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Glucose (Serum)

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

This test measures the amount of glucose, a type of sugar, in your blood serum. It helps doctors assess how well your body is managing energy from food.

Quick summary

["This test helps track blood sugar control and identify potential issues like diabetes or hypoglycemia."]

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

Key facts at a glance

LOINC
32359-2
Short code
Glucose 10M p Glc SerPl-sCnc
Synonyms
Glucose 10M p Glc 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?

Your doctor may order this test to check for conditions like diabetes, monitor blood sugar levels over time, or evaluate how your body responds to treatments for blood sugar issues. It’s also used in screening for prediabetes or to assess metabolic health.

What to Expect Before the Test

No special preparation is needed for this test. You may fast (not eat) for 8–12 hours before the test if it’s part of a fasting glucose check, but if it’s a routine serum glucose test, eating normally is fine. Bring any medications you’re taking to your appointment.

What Happens During the Test?

A healthcare provider will draw blood from a vein in your arm using a small needle. You may feel a slight pinch, but it usually doesn’t cause much discomfort. The blood sample is then sent to a lab for analysis.

What Does the Test Result Mean?

Results are typically reported in milligrams per deciliter (mg/dL) or millimoles per liter (mmol/L). While reference ranges vary by lab, high or low glucose levels can signal diabetes, hypoglycemia, or other metabolic concerns. Your doctor will interpret the result in the context of your overall health.

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

How often should I get this test?
The frequency depends on your health status. If you have diabetes, your doctor may recommend testing every few months to a year. If you’re healthy or at low risk, routine testing may not be necessary unless advised by your provider.
What can affect my glucose test results?
Factors like recent meals, exercise, stress, certain medications, or illness can influence results. If you’re unsure, tell your doctor about any changes in diet, activity, or medications before the test.
Do I need to fast for this test?
Only if your doctor specifies a fasting glucose test (e.g., for diabetes screening). For a general serum glucose test, fasting isn’t required unless instructed 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