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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 blood serum or plasma.

Quick summary

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

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

Key facts at a glance

LOINC
47765-3
Short code
GH 2h p Glc PO SerPl-aCnc
Synonyms
GH 2h p Glc PO SerPl-aCnc
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

Measuring average glucose over 24 hours provides a clearer picture of how your body handles blood sugar compared to a single point-in-time reading. This can help doctors assess long-term control of conditions like diabetes.

How the Test Works

Your blood sample is analyzed to determine the concentration of glucose in your bloodstream. The test uses a specialized method to estimate the average level over a full day, often derived from continuous glucose monitoring data or specific biochemical assays.

What to Expect Before the Test

No special preparation is needed for this test. You may have a simple blood draw, similar to other blood tests. If your doctor uses a 24-hour average derived from continuous monitoring, you might need to follow specific instructions regarding diet, activity, or monitoring devices.

What the Results Mean

Results are typically expressed as an average concentration over 24 hours. While exact reference ranges vary by lab, higher-than-normal averages may indicate poor blood sugar control, while lower-than-normal averages might suggest hypoglycemia or other metabolic issues.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

◆Associated findings1

Frequently asked questions

What causes abnormal results?
Abnormal results may be due to conditions like diabetes (both type 1 and type 2), hormonal imbalances, liver or kidney disease, or certain medications. Poor diet, stress, or physical activity can also temporarily affect glucose levels.
How often should I get this test?
Your doctor will determine the frequency based on your health condition, treatment plan, and response to therapy. Regular monitoring helps track progress and adjust care as needed.
Can I fast before this test?
No fasting is required for this test, as it measures average glucose levels over 24 hours. However, follow your doctor’s instructions if using continuous glucose monitoring data, as some methods may require fasting or specific dietary restrictions.
  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