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Hemoglobin A1c (HbA1c) from whole blood

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

This test measures the average level of hemoglobin A1c in your blood over the past 2 to 3 months. Hemoglobin A1c reflects your blood sugar (glucose) levels during this time.

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
13306-6
Short code
HLA-DR Beta
Synonyms
HLA-DR Beta
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 monitor how well your blood sugar is controlled, especially if you have diabetes or prediabetes. It’s also used to diagnose diabetes in some cases, particularly if blood sugar levels fluctuate or if you have symptoms like excessive thirst or fatigue.

How is the test performed?

A small blood sample is taken from your arm, usually by a healthcare professional. The sample is then analyzed in a lab to measure the percentage of hemoglobin A1c in your blood.

What does the test result mean?

The result shows the percentage of hemoglobin molecules that are coated with sugar. While specific ranges can vary by lab, higher levels generally indicate poorer blood sugar control over time. Your provider will interpret the result in the context of your overall health and treatment plan.

What can affect this test?

Several factors may influence HbA1c results, including recent blood sugar levels, pregnancy, certain medical conditions (like kidney disease or anemia), and some medications. Smoking can also affect the test results.

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 this test?
The frequency depends on your health status. People with diabetes may get this test every 3 to 6 months, while those with prediabetes or no diabetes may need it less often or not at all unless advised otherwise.
What if my HbA1c is higher than expected?
A higher HbA1c suggests your blood sugar levels have been consistently above target over time. Your provider will work with you to identify causes (like diet, activity, or medication) and adjust your plan to improve control.
Can I eat or drink before this test?
You can eat and drink normally before the test, as it’s a blood sample collected without fasting. However, always follow your healthcare provider’s specific instructions for your appointment.
  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