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

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

This test measures the average blood sugar levels over the past 2–3 months by checking the percentage of hemoglobin (the oxygen-carrying part of red blood cells) that is coated with sugar.

Quick summary

["Helps doctors assess 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
21343-9
Short code
HLADRDQ
Synonyms
—
Category
chemistry
Sample
serum
Container
Red-top tube (SST)
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
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

Unlike daily blood sugar checks, HbA1c provides a snapshot of how well your blood sugar has been managed over time. It’s a key tool for diagnosing diabetes and monitoring treatment effectiveness, especially in people who don’t test their blood sugar regularly.

How the Test Works

Blood is drawn, and the hemoglobin is separated from other blood components. High-performance liquid chromatography (HPLC) then sorts the hemoglobin types based on their sugar coating, allowing the lab to calculate the percentage of hemoglobin with sugar (HbA1c).

What to Expect Before the Test

No special preparation is needed, but you may fast for 8–12 hours before testing if instructed by your healthcare provider. Wear comfortable clothing for the blood draw, and let your doctor know about any medications or conditions that might affect results.

Common Causes of Abnormal Results

Elevated HbA1c levels often indicate poor blood sugar control and may signal diabetes or prediabetes. Lower-than-normal levels can sometimes occur in people with very low blood sugar over time or certain blood disorders. Always discuss results with your doctor.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

Clinical Significance

Short name

HbA1c

Frequently asked questions

How often should I get this test?
Typically, people with diabetes check their HbA1c every 3–6 months. Your doctor may recommend more frequent testing if your blood sugar is hard to control or if you have other health conditions that affect blood sugar.
Can diet or exercise affect my HbA1c results?
Yes, lifestyle changes like diet and exercise can improve blood sugar control, which may lower your HbA1c over time. However, HbA1c reflects long-term trends, so it may take weeks or months to see changes in your test results.
What if my HbA1c is higher than expected?
If your HbA1c is higher than your doctor’s target range, it may mean you need adjustments to your diabetes management plan, such as medication changes, improved diet, or increased physical activity. Follow-up visits will help determine the best next steps.
  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