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Hemoglobin A1c (HbA1c) Test

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

This test measures the average blood sugar levels over the past 2 to 3 months by examining your red blood cells.

Quick summary

["Helps track long-term blood sugar control for diabetes management."]

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

Key facts at a glance

LOINC
52041-1
Short code
Blood glucose monitor attachment
Synonyms
Blood glucose monitor attachment
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

What Does This Test Measure?

HbA1c reflects the percentage of hemoglobin molecules that are coated with sugar (glycated). It’s a marker of how well your blood sugar has been controlled over time, as red blood cells live for about 3 months. This test is crucial for diagnosing diabetes and monitoring treatment effectiveness.

Why Is This Test Important?

Regular HbA1c testing helps prevent complications like nerve damage, kidney disease, and vision problems by ensuring consistent blood sugar management. It’s often used alongside other tests to assess overall health in people with diabetes.

How Is the Test Performed?

A small blood sample is taken from your arm, usually via a simple needle. The sample is then analyzed in a lab to measure the percentage of glycated hemoglobin. Results are reported as a percentage (e.g., 6.5% or 7.2%).

What Are Common Results?

Results are typically reported as a percentage, but exact values can vary by lab. A result below 5.7% is generally considered normal, while 5.7% to 6.4% indicates prediabetes. A result of 6.5% or higher suggests diabetes.

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

HbA1c

Frequently asked questions

How Often Should I Get This Test?
If you have diabetes, your healthcare provider may recommend testing every 3 to 6 months to monitor progress and adjust treatments like medication or diet. For prediabetes, testing may be less frequent but still important for early intervention.
What If My HbA1c Is High?
A high HbA1c suggests poor blood sugar control. Your doctor may recommend lifestyle changes (like diet and exercise), prescription medications, or other treatments to lower your levels. Follow-up tests will help track improvements.
Does HbA1c Change with Illness or Stress?
Yes, illness, stress, or infections can temporarily raise HbA1c levels. If you’re sick or experiencing significant stress, your doctor may wait to retest until your blood sugar stabilizes to avoid misleading results.
  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