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Glucose measured 3 hours post-glucose challenge in plasma

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

This test evaluates your blood sugar level three hours after drinking a glucose solution, often used to assess how your body processes glucose over time.

Quick summary

["Helps diagnose conditions like diabetes or how your pancreas responds to sugar intake."]

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

Key facts at a glance

LOINC
102022-1
Short code
Glucose 3h p Gc SerPl-mCnc
Synonyms
Glucose 3h p Gc SerPl-mCnc
Category
glucose
Sample
serum
Container
Red-top tube (SST)
Units
N/A
Ref low
70
Ref high
100
Critical range
50 N/A – 400 N/A
Fasting
true
Population
adult
Sex
all
Age range
18–65 years
CPT
82947
SNOMED
260395008
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 Is This Test Done?

Doctors may order this test if you have symptoms of high blood sugar (like frequent urination, extreme thirst, or fatigue) or if you’re being evaluated for diabetes, prediabetes, or other metabolic conditions. It helps track how well your body manages glucose after consuming a sugary drink.

What to Expect Before the Test

You’ll drink a sweet liquid (glucose solution) and then fast for about 3 hours. Blood is drawn from your arm at the 3-hour mark to check your glucose level. No special preparation is needed beyond fasting.

What Happens During the Test?

A healthcare provider will take a small blood sample from your vein. You may feel a slight pinch, but it’s quick. The test measures your plasma glucose concentration, which reflects how your body handles sugar.

What the Results Mean

Results help doctors determine if your blood sugar is consistently high or low, which can indicate diabetes, insulin resistance, or other metabolic disorders. Your doctor will compare these results to your overall health and other tests.

Reference range

Fasting: 70-100 mg/dLN/A

Specimen: serum

Fasting for 8-12 hours required. Water is permitted. Avoid chewing gum and smoking before the test.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

◆Associated findings1

Short name

3-Hour Plasma Glucose (Post-Challenge)

Frequently asked questions

Why did my doctor ask for this test?
Your doctor may have suspected diabetes, prediabetes, or another metabolic issue based on symptoms like frequent urination, unexplained weight changes, or family history. This test helps confirm how your body processes glucose over time.
What does a high or low result mean?
A high result may indicate diabetes or poor glucose tolerance, while a low result could suggest hypoglycemia (low blood sugar) or other conditions. Your doctor will discuss results in the context of your health and other tests.
Can I eat or drink anything before this test?
Yes, you can eat a normal meal before the test, but you must fast (no food or drink except water) for about 3 hours before your blood is drawn.
  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