group India — single-step testing guidance

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