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Hemoglobin A1c (HbA1c) measured by high-performance liquid chromatography (HPLC)

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

This test measures your average blood sugar levels over the past 2–3 months by examining the percentage of hemoglobin (red blood cell protein) that is coated with sugar.

Quick summary

["HbA1c helps doctors track long-term diabetes control."]

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

Key facts at a glance

LOINC
18577-7
Short code
J Pnt ST Amp+80ms L-V4
Synonyms
J Pnt ST Amp+80ms L-V4
Category
chemistry
Sample
serum
Container
Red-top tube (SST)
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
Method
ekg
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 HbA1c important?

Unlike daily blood sugar checks, HbA1c gives a broader picture of how well your blood sugar has been managed over time. It’s a key tool for diagnosing diabetes and assessing treatment effectiveness.

How is HbA1c tested?

A small blood sample is taken from your arm and analyzed using HPLC, a precise method that separates hemoglobin types based on their sugar content.

What does an HbA1c result mean?

Results are typically reported as a percentage (e.g., 5.7%–6.4% may indicate prediabetes, while 6.5% or higher suggests diabetes). Your doctor will interpret results in the context of your overall health.

Common reasons for testing

HbA1c is often ordered to diagnose diabetes, monitor pre-existing conditions, or check for undiagnosed glucose issues. It’s also useful for pregnant women, people with kidney disease, or those with frequent high blood sugar symptoms.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

Clinical significance: HbA1c is a gold-standard marker for chronic blood sugar management. It reflects metabolic control over months, helping prevent complications like nerve damage, kidney disease, or heart disease. Lower-than-target levels may signal over-treatment, while persistently high levels may require lifestyle or medication adjustments.

Short name

HbA1c

Frequently asked questions

What does an HbA1c test involve?
You’ll have a small needle inserted into your arm to draw a tiny blood sample. The process is quick and painless, similar to a routine blood draw. No special preparation is needed, but fasting isn’t required.
How often should I get an HbA1c test?
Your doctor will determine frequency based on your health status. Typically, people with diabetes test every 2–4 months, while others may test annually or as needed to track trends.
Can HbA1c results change over time?
Yes, HbA1c levels can fluctuate due to diet, exercise, illness, or medications. If your results are consistently high or low, discuss changes with your healthcare provider to adjust your care plan.
  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