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Glucose, Serum or Plasma (Mass Concentration)

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

This test measures the amount of glucose, a type of sugar, in your blood. It helps assess how well your body is using glucose for energy and managing blood sugar levels.

Quick summary

["Glucose levels help diagnose diabetes, monitor treatment, or check for conditions affecting blood sugar."]

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

Key facts at a glance

LOINC
40001-0
Short code
Glucose 5M p chal SerPl-mCnc
Synonyms
Glucose 5M p chal 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 check for diabetes or prediabetes, evaluate symptoms like excessive thirst or fatigue, monitor blood sugar control in people with diabetes, or assess conditions like hypoglycemia (low blood sugar). It can also be used during pregnancy to screen for gestational diabetes.

What to Expect Before the Test

For blood tests, you’ll typically have a small needle inserted into your arm to draw blood. If you’re fasting (not eating or drinking except water), your provider will instruct you to avoid food for 8–12 hours beforehand. For plasma/serum tests, you may be asked to sit quietly while blood is collected.

What the Results Mean

Results are compared to general reference ranges, but individual needs vary. High glucose levels may indicate diabetes or other metabolic issues, while very low levels could signal hypoglycemia or other health problems. Your provider will discuss results in the context of your overall health.

Common Reasons for Abnormal Results

Elevated glucose levels might be due to diabetes, stress, illness, or certain medications. Low levels could result from excessive exercise, certain foods, or medical conditions like adrenal insufficiency. Always discuss any concerns with your healthcare team.

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

Frequently asked questions

Why might my glucose test be done at this time?
Your provider may have noted symptoms like frequent urination, unexplained weight changes, or fatigue, or may suspect diabetes, prediabetes, or another blood sugar-related condition. It could also be part of routine screening or monitoring for a known health issue.
What does a ‘fasting’ glucose test mean?
A fasting test means you’ll avoid eating or drinking (except water) for a set period before the blood draw to get a more accurate reading of your baseline blood sugar levels. This helps identify if your body struggles to regulate glucose properly.
Can I eat or drink anything before this test?
For fasting tests, you’ll need to stop eating solids and liquids (except water) for 8–12 hours before the test. If your provider says otherwise, follow their instructions. Non-fasting tests may allow small amounts of water or clear liquids, but always confirm with your lab or 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