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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 drawn from a vein or collected in a tube.

Quick summary

["Your blood sugar levels help manage energy and prevent complications like diabetes."]

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

Key facts at a glance

LOINC
40302-2
Short code
GH pre Arg SerPl-mCnc
Synonyms
GH pre Arg SerPl-mCnc
Category
chemistry
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

Doctors may order this test to check for diabetes, monitor blood sugar control in people with diabetes, diagnose conditions like hypoglycemia (low blood sugar), or evaluate metabolic health. It’s also used during pregnancy to screen for gestational diabetes.

What to Expect Before the Test

You may be asked to fast (not eat) for 8–12 hours before the test, especially if it’s a fasting glucose check. Bring any medications you’re taking and let your provider know if you have any allergies or conditions.

During the Test

A healthcare professional will insert a small needle into your arm to draw blood. You may feel a brief pinch, but it’s usually over quickly. If you’re nervous, ask about numbing cream or other options.

After the Test

You can resume normal activities immediately. Apply gentle pressure to the site to stop bleeding, and check for any redness or swelling. Report any severe pain or signs of infection right away.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

This test is critical for diagnosing and managing blood sugar disorders. High or low glucose levels can lead to serious health risks, including nerve damage, heart disease, or frequent infections. Regular monitoring helps prevent long-term complications.

Short name

Serum/Plasma Glucose

Frequently asked questions

What does a high or low blood sugar mean?
High glucose levels may indicate diabetes or poor control of pre-existing diabetes. Low levels can cause dizziness, shakiness, or confusion. Your doctor will discuss results and next steps with you.
Do I need to prepare differently if I’m pregnant?
Yes, some pregnant women get a glucose screening between 24–28 weeks to check for gestational diabetes. Follow your doctor’s instructions, which may include fasting or a glucose challenge test.
Can I eat or drink anything before this test?
For fasting tests, avoid food and liquids (except water) for 8–12 hours. For non-fasting tests, eat normally, but inform your provider if you’re unsure.
  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