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Glucose, Serum (Concentration)

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

This test measures the amount of glucose, a type of sugar, in your blood serum. 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
32318-8
Short code
Glucose Spec-sCnc
Synonyms
Glucose Spec-sCnc
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 This Test Is Done

Doctors may order this test to check for diabetes or prediabetes, monitor blood sugar levels in people with diabetes, assess how well medications are working, or evaluate symptoms like excessive thirst, frequent urination, or unexplained weight changes.

What to Expect Before the Test

No special preparation is needed for this test. You may have a small needle inserted into a vein in your arm, and a small amount of blood will be drawn. This usually takes a few minutes.

What the Test Results Mean

Results help doctors diagnose conditions like diabetes, check for low blood sugar (hypoglycemia), or assess how well your body is managing glucose. Exact values can vary based on lab methods and may not be provided if your doctor has already interpreted them.

Common Reasons for Abnormal Results

High glucose levels may indicate diabetes or other metabolic issues, while low levels could signal hypoglycemia, stress, or certain medications. Your doctor will discuss these findings with you based on your overall health.

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

Glucose Level (Serum)

Frequently asked questions

What causes blood glucose levels to be tested regularly?
Regular testing is often recommended for people with diabetes, those at risk for diabetes, or individuals experiencing symptoms like frequent urination, extreme thirst, or unexplained weight changes.
How often should someone with diabetes check their blood glucose?
The frequency depends on your diabetes management plan, but doctors may recommend daily or multiple times a day checks, especially if you’re using insulin or other medications that affect blood sugar.
Can diet or exercise affect the results of this test?
Yes, diet and exercise can influence blood glucose levels. If you’ve recently eaten, exercised, or taken medications, your doctor may ask you to wait or adjust your timing before the test.
  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