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Hemoglobin A1c (HbA1c) with mass concentration measurement by immunoassay

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

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

Quick summary

["HbA1c helps track long-term diabetes control and is a key tool for managing blood sugar levels."]

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

Key facts at a glance

LOINC
4638-3
Short code
Hgb TL MFr RBC
Synonyms
Hgb TL MFr RBC
Category
hematology
Sample
whole-blood
Container
Lavender-top (EDTA)
Units
N/A
Ref low
4.2
Ref high
5.9
Critical range
7 N/A – 20 N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
CPT
85041
SNOMED
900000000000003001
Specimen volume
3 mL
Stability
Room temperature: 4h, Refrigerated: 24h
Hemolysis max
0
Lipemia max
0
Icterus max
0
TAT
4–24 hours
Order
routine

Why is HbA1c important?

HbA1c reflects your blood sugar levels over time because red blood cells live for about 3 months. It’s a more reliable indicator than checking glucose levels at random times, as it accounts for daily fluctuations.

How is HbA1c tested?

A small blood sample is taken, usually from your finger. The test measures the percentage of hemoglobin molecules that are attached to glucose, providing a snapshot of your average blood sugar over months.

What does an HbA1c result mean?

Results are typically reported as a percentage. While exact reference ranges vary by lab, higher percentages generally indicate poorer blood sugar control, while lower percentages suggest better management.

Common reasons for testing

HbA1c is often ordered for people with diabetes to monitor treatment effectiveness, for those at risk of diabetes, or as part of routine health screenings for prediabetes.

Reference range

Adult males: 4.2-5.9; Females: 3.8-5.1 x 10^12/LN/A

Specimen: whole-blood

No special preparation required. Stay well hydrated.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

◆Associated findings1

Short name

HbA1c

Frequently asked questions

What does an abnormal HbA1c result mean?
An abnormal result may signal uncontrolled diabetes, prediabetes, or other metabolic conditions. Your healthcare provider will discuss next steps, such as lifestyle changes or medication adjustments.
How often should I get an HbA1c test?
Typically, people with diabetes should get an HbA1c test every 3–6 months. Your doctor may recommend more frequent testing if your blood sugar is unstable or if you’re adjusting treatments.
Can HbA1c be affected by other health conditions?
Yes, conditions like anemia, kidney disease, or certain medications (e.g., some blood thinners) can influence HbA1c results. Always discuss your full medical history with your provider.
  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