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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. It helps doctors assess how your body manages glucose, especially if you have or are at risk for diabetes or other metabolic conditions.

Quick summary

["Understanding how your body naturally regulates blood sugar over time can help prevent complications like high blood pressure or nerve damage."]

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

Key facts at a glance

LOINC
40309-7
Short code
GH pre/p Glc SerPl-mCnc
Synonyms
GH pre/p Glc SerPl-mCnc
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 Is Done

Your doctor may order this test if they suspect you have diabetes, prediabetes, or another condition affecting blood sugar control. It can also be used to monitor treatment effectiveness or check for hidden issues like insulin resistance or reactive hypoglycemia.

What to Expect Before the Test

You’ll typically fast (not eat or drink) for 8 to 12 hours before the test. Blood is drawn from a vein in your arm at set times over 24 hours. Your doctor or nurse will guide you on when to take samples and what to avoid during this period.

How the Test Works

Blood samples are collected at specific intervals (often every 2–4 hours) and tested for glucose concentration using a sensitive laboratory method. The results help create a profile of your blood sugar levels throughout the day.

What the Results Mean

While individual ranges vary, abnormal patterns (like consistently high or low glucose) may indicate diabetes, hormonal imbalances, or other health concerns. Your doctor will compare your results to your body’s natural fluctuations and medical history to interpret them.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

◆Associated findings1

Short name

24-Hour Glucose Profile

Frequently asked questions

How often is this test typically done?
This test is usually done once, but your doctor may recommend repeating it if they suspect ongoing issues with blood sugar control or if you’re undergoing treatment for a metabolic condition.
What should I do if I feel dizzy or weak during blood draws?
Tell your healthcare provider immediately if you experience dizziness, nausea, or other symptoms. They may adjust your position, give you a small sip of water, or pause the procedure to ensure your safety.
Can I take my usual medications before the test?
Yes, but follow your doctor’s instructions carefully. Some medications (like insulin or diabetes medications) may need to be adjusted or temporarily paused. Never stop taking them without approval.
  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