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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 track long-term diabetes control."]

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

Key facts at a glance

LOINC
33543-0
Short code
GA from HC.Hansmann86
Synonyms
GA from HC.Hansmann86
Category
chemistry
Sample
serum
Container
Red-top tube (SST)
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
Method
us-estimated-from-hc-hansmann
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 this test done?

Your doctor may order an HbA1c test to assess how well your blood sugar is managed over time, especially if you have diabetes or prediabetes. It’s a key tool for monitoring treatment effectiveness and detecting complications early.

How is the sample collected?

A small blood sample is taken from your arm, usually by a healthcare professional using a needle. The blood is processed to separate the hemoglobin component for analysis.

What does the result mean?

Results are reported as a percentage, indicating the proportion of hemoglobin molecules linked to glucose. Higher percentages suggest poorer blood sugar control, while lower percentages may indicate better management. Exact values help guide treatment adjustments.

Common reasons for testing

HbA1c is commonly used for routine diabetes screening, diagnosis, and ongoing management. It’s also checked during pregnancy (in gestational diabetes) and in people with risk factors like obesity, family history, or high blood pressure.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

◆Associated findings1

Short name

HbA1c

Frequently asked questions

How often should I get this test?
Typically, people with diabetes check their HbA1c every 3–6 months to monitor progress. Your doctor will determine the frequency based on your specific needs, treatment plan, and overall health.
What can affect my HbA1c results?
Several factors can influence HbA1c, including recent blood sugar fluctuations, iron deficiency, kidney disease, or certain medications. If you suspect these may affect your results, discuss them with your healthcare provider.
Is there anything I should do before the test?
No special preparation is needed, but avoid smoking or drinking coffee immediately before the blood draw, as these can temporarily alter blood sugar levels and affect results.
  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