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Hemoglobin A1c (HbA1c) – Glycated Hemoglobin

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

This test measures the percentage of hemoglobin in your blood that has been linked to sugar (glucose), reflecting your average blood sugar levels over the past 2–3 months.

Quick summary

["HbA1c helps doctors track diabetes management and long-term blood sugar control."]

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

Key facts at a glance

LOINC
28168-3
Short code
TAKETIMEFORIMPORTANTTHINGS
Synonyms
—
Category
chemistry
Sample
serum
Container
Red-top tube (SST)
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
Method
reported-living-hiv
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 Does HbA1c Measure?

HbA1c is formed when hemoglobin molecules bind to excess glucose in your blood. Over time, this creates a stable, sugar-coated version of hemoglobin. The test quantifies this percentage to estimate how well your blood sugar has been controlled during this period.

Why Is HbA1c Important?

Unlike daily blood sugar checks, HbA1c provides a broader picture of your blood sugar trends, helping identify patterns like poor control or recent fluctuations that might not show up in quick spot tests.

How Is HbA1c Tested?

This test uses a simple blood draw from your arm. The sample is analyzed using an immunoassay method to detect glycated hemoglobin levels, which are then reported as a percentage.

What Are Typical Results?

Results are expressed as a percentage (e.g., 5.7%, 6.4%, 7.5%). While reference ranges vary by lab, higher percentages generally indicate higher average blood sugar levels, often linked to diabetes or prediabetes.

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 an HbA1c test?
If you have diabetes, your doctor may recommend testing every 3–6 months to track progress with medications or lifestyle changes. For prediabetes, some may test annually or more frequently.
Can HbA1c be affected by other health conditions?
Yes, conditions like anemia (low red blood cells), kidney disease, or certain medications (e.g., blood thinners) can influence HbA1c results. Always discuss your test with your provider if you have concerns.
What if my HbA1c is higher than expected?
A higher HbA1c may signal poor blood sugar control. Your doctor might adjust treatments (like diet, exercise, or insulin) or check for underlying issues like insulin resistance or other health conditions.
  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