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Glucose in Serum or Plasma (24-Hour Urine Collection)

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

This test measures the amount of glucose (sugar) in your blood or urine over a 24-hour period, often used to assess how well your body manages blood sugar levels.

Quick summary

["Helps diagnose or monitor conditions like diabetes or abnormal sugar metabolism."]

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

Key facts at a glance

LOINC
47771-1
Short code
GH 3h p Glc PO SerPl-aCnc
Synonyms
GH 3h 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 Is This Test Done?

Your doctor may order this test to check for diabetes, prediabetes, or other conditions affecting blood sugar. A 24-hour urine collection helps detect hidden sugar loss in urine, which can occur in certain metabolic disorders.

How Is the Test Performed?

For blood/serum/plasma: A blood sample is taken from a vein, usually in your arm. For urine: You’ll collect all urine over 24 hours in a special container. Follow your healthcare provider’s instructions carefully to ensure accurate results.

What to Expect Before the Test

No special preparation is needed for blood tests, but for urine tests, avoid high-sugar foods/drinks for the collection period. Drink enough fluids to maintain normal urine output.

What the Results Mean

Results show the average glucose concentration in your blood or urine over 24 hours. Elevated levels may indicate diabetes or other metabolic issues, while normal results suggest healthy glucose regulation.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

◆Associated findings1

Frequently asked questions

What causes false high or low results?
False high results may occur if you didn’t follow urine collection instructions (e.g., missed samples) or consumed sugary foods/drinks. False low results are less common but could happen if urine was diluted or improperly stored.
How often should I get this test?
Your doctor will determine frequency based on your health status. People with diabetes typically check every 3–6 months, while others may need it less often.
Can I eat or drink before the blood test?
For blood tests, you can eat normally unless instructed otherwise. For urine tests, avoid sugary foods/drinks during the 24-hour collection period.
  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