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Glucose, 3-Month Average (Hemoglobin A1c)

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

This test measures your average blood sugar levels over the past 3 months, linked to your long-term health. It helps doctors track diabetes management and prevent complications.

Quick summary

["A1c reflects your average glucose control over time, not just a single blood sugar reading."]

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

Key facts at a glance

LOINC
40262-8
Short code
Glucose 3M pre chal SerPl-mCnc
Synonyms
Glucose 3M pre chal 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

What Is A1c Used For?

A1c is primarily used to diagnose diabetes, assess how well your blood sugar is controlled over time, and monitor long-term health risks. It’s especially useful for people with type 1 or type 2 diabetes because it provides a clearer picture than daily blood sugar checks alone.

How Is A1c Different from Daily Blood Sugar Tests?

Unlike daily blood sugar tests (like fingerstick glucose checks), A1c gives a broader view of your average glucose levels over months. It accounts for fluctuations you might not notice daily, helping doctors adjust treatment plans more effectively.

How Is This Test Performed?

A1c is measured from a small blood sample taken from your arm. The test involves analyzing your red blood cells to determine the percentage of hemoglobin that is coated with glucose. No special preparation is needed, but fasting is not required.

What Does an A1c Result Mean?

Your A1c result is expressed as a percentage. For example, an A1c of 6.5% means your blood sugar was typically around 150 mg/dL higher than normal over the past 3 months. Results are interpreted by your healthcare provider based on your medical history and goals.

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.

Clinical Significance: Why Is A1c Important?

Short name

A1c (3-Month Glucose Average)

Frequently asked questions

Why do I need an A1c test?
If you have diabetes, an A1c test helps your doctor check if your treatment is working to keep your blood sugar within a healthy range. It also helps detect diabetes early if you have symptoms like frequent urination, excessive thirst, or unexplained weight loss. For people without diabetes, A1c can help identify prediabetes or high-risk conditions.
How often should I get an A1c test?
For people with diabetes, A1c tests are usually recommended every 3 to 6 months. If you have prediabetes, your doctor may suggest testing once a year. If you don’t have diabetes, routine A1c testing isn’t standard unless you have risk factors like obesity, a family history of diabetes, or high blood pressure.
Can A1c results change over time?
Yes, A1c results can change based on your diet, exercise, medications, and overall health. If you notice sudden changes in your A1c, discuss them with your doctor. Small fluctuations may occur, but significant drops or rises could signal underlying health issues or the need for treatment adjustments.
  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