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Oral Glucose Tolerance Test (OGTT) – 2-Hour Plasma Glucose

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

This test measures your blood sugar level 2 hours after drinking a sugary liquid. It helps check how your body processes glucose, especially useful for diagnosing or monitoring diabetes or other glucose-related conditions.

Quick summary

["Assesses how your body handles sugar over time, aiding diabetes diagnosis or management."]

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

Key facts at a glance

LOINC
35995-0
Short code
XR tomo Foot-L
Synonyms
XR tomo Foot-L
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

Why This Test Is Done

Your doctor may recommend this test if you have symptoms of high blood sugar (like frequent urination, excessive thirst, or unexplained weight loss), a family history of diabetes, or if you’re pregnant (gestational diabetes). It’s also used to monitor existing diabetes or prediabetes.

What to Expect Before the Test

You’ll fast for 8–12 hours before the test. Bring your medications with you—ask your doctor if you should skip any. You’ll drink a sugary liquid, and your blood will be drawn at the 2-hour mark.

What Happens During the Test

A healthcare provider will take a small blood sample from your arm. The test is quick but may cause a slight pinch. No special preparation is needed after the sample is taken.

What the Results Mean

Results are compared to standard ranges to determine if your blood sugar is normal, prediabetic, or diabetic. Your doctor will discuss these results with you in detail.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

Clinical Significance: This test is critical for diagnosing diabetes, gestational diabetes, and identifying prediabetes. It helps doctors track how well your body manages glucose over time, especially important for long-term health and preventing complications like nerve damage or heart disease.

Short name

OGTT (2-hour plasma glucose)

Frequently asked questions

What does a high or low result mean?
A high result (above normal ranges) suggests diabetes or impaired glucose tolerance. A low result is less common but may indicate other metabolic issues—your doctor will explain further based on your overall health.
Can I eat or drink anything before the test?
No, you must fast (no food or liquids except water) for 8–12 hours before the test. Avoid caffeine or sugary drinks during this time.
How long will I need to wait for my results?
Results are typically available within a few days to a week, depending on your lab. Your doctor will contact you with the final interpretation.
  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