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Glucose in Plasma (2-Hour Postprandial)

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

This test measures your blood sugar level two hours after eating to check how your body processes glucose. It helps diagnose conditions like diabetes or evaluate how well medications are working.

Quick summary

["Assesses blood sugar control after eating for diabetes management or prediabetes screening."]

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

Key facts at a glance

LOINC
72171-2
Short code
GTT 2h Pnl SerPl
Synonyms
GTT 2h Pnl SerPl
Category
glucose
Sample
serum
Container
Red-top tube (SST)
Units
N/A
Fasting
true
Population
adult
Sex
all
Age range
18–65 years
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 Matters

Your doctor may order this test if you have symptoms of high blood sugar (like frequent urination, excessive thirst, or fatigue) or if you’re at risk for diabetes. It’s also used to monitor treatment progress for people already diagnosed with diabetes.

What to Expect Before the Test

You’ll fast overnight (usually 8–12 hours) before the test, then eat a standard meal. Two hours later, a blood sample is drawn from your arm. No special preparation is needed beyond fasting.

How the Test Works

A small needle is used to collect blood from your arm. The sample is sent to a lab where glucose levels are measured using a specialized test method. Results help determine if your body handles glucose efficiently.

What the Results Mean

Results are compared to standard ranges to identify abnormal glucose levels. High results may indicate diabetes or insulin resistance, while normal results suggest good glucose control.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

This test is critical for diagnosing diabetes, assessing prediabetes risk, and monitoring long-term blood sugar management. It helps prevent complications like nerve damage, kidney disease, or heart disease by catching issues early.

Short name

2-Hour Glucose Test

Frequently asked questions

How often should I get this test?
Your doctor will determine the frequency based on your health status. For people with diabetes, tests may be done annually or more often if needed to adjust treatment.
What if I have questions about my results?
Always discuss your results with your healthcare provider. They can explain what the numbers mean in the context of your health and recommend next steps, such as lifestyle changes or medication adjustments.
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. Follow your doctor’s specific instructions 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