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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.

Quick summary

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

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

Key facts at a glance

LOINC
81324-6
Short code
GTT gest 2h Pnl SerPl
Synonyms
GTT gest 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 Is Done

Your doctor may order this test if you have symptoms of diabetes, such as frequent urination, excessive thirst, or unexplained weight changes. It can also help diagnose conditions like reactive hypoglycemia or evaluate how well diabetes medications are working.

What to Expect Before the Test

You’ll need to fast overnight (usually 8–12 hours) before the test. On the day of the test, you’ll eat a standard meal, and your blood will be drawn two hours later for testing.

How the Test Works

A small needle is used to draw blood from a vein in your arm. The sample is sent to a lab where glucose levels are measured using an automated method.

What the Results Mean

Results help determine if your blood sugar is within a healthy range after eating or if further management is needed. Abnormal results may prompt additional testing or lifestyle adjustments.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

This test is critical for diagnosing or monitoring conditions related to blood sugar control, such as diabetes or metabolic disorders. High levels may indicate poor glucose tolerance, while consistently low levels could signal reactive hypoglycemia or other metabolic issues.

Short name

2h Glucose

Frequently asked questions

What causes false high or low results in this test?
False results can occur if you didn’t fast properly, ate unusual foods, or had recent physical activity. Always follow your doctor’s instructions for preparation.
How often should I get this test?
Your doctor will determine the frequency based on your health status, but typically, it’s done annually or more often if you have diabetes or other related conditions.
Can I take my diabetes medication before the test?
Yes, but always check with your doctor first. Some medications may affect blood sugar levels, so they may adjust your dose or timing for the test.
  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