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Glycated hemoglobin (HbA₁c) measured by high-performance liquid chromatography (HPLC)

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

This test measures the percentage of hemoglobin molecules that have sugar (glucose) attached, reflecting your average blood sugar levels over the past 2–3 months.

Quick summary

["Helps track long-term diabetes control and assess how well your blood sugar is managed over time."]

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

Key facts at a glance

LOINC
55237-2
Short code
HBA2 c.427T>C Bld Ql
Synonyms
HBA2 c.427T>C Bld Ql
Category
chemistry
Sample
whole-blood
Container
Lavender-top (EDTA)
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
Method
molgen
Specimen volume
3 mL
Stability
Room temperature: 4h, Refrigerated: 24h
Hemolysis max
0
Lipemia max
0
Icterus max
0
TAT
4–24 hours
Order
routine

Why This Test Matters

HbA₁c is a key indicator of how well your diabetes or prediabetes is managed. It provides a snapshot of your blood sugar control over a longer period than a single blood sugar test, helping doctors adjust treatments like medication or diet.

How It Works

Your blood sample is analyzed using high-performance liquid chromatography (HPLC), a precise method that separates and measures the different types of hemoglobin based on their sugar content.

Sample Collection

A small blood sample is drawn from your arm, similar to other blood tests. The test uses whole blood, not plasma or serum.

What to Expect Before the Test

No special preparation is needed, but inform your doctor if you’re taking certain medications (like blood thinners) or have a history of bleeding disorders.

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, HbA₁c is checked every 3–6 months for people with diabetes to track progress and adjust care plans as needed.
Can diet or exercise affect my HbA₁c results?
Yes, lifestyle changes like diet and exercise can improve HbA₁c levels. However, results reflect your average blood sugar over time, so consistent management is key.
What if my HbA₁c is higher than expected?
A higher HbA₁c may signal poor blood sugar control. Your doctor will review your treatment plan, including medications, diet, and activity levels, to help bring it down.
  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