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

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

This test measures your blood sugar levels before and after drinking a sugary liquid to check how your body processes glucose over time.

Quick summary

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

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

Key facts at a glance

LOINC
83587-6
Short code
OBGYN Nurse Note
Synonyms
OBGYN Nurse Note
Category
chemistry
Sample
serum
Container
Red-top tube (SST)
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
Method
obstetrics-and-gynecology-nurse
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 an OGTT if you have symptoms of high or low blood sugar, a family history of diabetes, unexplained weight changes, or if you’re pregnant. It’s also used to diagnose conditions like diabetes or prediabetes.

What to Expect Before the Test

You’ll fast for 8–12 hours before the test. Bring comfortable clothing and wear shoes you can easily walk in. You’ll drink a sugary liquid, and your blood will be drawn at two time points: before drinking and 2 hours later.

During the Test

A healthcare provider will take blood samples from a vein in your arm. You may feel a slight pinch, but it’s quick and shouldn’t cause discomfort. The test itself takes about 2 hours.

What the Results Mean

Results help determine if your body handles glucose normally. Abnormal results may indicate diabetes, insulin resistance, or other metabolic conditions that need further evaluation.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

◆Associated findings1

Short name

OGTT (2-hour plasma glucose)

Frequently asked questions

What does a high or low 2-hour glucose level indicate?
A high 2-hour glucose level after drinking the sugary liquid may suggest diabetes or prediabetes. A low level could indicate an error in the test or rare conditions like reactive hypoglycemia.
How long does it take to get my results?
Results are typically available within 1–3 business days, depending on your lab. Your doctor will discuss them with you during a follow-up visit.
Can I eat or drink anything before the test?
No, you must fast (only water is allowed) for 8–12 hours before the test. Avoid caffeine, alcohol, or sugary foods/drinks to ensure accurate results.
  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