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Hemoglobin A1c (HbA1c) by High-Performance Liquid Chromatography (HPLC) in Serum

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

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

Quick summary

["HbA1c helps doctors assess long-term blood sugar control, important for managing diabetes."]

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

Key facts at a glance

LOINC
21259-7
Short code
E histolyt Ab Titr Ser HA
Synonyms
E histolyt Ab Titr Ser HA
Category
chemistry
Sample
serum
Container
Red-top tube (SST)
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
Method
ha
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 Your Health

HbA1c is a key indicator of how well your blood sugar has been controlled over time. Unlike daily blood sugar checks, it provides a broader picture of your average glucose levels, helping prevent long-term complications like nerve damage, kidney disease, or heart problems.

How the Test Works

Your blood sample is analyzed using high-performance liquid chromatography (HPLC), a precise method that separates and measures different types of hemoglobin, including those bound to sugar. This process helps determine the percentage of hemoglobin A1c in your blood.

What to Expect Before the Test

No special preparation is needed for this test. You may have a fingerstick blood draw, similar to a regular blood sugar check, or your blood may be collected from a vein. If you’re on dialysis, your blood is taken from your access site.

Common Causes of Abnormal Results

Elevated HbA1c levels may suggest poor blood sugar control, often linked to diabetes or prediabetes. Lower-than-normal levels can sometimes indicate very low blood sugar or certain blood disorders, though this is rare. Always discuss results with your healthcare provider.

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 HbA1c result means your blood sugar levels have been consistently higher or lower than what’s considered healthy over time. High levels may indicate diabetes or poor management of diabetes, while very low levels could signal other conditions like severe hypoglycemia or rare blood disorders. Your doctor will discuss these findings with you and help determine next steps.
How often should I get this test?
The frequency depends on your health status. People with diabetes are often tested every 2–4 months to track progress. Your doctor may recommend more or fewer tests based on your treatment plan, blood sugar trends, and overall health.
Can diet or exercise affect HbA1c results?
Yes, diet and exercise can influence HbA1c levels. Regular physical activity and a balanced diet can help lower blood sugar over time, improving your HbA1c. However, this test reflects long-term trends, so immediate changes in diet or activity won’t show results overnight.
  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