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Glucose in Serum or Plasma (Mass Concentration)

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

This test measures the amount of glucose (sugar) in your blood drawn from a vein or collected in a tube.

Quick summary

["Your blood sugar levels help monitor diabetes or other conditions affecting glucose metabolism."]

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

Key facts at a glance

LOINC
35211-2
Short code
Glucose SerPl-msCnc
Synonyms
Glucose SerPl-msCnc
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 order this test to check for diabetes, monitor blood sugar control in people with diabetes, detect high or low blood sugar, or evaluate conditions like hypoglycemia or hyperglycemia. It may also be used to assess metabolic health or screen for prediabetes.

What to Expect Before the Test

You may be asked to fast (not eat) for 8–12 hours before the test, though some centers allow small sips of water. A healthcare provider will insert a needle into your arm to draw blood. You may feel a brief pinch, but it’s usually over quickly.

What the Results Mean

Results are typically reported in milligrams per deciliter (mg/dL) or millimoles per liter (mmol/L). Abnormal results may trigger further testing or adjustments to medication, diet, or activity levels.

Common Causes of Abnormal Results

High glucose levels can result from diabetes, stress, illness, or poor diet. Low levels may occur from fasting, certain medications, or insulin reactions. Symptoms like fatigue, blurred vision, or shakiness may accompany either condition.

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/Plasma Glucose

Frequently asked questions

How often should I get this test?
The frequency depends on your health. People without diabetes may get it once every few years for routine checks. Those with diabetes typically test monthly or quarterly, as recommended by their doctor.
What can affect my test results?
Fasting status (eating or drinking before testing), stress, illness, certain medications (like steroids or beta-blockers), or recent exercise can influence results. Always follow your provider’s instructions precisely.
Do I need to prepare differently if I’m pregnant?
Yes, pregnant women may need to fast longer or test at different times (e.g., after breakfast). Your doctor will guide specific preparations to ensure accurate results for both you and your baby.
  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