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Glucose, Serum 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 assess how well your body is using sugar for energy and managing blood sugar levels.

Quick summary

["Your blood sugar levels can tell doctors if you have diabetes or other health concerns."]

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

Key facts at a glance

LOINC
51596-5
Short code
Glucose BldC-sCnc
Synonyms
Glucose BldC-sCnc
Category
glucose
Sample
whole-blood
Container
Lavender-top (EDTA)
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
3 mL
Stability
Room temperature: 4h, Refrigerated: 24h
Hemolysis max
0
Lipemia max
0
Icterus max
0
TAT
4–24 hours
Order
routine

Why Is This Test Done?

Doctors may order this test to check for diabetes, monitor blood sugar levels in people with diabetes, diagnose conditions like hypoglycemia (low blood sugar), or evaluate metabolic health. It’s also used during pregnancy to screen for gestational diabetes.

How Is the Sample Collected?

A healthcare provider will clean your arm with an antiseptic, insert a small needle into your vein, and collect blood into a tube. The needle is removed once the sample is gathered. You may feel a brief pinch or sting, but it usually doesn’t cause long-lasting discomfort.

What Should You Expect Before the Test?

If you’re fasting (not eating or drinking anything except water) for this test, follow your doctor’s instructions carefully. Avoid caffeine or sugary drinks before the draw. If you’re not fasting, eat a normal meal the day of the test.

What Happens During the Test?

Once your blood sample is collected, it’s sent to a lab where it’s analyzed to measure glucose concentration. Results are typically ready within hours or the next day.

Reference range

Fasting: 70-100 mg/dLN/A

Specimen: whole-blood

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 (Serum)

Frequently asked questions

Why might my doctor order a glucose test if I don’t have symptoms?
Your doctor may recommend it to check for risk factors like obesity, a family history of diabetes, or to screen during pregnancy. It can also help monitor chronic conditions like heart disease or kidney problems.
What if my glucose level is higher or lower than expected?
Higher levels may signal diabetes or prediabetes, while lower levels could indicate hypoglycemia. Your doctor will discuss results with you and may suggest lifestyle changes, medications, or further testing.
Can I eat or drink anything before this test?
If fasting is required, avoid food and liquids (except water) for at least 8 hours before the test. If not fasting, eat a normal meal the day of the test. Always follow your healthcare provider’s specific instructions.
  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