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Hemoglobin A1c (Glycated Hemoglobin) by Immunoassay

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

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

Quick summary

["HbA1c helps doctors 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
77464-6
Short code
Deprecated Hind+Mid ft XR Ski Jump
Synonyms
Deprecated Hind+Mid ft XR Ski Jump
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

Why This Test Matters for You

HbA1c is a key indicator of how well your body manages blood sugar, especially for people with diabetes or prediabetes. It provides a snapshot of your average glucose levels over time, helping prevent complications like nerve damage, kidney disease, or heart problems.

How the Test Works

Blood is drawn from a vein, typically in your arm. The test measures the proportion of hemoglobin molecules that have glucose attached, which is detected using an immunoassay method. Results are expressed as a percentage.

What to Expect Before or After the Test

No special preparation is needed, but you may avoid eating or drinking for 4–8 hours before testing if instructed. After the draw, you may feel slight discomfort, but rest assured it’s a quick and routine procedure.

Interpreting Your Results

Results are typically reported as a percentage (e.g., 5.7%, 6.4%, 7.5%). A result below 5.7% is generally considered normal, while 5.7%–6.4% suggests prediabetes, and 6.5% or higher indicates diabetes. Your doctor will discuss these numbers with you.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

Clinical Significance

Short name

HbA1c

Frequently asked questions

HbA1c is crucial for monitoring long-term blood sugar control in diabetes. It helps doctors adjust treatment plans, such as medication or diet, to keep glucose levels within a healthy range and reduce risks of diabetes-related complications.
HbA1c is not affected by short-term fluctuations in blood sugar, unlike daily glucose checks, making it a reliable measure of average glucose levels over months.
If I have diabetes, why do I need this test regularly?
Regular HbA1c testing helps your doctor track how well your diabetes is controlled and make necessary adjustments to your treatment plan to prevent complications.
Can fasting affect my HbA1c result?
No, HbA1c measures average blood sugar over time and is not influenced by fasting status. It reflects long-term glucose exposure, not just recent levels.
  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