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Glucose, Serum or Plasma Concentration

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

This test measures the amount of glucose (sugar) in your blood, typically taken from a serum or plasma sample.

Quick summary

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

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

Key facts at a glance

LOINC
32319-6
Short code
Glucose 30M p 75 g Glc PO SerPl-sCnc
Synonyms
Glucose 30M p 75 g Glc PO SerPl-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 Is This Test Done?

Doctors order glucose tests to check for diabetes, monitor blood sugar control, diagnose metabolic disorders, or assess symptoms like excessive thirst, fatigue, or unexplained weight changes.

When Might You Need This Test?

You may need this test if you have symptoms of high or low blood sugar, if you’re diagnosed with diabetes, or if your doctor wants to track how well your current treatments are working.

What to Expect Before the Test

For a blood draw, you’ll likely fast (not eat) for 8–12 hours before the test, unless your doctor instructs otherwise. A healthcare provider will insert a small needle into your arm to collect a blood sample.

What Happens During the Test?

The blood sample is sent to a lab, where it’s analyzed to measure glucose concentration using an automated method, often an enzymatic assay.

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.

High or low blood sugar can cause serious health issues, including nerve damage, heart disease, kidney problems, or even coma in severe cases. Regular monitoring helps prevent long-term complications and guides treatment decisions.

Short name

Glucose Level

Frequently asked questions

What causes abnormal glucose levels?
Abnormal results may be due to diabetes, poor diet, stress, illness, certain medications, or underlying conditions like thyroid disorders. Your doctor will discuss results and next steps with you.
How do I prepare for this test?
Follow fasting instructions (usually 8–12 hours before testing) and avoid smoking or caffeine. Wear loose clothing for the blood draw if needed. Ask your doctor about any medications to temporarily pause.
What do my results mean?
Results are compared to your doctor’s expectations based on your health history. They may suggest lifestyle changes, medication adjustments, or further testing if needed. Never interpret results alone—always discuss them with your 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