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Glucose (Serum/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. It helps assess how well your body is using glucose for energy and managing blood sugar levels.

Quick summary

["Glucose levels reflect your body’s ability to process sugar and maintain energy balance."]

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

Key facts at a glance

LOINC
1553-7
Short code
Glucose pre Ins IV SerPl-mCnc
Synonyms
Glucose pre Ins IV 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 Is Done

Doctors order glucose tests to check for conditions like diabetes, high or low blood sugar, or to monitor blood sugar control in people with diabetes. It may also be used during pregnancy, before surgeries, or to evaluate symptoms such as excessive thirst, frequent urination, or unexplained weight changes.

How the Test Is Performed

A healthcare provider will insert a needle into a vein in your arm to draw blood. You may feel a small prick, but it usually doesn’t cause pain. The blood sample is sent to a lab where it’s analyzed for glucose concentration.

What the Results Mean

Results are typically reported in milligrams per deciliter (mg/dL) or millimoles per liter (mmol/L). While exact reference ranges vary by lab, abnormal results may indicate diabetes, hypoglycemia, or other metabolic issues that need further evaluation.

Common Conditions Affecting Results

Factors like recent meals, physical activity, stress, or certain medications can temporarily affect glucose levels. For example, eating a high-carb meal before the test may raise blood sugar, while exercise could lower it.

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

What does a high glucose level mean?
A consistently high glucose level may signal diabetes or prediabetes, where your body struggles to regulate blood sugar. Repeatedly elevated results warrant follow-up with a healthcare provider to discuss treatment options, such as lifestyle changes or medication.
What does a low glucose level mean?
Low glucose (hypoglycemia) can cause symptoms like shakiness, dizziness, or confusion. If you experience these symptoms, especially after eating, inform your doctor immediately. Severe cases may require immediate medical attention.
How often should I get this test?
Your doctor will determine the frequency based on your health status. For example, people with diabetes may need tests every few months, while others may only need them once annually or as needed for monitoring symptoms.
  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