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Glucose, Serum (Mass Concentration)

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

This test measures the amount of glucose (sugar) in your blood drawn from a vein in your arm. It helps doctors check how well your body is using sugar for energy and managing conditions like diabetes.

Quick summary

["A glucose test helps monitor blood sugar levels and identify diabetes or other metabolic issues."]

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

Key facts at a glance

LOINC
92817-6
Short code
Glucose 30M p Gc SerPl-mCnc
Synonyms
Glucose 30M p Gc 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 This Test Matters

Glucose is the primary energy source for your body’s cells. High or low levels can cause serious health problems, including nerve damage, heart disease, or even coma. This test helps prevent complications by tracking your blood sugar over time.

How the Test Works

A small sample of your blood is taken and sent to a lab. Special equipment then measures the glucose concentration using an enzymatic method, which detects the sugar’s presence without mixing it with other substances.

What to Expect Before the Test

You may be asked to fast (not eat or drink except water) for 8–12 hours before the test, depending on your doctor’s instructions. If you’re pregnant, have diabetes, or take certain medications, let your provider know beforehand.

Common Causes of Abnormal Results

Elevated glucose levels may occur due to diabetes, stress, illness, or poor diet. Low levels can happen from extreme exercise, insulin reactions, or certain medications. Your doctor will discuss results in the context of your health history.

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 did my doctor order this test?
Your doctor may recommend it to check for diabetes, high blood sugar, or low blood sugar. It’s often used in routine check-ups, during pregnancy, or if you have symptoms like excessive thirst, fatigue, or frequent urination.
What do my results mean?
Results alone don’t tell the full story. Your doctor will compare them to your symptoms, medical history, and other tests. They’ll explain what your specific numbers mean for your health.
Can I eat or drink before the test?
Follow your doctor’s instructions carefully. Typically, fasting is required, but some tests allow water. Never eat or drink anything else unless directed otherwise.
  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