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Hemoglobin A1c (HbA1c) measured by high-performance liquid chromatography (HPLC)

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

This test measures the average level of blood sugar (glucose) over the past 2–3 months by examining your red blood cells.

Quick summary

["HbA1c helps track long-term blood sugar control, useful for managing diabetes."]

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

Key facts at a glance

LOINC
93351-5
Short code
HLA-DR Ag EntNum Mono FC
Synonyms
HLA-DR Ag EntNum Mono FC
Category
chemistry
Sample
serum
Container
Red-top tube (SST)
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
Method
flow-cytometry
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

Why is HbA1c important?

Unlike daily blood sugar checks, HbA1c gives a broader picture of how well your body manages glucose over time. It’s a key tool for doctors to adjust diabetes treatments and prevent complications like nerve damage or heart disease.

How is HbA1c tested?

A small blood sample is taken from your arm and analyzed using high-performance liquid chromatography (HPLC), a precise method that separates hemoglobin types to measure the percentage of hemoglobin bound to glucose.

What does an HbA1c result mean?

Results are typically reported as a percentage (e.g., 5.7%–6.4% is considered prediabetes; 6.5% or higher suggests diabetes). However, individual reference ranges may vary by lab, so discuss your result with your healthcare provider.

How often should HbA1c be checked?

For people with diabetes, HbA1c is usually checked every 3–6 months to monitor progress and adjust treatment plans. Your doctor may recommend more frequent checks if your blood sugar is unstable.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

◆Associated findings1

Short name

HbA1c

Frequently asked questions

What does an HbA1c test measure?
It measures the percentage of hemoglobin molecules that have glucose attached, indicating your average blood sugar levels over the past 2–3 months.
How does HbA1c differ from a fasting blood sugar test?
HbA1c provides a longer-term snapshot (2–3 months) of blood sugar control, while a fasting blood sugar test checks immediate glucose levels after an overnight fast.
Can lifestyle changes affect HbA1c results?
Yes, diet, exercise, and diabetes medications can influence HbA1c. Consistent lifestyle improvements may lower your HbA1c over time, but results depend on adherence to treatment plans and overall health.
  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