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

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

This test measures the percentage of hemoglobin that is coated with sugar, reflecting your average blood sugar levels over the past 2–3 months.

Quick summary

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

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

Key facts at a glance

LOINC
30719-9
Short code
XR tomo TMJ
Synonyms
XR tomo TMJ
Category
chemistry
Sample
serum
Container
Red-top tube (SST)
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
Method
xr-tomography
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 HbA1c Tests Measure

HbA1c is a form of hemoglobin (the protein in red blood cells that carries oxygen) that has been linked to glucose (sugar) over time. It’s a stable marker that reflects your average blood sugar levels during the production of red blood cells, which lasts about 3 months. This test is particularly useful for diagnosing diabetes and monitoring treatment effectiveness.

Why This Test Matters

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 preventing complications like nerve damage, kidney disease, and vision problems linked to high blood sugar.

How the Test Works

Blood is drawn from a vein, usually in your arm. The sample is processed to separate hemoglobin from other blood components. HPLC separates hemoglobin variants based on their sugar content, allowing precise measurement of HbA1c.

What to Expect Before the Test

No special preparation is needed, but inform your doctor about any medications (especially blood sugar drugs) or recent illnesses that might affect results. Fasting is not required.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

Clinical Significance

Short name

HbA1c

Frequently asked questions

What does an abnormal HbA1c result mean?
An HbA1c result above the typical range (often 4–6% for healthy individuals, higher in diabetes) suggests poor blood sugar control. A result below the range may indicate consistently low blood sugar, though this is less common and requires further evaluation.
Can HbA1c be affected by other conditions?
Yes, conditions like anemia, kidney disease, or certain medications (e.g., some blood thinners) can influence HbA1c levels. Your doctor may order additional tests if results seem unusual.
How often should I get this test?
For people without diabetes, a single HbA1c test may be done occasionally to screen for prediabetes or diabetes. Those with diabetes typically get it every 3–6 months to track progress.
  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