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Hemoglobin A1c (HbA1c) with Immunoassay Method

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

This test measures the percentage of hemoglobin that is coated with glycated sugar, reflecting your average blood sugar levels over the past 2–3 months.

Quick summary

["HbA1c helps 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
14231-5
Short code
H2a-H2b DNA IgG Ser-aCnc
Synonyms
H2a-H2b DNA IgG Ser-aCnc
Category
chemistry
Sample
serum
Container
Red-top tube (SST)
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
CPT
82784
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

How HbA1c Works

HbA1c is formed when glucose (sugar) binds to hemoglobin, the protein in red blood cells that carries oxygen. This binding is permanent, so the test reflects your blood sugar levels from the time your red blood cells were made (about 2–3 months prior).

Why It Matters for Your Health

Regular HbA1c testing is crucial for people with diabetes to monitor how well their blood sugar is controlled. It also helps doctors adjust treatments and prevent complications like nerve damage, kidney disease, or heart problems.

What to Expect During the Test

A small blood sample is taken from your arm, usually by a phlebotomist. The blood is processed to measure the percentage of HbA1c in your red blood cells. No special preparation is needed, but fasting is not required.

Factors That Can Affect Results

Several factors may influence HbA1c levels, including recent blood sugar fluctuations, anemia, certain medications (like blood thinners), or conditions like kidney disease or pregnancy. Your doctor will consider these when interpreting your results.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

Clinical Significance

Short name

HbA1c

Frequently asked questions

An HbA1c level above 6.5% on two separate tests typically indicates diabetes. Levels between 5.7% and 6.4% suggest prediabetes, while levels below 5.7% are generally considered normal. This test is a key tool for diagnosing diabetes and assessing long-term blood sugar control.
This test is performed using an immunoassay method, which detects the glycated hemoglobin in your blood. It’s a reliable way to get an average picture of your blood sugar over time, unlike a single blood sugar test, which only shows your level at that moment.
How often should I get an HbA1c test?
For people with diabetes, HbA1c testing is usually recommended every 3–6 months. Your doctor may adjust this frequency based on your blood sugar control and overall health. If you don’t have diabetes but have risk factors (like obesity or a family history), your doctor may recommend testing once a year.
Can HbA1c levels change quickly?
Yes, HbA1c levels can change gradually over time due to lifestyle changes, diet, or treatment adjustments. However, it typically takes several weeks to months for significant shifts in your HbA1c level to reflect changes in your average blood sugar.
  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