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Glucose, Serum or Plasma (Quantitative)

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

This test measures the amount of glucose (sugar) in your blood, typically taken from serum or plasma. It helps monitor blood sugar levels, often used in diabetes management or during pregnancy.

Quick summary

["A glucose test checks your blood sugar, important for managing health conditions like diabetes."]

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

Key facts at a glance

LOINC
1530-5
Short code
Glucose 3h p 100 g Glc PO SerPl-mCnc
Synonyms
Glucose 3h p 100 g Glc PO SerPl-mCnc
Category
glucose
Sample
serum
Container
Red-top tube (SST)
Units
N/A
Ref low
70
Ref high
100
Critical range
50 N/A – 400 N/A
Fasting
true
Population
adult
Sex
all
Age range
18–65 years
CPT
82947
SNOMED
260395008
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 diagnose or monitor conditions such as diabetes, high blood sugar, hypoglycemia, or to check for metabolic issues. It may also be done during pregnancy to screen for gestational diabetes or before certain surgeries.

What to Expect Before the Test

No special preparation is usually needed, but you may be asked to fast (not eat or drink anything except water) for 8–12 hours before the test if it’s part of a fasting glucose check. If you’re pregnant or have specific health conditions, follow your provider’s instructions.

How the Test Is Done

A healthcare professional will draw blood from a vein in your arm using a small needle. You may feel a slight pinch, but the procedure is quick and usually painless. The blood sample is sent to a lab for analysis.

What the Results Mean

Results are reported as a mass concentration of glucose in milligrams per deciliter (mg/dL) or millimoles per liter (mmol/L). While reference ranges vary by lab, lower or higher than expected levels may signal diabetes, prediabetes, or other health concerns. Your provider will interpret results in the context of your medical history.

Reference range

Fasting: 70-100 mg/dLN/A

Specimen: serum

Fasting for 8-12 hours required. Water is permitted. Avoid chewing gum and smoking before the test.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

Clinical Significance

Short name

Glucose Level

Frequently asked questions

How often should I get this test?
The frequency depends on your health status. People with diabetes typically check glucose levels regularly, while others may get it less often—such as during routine checkups or if symptoms like extreme thirst, fatigue, or frequent urination appear.
What if my results are abnormal?
If your glucose levels are outside the expected range, your provider may recommend further testing (like an oral glucose tolerance test) or adjustments to your treatment plan, such as diet, exercise, or medication.
Can I eat or drink anything before this test?
For fasting tests, avoid food and most liquids (except water) for 8–12 hours beforehand. If your test isn’t fasting-related, follow your provider’s specific instructions to ensure accurate results.
  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