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Hemoglobin A1c (HbA1c) from serum

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

This test measures the average level of hemoglobin A1c in your blood over the past 2–3 months, reflecting your blood sugar control during that time.

Quick summary

["HbA1c helps doctors track long-term diabetes management."]

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

Key facts at a glance

LOINC
22313-1
Short code
HAV IgG Ser-aCnc
Synonyms
HAV IgG Ser-aCnc
Category
chemistry
Sample
serum
Container
Red-top tube (SST)
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
CPT
82784
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 Is HbA1c?

HbA1c is a form of hemoglobin (the protein in red blood cells that carries oxygen) that has attached a sugar molecule (glucose). It reflects how your blood sugar levels have been over time. Unlike regular blood sugar tests, which only show current levels, HbA1c gives a snapshot of your average blood sugar for the previous 2–3 months.

Why Is This Test Done?

Doctors use HbA1c to diagnose diabetes, monitor treatment progress, and assess long-term blood sugar control in people with diabetes or prediabetes. It’s especially useful because it accounts for fluctuations in blood sugar that daily tests might miss.

How Is the Test Performed?

A small blood sample is taken from your arm, usually by a healthcare professional. The serum (liquid part of blood without clotting factors) is then analyzed in a lab to measure the percentage of hemoglobin A1c.

What Do Results Mean?

Results are typically reported as a percentage. Higher levels may indicate poorer blood sugar control, while lower levels may suggest better control. However, interpretation depends on your overall health, age, and other factors.

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 an HbA1c test?
Typically, people with diabetes are advised to get an HbA1c test every 3–6 months, depending on their treatment plan and blood sugar goals. Your doctor will determine the best schedule for you.
What does an abnormal HbA1c result mean?
An abnormal result means your blood sugar levels have been consistently higher or lower than recommended. This could indicate poor diabetes management, other health conditions, or the need for lifestyle or medication adjustments. Always discuss results with your healthcare provider.
Can HbA1c test results be affected by other factors?
Yes, factors like pregnancy, certain medications (e.g., iron supplements), or blood disorders can influence HbA1c levels. If you suspect these may apply to you, mention them to your doctor before or after your test.
  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