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Glucose, Serum (Mass Concentration)

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

This test measures the amount of glucose (sugar) in your blood drawn from a vein in your arm. It helps doctors assess how well your body is using sugar for energy and check for conditions like diabetes or low blood sugar.

Quick summary

["This test helps monitor blood sugar levels and identify potential diabetes or hypoglycemia."]

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

Key facts at a glance

LOINC
26539-7
Short code
Glucose 45M p Glc SerPl-mCnc
Synonyms
Glucose 45M p Glc 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, low blood sugar (hypoglycemia), or to check for other metabolic issues. It may also be used during pregnancy, before surgeries, or to evaluate symptoms like excessive thirst, frequent urination, or unexplained weight changes.

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 blood sugar check. Wear comfortable clothing and bring any medications you’re currently taking.

What Happens During the Test?

A healthcare professional will insert a small needle into a vein in your arm to draw blood. You may feel a slight pinch, but it usually doesn’t cause pain. The blood sample is then sent to a lab for analysis.

What to Expect After the Test

You may experience mild bruising, swelling, or discomfort at the injection site, which usually goes away within a few hours. Apply a cold compress if needed. Avoid heavy lifting or strenuous activity for a short time to prevent excessive bleeding.

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.

◆Associated findings1

Short name

Serum Glucose

Frequently asked questions

How often should I expect to have this test?
The frequency depends on your health condition. If you have diabetes, your doctor may recommend testing every few months or annually. Others may need it less often, such as once a year for routine checks or during pregnancy.
Will fasting affect my results?
Yes, fasting (not eating for 8–12 hours) can give a more accurate measure of your blood sugar levels, especially if your doctor is checking for diabetes or hypoglycemia. If you have a non-fasting test, your results may be less reliable for diagnosing these conditions.
What if my results are outside the normal range?
If your results are high, your doctor may recommend lifestyle changes (like diet and exercise), medications, or further testing. If low, they may suggest dietary adjustments, monitoring for symptoms, or medical treatment if needed. Always discuss your results with your healthcare provider.
  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