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Glucose in Blood (Concentration)

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

This test measures the amount of glucose (sugar) in your blood. It helps assess how well your body is using sugar for energy and managing blood sugar levels.

Quick summary

["This test helps diagnose or monitor conditions related to blood sugar control."]

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

Key facts at a glance

LOINC
47995-6
Short code
Glucose BldCo-sCnc
Synonyms
Glucose BldCo-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 order glucose tests to check for diabetes, high or low blood sugar, or to monitor conditions like prediabetes, hypoglycemia, or metabolic disorders. It may also be done during pregnancy (gestational diabetes) or before certain surgeries.

How Is the Test Performed?

A small amount of blood is drawn from a vein, usually in your arm, using a needle. The blood sample is then sent to a lab for testing. The test can be done at a clinic, doctor’s office, or a lab.

What Do the Results Mean?

Results are typically reported in milligrams per deciliter (mg/dL) or millimoles per liter (mmol/L). While specific ranges vary by test type (e.g., fasting, random), abnormal results may indicate high or low blood sugar levels that need further evaluation.

Common Conditions Affecting Results

Factors like recent meals, physical activity, stress, illness, or certain medications can affect glucose levels. Chronic conditions like diabetes or kidney disease may also influence test results.

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

Frequently asked questions

What Is a Normal Glucose Level?
Normal glucose levels vary depending on whether the test was done fasting or after eating. For example, fasting glucose levels are usually between 70–99 mg/dL, while random glucose levels may be higher. Persistently high or low levels can signal diabetes, insulin resistance, or other metabolic issues.
How Often Should I Get This Test?
Your doctor will determine how often you need glucose tests based on your health status. People with diabetes may need tests every few months, while others may only need them once a year or less.
Can I Eat or Drink Before the Test?
Yes, but the instructions will depend on the type of test. For fasting glucose tests, you’ll typically avoid food and liquids (except water) for 8–12 hours before drawing blood. For random glucose tests, you can eat and drink normally.
  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