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Hemoglobin A1c (HbA1c) from whole blood

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

This test measures the average blood sugar levels over the past 2–3 months by examining your red blood cells. It helps doctors assess long-term diabetes control.

Quick summary

["HbA1c reflects your blood sugar trends over time, aiding diabetes management."]

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

Key facts at a glance

LOINC
50604-8
Short code
HPA Pnl Bld
Synonyms
HPA Pnl Bld
Category
chemistry
Sample
whole-blood
Container
Lavender-top (EDTA)
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
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

What HbA1c Tests Measure

HbA1c tests your body’s ability to manage glucose by tracking how much sugar is attached to hemoglobin—a protein in red blood cells. This attachment reflects your average blood sugar levels over months, not just recent spikes or drops.

Why It’s Done

Doctors order HbA1c tests to diagnose diabetes, monitor treatment progress, or check for undiagnosed high blood sugar. It’s especially useful for people with type 1 or type 2 diabetes, prediabetes, or those at risk for complications.

How It Works

Blood is drawn, and the test measures the percentage of hemoglobin molecules bonded to glucose. The result is expressed as a percentage (e.g., 5.7%–6.4% may indicate prediabetes).

What the Results Mean

Results below 5.7% suggest good control, while 5.7%–6.4% may indicate prediabetes. Levels at or above 6.5% typically confirm diabetes. Values above 9% may signal poor control or complications like kidney disease.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

HbA1c is critical for diabetes management because it provides a long-term snapshot of blood sugar trends. Low values may indicate overly aggressive treatment, while high values signal uncontrolled diabetes risking nerve, heart, or kidney damage. Regular monitoring helps adjust lifestyle or medication.

Short name

HbA1c

Frequently asked questions

How often should I get an HbA1c test?
Typically every 3–6 months if you have diabetes, or annually if you have prediabetes. Your doctor may adjust frequency based on your health goals and treatment plan.
What affects my HbA1c test results?
Factors like recent blood sugar swings, pregnancy, certain medications (e.g., birth control), or blood disorders (e.g., anemia) can temporarily alter results. Always discuss these with your provider.
Can I eat or drink before an HbA1c test?
No fasting is required. However, avoid sugary drinks or snacks before your blood draw to ensure accurate results, as they may temporarily raise your blood sugar.
  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