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Glucose, measured as mass concentration in serum/plasma

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

This test checks the amount of glucose (sugar) in your blood, typically drawn from a vein or fingerstick.

Quick summary

["Glucose levels help monitor blood sugar and identify diabetes or other metabolic conditions."]

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

Key facts at a glance

LOINC
58857-4
Short code
GH sp9 SerPl-mCnc
Synonyms
GH sp9 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 Is This Test Done?

Your healthcare provider may order this test to check for diabetes, monitor blood sugar levels, diagnose conditions like hypoglycemia, or assess how your body processes glucose. It’s also used in routine check-ups or before certain treatments.

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 blood sugar panel. If fasting isn’t required, eat a normal meal the day of the test.

How the Test Works

A healthcare professional will draw blood from your arm or use a small needle on your finger. The blood is sent to a lab where glucose levels are measured using an automated method, often involving chemical reactions or specialized instruments.

What the Results Mean

Results are usually reported in milligrams per deciliter (mg/dL) or millimoles per liter (mmol/L). High or low levels may signal diabetes, prediabetes, or other health concerns that need further evaluation.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

◆Associated findings1

Short name

Serum/Plasma Glucose

Frequently asked questions

What causes my glucose levels to be high or low?
High glucose can result from diabetes, stress, illness, or poor diet. Low glucose (hypoglycemia) may occur from excessive insulin, skipping meals, or certain medications. Lifestyle factors like exercise or alcohol also play a role.
Do I need to do anything special after the test?
You can resume normal activities immediately unless your provider instructed otherwise. If you had fasting required, you can eat a normal meal once the test is complete.
Will I always need to check my glucose levels at home?
Not everyone needs home monitoring. If you have diabetes, your provider may recommend self-testing with a glucose meter for daily management. Others may only need lab tests periodically.
  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