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Glucose in Serum or Plasma (24-Hour Average)

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

This test measures the average blood sugar level over a 24-hour period using a sample of your serum or plasma.

Quick summary

["Understanding your typical blood sugar helps manage diabetes and other conditions affecting glucose metabolism."]

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

Key facts at a glance

LOINC
11938-8
Short code
GA from rad len
Synonyms
GA from rad len
Category
chemistry
Sample
serum
Container
Red-top tube (SST)
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
Method
us-estimated-from-radius-length
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 to assess long-term blood sugar control, especially if you have diabetes or are at risk for complications like nerve damage or kidney issues. It can also help monitor how well your current treatment plan is working.

How the Test Works

A small blood sample is taken, and the glucose levels are measured using a specialized method that calculates the average over 24 hours based on your body’s natural fluctuations.

What to Expect Before the Test

No special preparation is needed, but you may be asked to fast for 8–12 hours before the test if it’s part of a fasting profile. Wear comfortable clothing for blood draws.

What to Expect During the Test

A healthcare professional will insert a small needle into your arm to draw blood. You may feel a slight pinch, but the process usually takes just a few minutes. The sample is then sent to a lab for analysis.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

◆Associated findings1

Frequently asked questions

How often should I get this test?
The frequency depends on your health condition. People with diabetes typically get this test every 3–6 months, while others may need it less often or only if symptoms arise.
Does fasting affect this test?
No, this test measures your average glucose regardless of fasting status. However, if it’s part of a fasting profile, fasting may be required for other tests in the panel.
What do the results mean if they’re outside my usual range?
If results are consistently high, your provider may recommend lifestyle changes, medication adjustments, or further testing to identify underlying causes. If low, they may investigate potential causes like medication side effects or insulin overuse.
  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