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Glucose in Blood (Serum or Plasma)

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

This test measures the amount of glucose, a type of sugar, in your blood. It helps assess your blood sugar levels and supports the diagnosis or monitoring of conditions like diabetes.

Quick summary

["This test checks your blood sugar levels to help manage health conditions related to glucose metabolism."]

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

Key facts at a glance

LOINC
39480-9
Short code
Glucose BldV-sCnc
Synonyms
Glucose BldV-sCnc
Category
glucose
Sample
whole-blood
Container
Lavender-top (EDTA)
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
3 mL
Stability
Room temperature: 4h, Refrigerated: 24h
Hemolysis max
0
Lipemia max
0
Icterus max
0
TAT
4–24 hours
Order
routine

Why This Test Is Done

Your healthcare provider may order this test to diagnose or monitor diabetes, check for high or low blood sugar, evaluate symptoms like excessive thirst or fatigue, or assess how your body responds to treatments like insulin or medications.

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 study. Otherwise, you can eat and drink normally.

How the Test Is Performed

A small blood sample is drawn from a vein in your arm using a needle. The sample is then sent to a lab where it’s analyzed to measure glucose concentration.

Possible Results and Interpretation

Results are compared to standard reference ranges, but your actual values will be interpreted by your healthcare provider based on your medical history, symptoms, and other factors.

Reference range

Fasting: 70-100 mg/dLN/A

Specimen: whole-blood

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.

High blood glucose levels can indicate diabetes or prediabetes, while persistently low levels may signal conditions like hypoglycemia. Regular monitoring helps prevent complications like nerve damage, kidney disease, or heart problems.

Short name

Blood Glucose

Frequently asked questions

What causes blood glucose levels to be tested?
Blood glucose tests are often done to check for diabetes, monitor diabetes management, or investigate symptoms like unexplained weight loss, frequent infections, or unusual thirst.
How often should I get this test?
Frequency depends on your health status. People with diabetes typically get tests every few months, while others may need them less often or only when symptoms arise.
Can diet or exercise affect my test results?
Yes—fasting before a test can impact results, and eating or drinking certain foods (like sugary drinks) right before can temporarily raise or lower glucose levels.
  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