Skip to content

Oral Glucose Tolerance Test (OGTT) with 2-Hour Plasma Glucose Measurement

Published: August 9, 2026Updated: August 16, 2026

This test measures your blood sugar level 2 hours after drinking a sugary liquid to check how your body processes glucose.

Quick summary

["Assesses how well your body manages blood sugar after eating."]

Medically reviewed by WellAlly Editorial TeamLast reviewed August 16, 2026Editorial policy

Key facts at a glance

LOINC
77455-4
Short code
Deprecated Hind+Mid ft XR tomo
Synonyms
Deprecated Hind+Mid ft XR tomo
Category
chemistry
Sample
serum
Container
Red-top tube (SST)
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
Method
xr-tomography
Specimen volume
5 mL
Stability
Room temperature: 4h, Refrigerated: 24h, Frozen: 7d
Hemolysis max
500
Lipemia max
1000
Icterus max
500
TAT
4–24 hours
Order
routine

What This Test Measures

The test involves drinking a standardized glucose solution and having blood drawn at specific intervals, including 2 hours post-drink. The 2-hour plasma glucose level is recorded to evaluate glucose tolerance.

Why It’s Done

Doctors may order this test to diagnose conditions like diabetes, prediabetes, or gestational diabetes, or to monitor existing diabetes management.

Preparation

You may need to fast for 8–12 hours before the test, but hydration is encouraged. Avoid caffeine or sugary foods/drinks on the day of testing.

Procedure

You’ll drink a sweet liquid, then blood samples are taken at baseline and at 30-minute intervals up to 2 hours. The 2-hour sample is specifically analyzed for glucose levels.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

Abnormally high 2-hour glucose levels (above normal thresholds) suggest impaired glucose tolerance, which can indicate prediabetes or diabetes. This test helps guide treatment plans and long-term health strategies.

Frequently asked questions

What does a high 2-hour glucose level mean?
A high result may indicate poor glucose control, which could require lifestyle changes, medication adjustments, or further evaluation for diabetes.
How soon will I get results?
Results are typically available within 1–3 business days, depending on lab processing times. Your doctor will discuss them with you.
Can I eat or drink anything before the test?
No, fasting is required for most of the test. However, you can drink water without sugar unless instructed otherwise by your provider.
  1. 1
    MedlinePlus — Laboratory TestsSource
  2. 2
    Lab Tests OnlineSource
  3. 3
    Mayo Clinic — Tests & ProceduresSource

Click any link to access the full source. PubMed Central (PMC) links provide free full-text access.

This information is for educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment.

Medical Disclaimer

This content is for general informational and educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment. Always seek the guidance of a qualified healthcare provider with any questions you have about a medical condition, and never disregard professional medical advice or delay seeking it because of something you read here.

If you think you may have a medical emergency, call your local emergency number or go to the nearest emergency department immediately.

Medically reviewed by WellAlly Editorial Team Last reviewed August 16, 2026. · Read our editorial policy