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Glucose in Serum or Plasma (Mass Concentration)

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

This test measures the amount of glucose, a type of sugar, in your blood serum or plasma. Glucose is your body’s main source of energy.

Quick summary

["Your blood sugar levels help determine how your body uses food for energy and how well your organs are functioning."]

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

Key facts at a glance

LOINC
55505-2
Short code
GH 30M p Glc SerPl-mCnc
Synonyms
GH 30M 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

Doctors may order a serum or plasma glucose test to check for diabetes, monitor blood sugar levels in people with diabetes, evaluate symptoms like excessive thirst or fatigue, or assess conditions affecting metabolism.

What to Expect Before the Test

No special preparation is needed, but you may be asked to fast (not eat or drink) for 8–12 hours before the test if checking for diabetes-related conditions. Bring any medications you’re taking.

How the Test Is Performed

A healthcare provider will draw blood from a vein in your arm using a small needle. You may feel a slight prick, but it usually doesn’t cause pain. The blood is sent to a lab for analysis.

What the Results Mean

Results are typically reported in milligrams per deciliter (mg/dL) or millimoles per liter (mmol/L). Your doctor will interpret the results based on your medical history and symptoms.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

Clinical Significance

Short name

Serum/Plasma Glucose

Frequently asked questions

High glucose levels may indicate diabetes or other metabolic disorders, while low levels could signal conditions like hypoglycemia or liver/kidney issues. Regular monitoring helps manage long-term health risks.
This test is quick and usually done in a doctor’s office or lab. The blood sample is analyzed immediately or sent to a lab for processing within hours.
If you have diabetes, your doctor may recommend checking glucose levels at home using a blood glucose monitor, but lab tests provide more detailed results for medical decisions.
Yes, you may experience mild bruising, swelling, or discomfort at the injection site, but these are usually temporary. If you have a bleeding disorder or are on blood-thinning medication, let your doctor know.
Glucose tests can sometimes be affected by recent exercise, illness, or certain medications. If you’re unsure about your test results, discuss them with your healthcare provider.
No, glucose tests are not the same as hemoglobin A1c tests, which measure average blood sugar over the past 2–3 months. Both are important for diabetes management.
  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