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Glucose in Serum or Plasma (24-Hour Profile)

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

This test measures your blood glucose levels over a 24-hour period using a sample of your serum or plasma.

Quick summary

["Understanding your glucose levels throughout the day helps identify patterns in blood sugar control."]

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

Key facts at a glance

LOINC
47777-8
Short code
GH pre Ins IV SerPl-aCnc
Synonyms
GH pre Ins IV SerPl-aCnc
Category
hormone
Sample
serum
Container
Red-top tube (SST)
Units
N/A
Fasting
false
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 Is Done

Your healthcare provider may order this test if you have diabetes, prediabetes, or symptoms like frequent urination, excessive thirst, or unexplained weight changes. It can also help assess how well your body manages glucose, especially if you take medications or have conditions like kidney disease.

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. Bring any medications you’re currently taking to your appointment.

During the Test

A healthcare professional will draw blood from a vein in your arm. You may feel a slight pinch, but the procedure is quick. The sample is then processed to measure glucose levels at multiple time points (typically every few hours).

What the Results Mean

Results show your glucose levels at different times of the day. Abnormal patterns may indicate poor glucose control, insulin resistance, or other metabolic issues. Your provider will interpret these results in the context of your overall health.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

Clinical Significance

Frequently asked questions

How often should I get this test?
Does this test require fasting?
Sometimes yes, but not always. If your provider specifies a fasting profile, you’ll need to avoid food/drinks (except water) for 8–12 hours before. Always follow their instructions to get accurate results.
What if my glucose levels are high or low?
High levels may signal diabetes or poor management of medications. Low levels (hypoglycemia) can cause dizziness, shakiness, or confusion. Your provider will discuss lifestyle or treatment adjustments based on your results.
No, if fasting is required. If not, you can eat normally, but avoid sugary foods/drinks that might skew results. Ask your provider for clarification before your appointment.
  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