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Hemoglobin A1c (HbA1c) - Glycosylated Hemoglobin

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

This test measures the percentage of hemoglobin in your blood that is attached to sugar (glucose). It reflects your average blood sugar levels over the past 2–3 months.

Quick summary

["HbA1c helps doctors 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
77472-9
Short code
Deprecated Hind+Mid ft-L XR 1V
Synonyms
Deprecated Hind+Mid ft-L XR 1V
Category
chemistry
Sample
serum
Container
Red-top tube (SST)
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
Method
xr
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 a form of hemoglobin (the protein in red blood cells that carries oxygen) that has been linked to glucose molecules. Over time, high blood sugar levels cause this attachment, creating HbA1c. This test provides a snapshot of how well your blood sugar has been controlled during this period.

Why Is HbA1c Important?

This test is crucial for diagnosing diabetes and monitoring treatment effectiveness. It’s less affected by short-term fluctuations in blood sugar compared to checking blood glucose levels immediately.

How Is HbA1c Tested?

The test involves a simple blood draw from a vein in your arm. The blood sample is analyzed to determine the percentage of hemoglobin that is glycosylated (attached to sugar).

How Often Should You Get HbA1c Tested?

For people with diabetes, HbA1c tests are typically recommended every 3–6 months to monitor progress and adjust treatment plans. Healthy individuals may get tested less frequently, depending on risk factors.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

◆Associated findings1

Short name

HbA1c

Frequently asked questions

How does HbA1c relate to diabetes diagnosis?
An HbA1c level of 6.5% or higher on two separate tests is used to diagnose diabetes. Levels between 5.7% and 6.4% suggest prediabetes, indicating increased risk of developing diabetes.
Can HbA1c help predict future health risks?
Yes, consistently high HbA1c levels are linked to long-term complications like nerve damage, kidney disease, and heart disease. Regular monitoring helps prevent these risks.
What does a low HbA1c level mean?
A low HbA1c level (typically below 5.7%) suggests good blood sugar control and may indicate effective diabetes management or no diabetes. However, it’s not a substitute for regular blood glucose checks.
  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