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Glucose, 8-hour fasting plasma concentration

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

This test measures the amount of glucose (sugar) in your blood after fasting for 8 hours. It helps assess how well your body regulates blood sugar levels.

Quick summary

["This test helps check for conditions like diabetes or insulin resistance."]

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

Key facts at a glance

LOINC
54256-3
Short code
Glucose 8M p Gc SerPl-sCnc
Synonyms
Glucose 8M p Gc SerPl-sCnc
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 This Test Is Done

Your healthcare provider may order this test if you have symptoms of high or low blood sugar, such as excessive thirst, frequent urination, fatigue, or unexplained weight changes. It may also be used to monitor blood sugar control in people with diabetes or prediabetes.

How the Test Is Performed

A blood sample is taken from a vein, usually in your arm. The sample is collected in a special tube that prevents blood from clotting. The plasma portion is then analyzed for glucose concentration using an immunoassay method.

What to Expect Before the Test

You must fast (not eat or drink anything except water) for at least 8 hours before the test. Avoid smoking and consuming alcohol for at least 24 hours prior. Inform your provider about any medications you are taking, as some may affect blood sugar levels.

What to Expect During the Test

The test is quick and typically done in a clinic or lab setting. You may feel a small pinch when the needle is inserted, but it usually goes away quickly. You can resume normal activities immediately after.

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

8-Hour Fasting Plasma Glucose

Frequently asked questions

What does an abnormal result mean?
An abnormal result may mean your blood sugar levels are too high or too low for your body’s needs. Your healthcare provider will discuss your results with you and may recommend further testing or changes to your diet, exercise, or medication plan.
Can I eat or drink anything before this test?
No, you must fast for at least 8 hours before this test. Only water is allowed during this period. Always follow your provider’s instructions precisely.
How long will it take to get my results?
Results are typically available within a few days, depending on your lab’s processing time. Your healthcare provider will contact you to discuss the findings once they are ready.
  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