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Glucose in Serum (Predose, 24-Hour Average)

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

This test measures your average blood sugar levels over the past 24 hours, specifically before meals. It helps assess how well your body manages glucose (sugar) over time.

Quick summary

["Understanding your body’s natural glucose balance before eating can help manage diabetes or other blood sugar-related conditions."]

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

Key facts at a glance

LOINC
47935-2
Short code
GH pre dose GRF SerPl-aCnc
Synonyms
GH pre dose GRF SerPl-aCnc
Category
chemistry
Sample
serum
Container
Red-top tube (SST)
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
CPT
86430
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 glucose concentration in your blood before meals provides insight into how consistently your body regulates blood sugar. Unlike a single blood sugar reading, this test reflects your average levels over a full day, which is crucial for diagnosing conditions like diabetes or prediabetes and tailoring treatment plans.

What to Expect Before the Test

You’ll typically fast for 8 to 12 hours before this test. Your blood sample will be drawn from a vein, usually in your arm, and sent to a lab for analysis. The test is usually done in the morning after fasting.

How the Results Are Used

Your healthcare provider will use these results to check if your blood sugar levels are within a healthy range. If you have diabetes or are at risk, this test helps determine if your current treatment plan is effective or if adjustments are needed.

Common Causes for Testing

This test may be ordered if you have symptoms of high or low blood sugar, if you have diabetes or are at risk for it, or if your doctor wants to monitor how well your body manages glucose over time.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

◆Associated findings1

Frequently asked questions

What does a high or low average glucose level mean?
A high average glucose level may suggest poor blood sugar control, which could be linked to conditions like diabetes or insufficient management of your treatment plan. A low average glucose level might indicate hypoglycemia or an overactive response to medications or insulin.
How long will I need to fast before this test?
You’ll usually need to fast for 8 to 12 hours before this test. Your doctor or lab will provide specific instructions based on your situation.
Is there any preparation I need to do besides fasting?
Besides fasting, avoid eating, drinking anything but water, smoking, or exercising for the fasting period. Wear comfortable clothing and let your healthcare provider know about any medications you’re taking, especially those that affect blood sugar.
  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