Skip to content

Hemoglobin A1c (HbA1c) with High-Performance Liquid Chromatography (HPLC) measurement

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

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

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
18277-4
Short code
Hgb F Gast Ql Apt-Downey
Synonyms
Hgb F Gast Ql Apt-Downey
Category
hematology
Sample
serum
Container
Red-top tube (SST)
Units
N/A
Ref low
10
Ref high
40
Critical range
7 N/A – 20 N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
Method
apt-downey
CPT
84484
SNOMED
302774002
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

What Does HbA1c Measure?

HbA1c reflects your average blood sugar levels over time by showing how much of your hemoglobin has sugar molecules attached. It’s a key indicator of how well your body manages glucose (sugar) in your blood, especially important for people with diabetes or prediabetes.

Why Is HbA1c Important?

This test is crucial for monitoring long-term blood sugar control because it provides a snapshot of your average glucose levels over months, unlike daily blood sugar checks. It helps doctors assess whether your treatment plan is effective and adjust it as needed.

How Is HbA1c Tested?

Your blood sample is analyzed using high-performance liquid chromatography (HPLC), a precise method that separates and measures different types of hemoglobin, including the glycated form (HbA1c). This method ensures accurate results.

What Does a High or Low HbA1c Mean?

A higher HbA1c percentage typically indicates poorer blood sugar control, while a lower percentage may suggest better control—but individual results depend on your health status and treatment. Always discuss results with your healthcare provider.

Reference range

Adult: 10-40 U/LN/A

Specimen: serum

No special preparation required. Avoid fatty meals before the test if possible.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

◆Associated findings1

Short name

HbA1c

Frequently asked questions

What causes HbA1c levels to change?
HbA1c levels can be influenced by diet, physical activity, medications (like insulin or diabetes drugs), chronic illnesses (e.g., kidney disease), and recent blood sugar fluctuations. Stress, infections, or recent blood transfusions may also temporarily affect results.
How often should I get an HbA1c test?
Your doctor will recommend how often to test based on your diabetes management plan. Typically, people with diabetes may get HbA1c tests every 3–6 months, while others may need less frequent checks.
Can lifestyle changes affect HbA1c results?
Yes! Regular exercise, a balanced diet, and managing stress can improve HbA1c levels over time. Even small changes, like reducing sugar intake or quitting smoking, may lead to better long-term blood sugar control.
  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