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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 blood sugar levels over the past 2 to 3 months by examining the percentage of hemoglobin that is coated with sugar.

Quick summary

["HbA1c reflects your long-term blood sugar control."]

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

Key facts at a glance

LOINC
56564-8
Short code
GH 8h p chal SerPl-mCnc
Synonyms
GH 8h p chal SerPl-mCnc
Category
chemistry
Sample
serum
Container
Red-top tube (SST)
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
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 this test done?

Your healthcare provider may order an HbA1c test to check how well your diabetes or prediabetes is managed. It helps assess your risk for complications like nerve damage, kidney disease, or heart disease over time.

What does the test involve?

A small blood sample is taken from your arm, usually in a clinic or lab. The blood is processed to measure the percentage of hemoglobin that has sugar attached, which indicates your average blood sugar levels.

What do the results mean?

Results are typically reported as a percentage. While specific ranges can vary, higher percentages suggest poorer blood sugar control, while lower percentages may indicate better control. Your results will be interpreted by your healthcare provider in the context of your overall health.

What can affect this test?

Several factors can influence HbA1c results, including recent blood sugar levels, pregnancy, certain medications (like iron supplements), and blood disorders. Your healthcare provider will consider these factors when reviewing your results.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

Clinical significance: HbA1c is a critical marker for diabetes management. It provides a snapshot of blood sugar control over time, helping to prevent long-term complications and guide treatment adjustments. Regular monitoring is essential for people with diabetes or those at high risk.

Short name

HbA1c

Frequently asked questions

How often should I get this test?
Your healthcare provider will determine the frequency based on your health status. Typically, people with diabetes may get tested every 2 to 4 months, while others may need it less often.
What if my HbA1c is higher than expected?
A higher HbA1c may indicate poor blood sugar control. Your provider will discuss strategies to improve it, such as adjusting diet, exercise, or medication, and may recommend additional tests or follow-ups.
Does diet or exercise affect HbA1c results?
Yes, lifestyle changes like diet and exercise can significantly impact HbA1c levels. Improving these habits can help lower your HbA1c and better manage your blood sugar over time.
  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