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Hemoglobin A1c (HbA1c) in Serum/Plasma

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

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

Quick summary

HbA1c reflects your blood sugar management over time, aiding diabetes care.

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

Key facts at a glance

LOINC
64362-7
Short code
DIALYSISPATIENTSWHOHAVEPENDINGENROLLMENTINMEDICAREATENDOFREPORTINGPE
Synonyms
—
Category
chemistry
Sample
serum
Container
Red-top tube (SST)
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
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 HbA1c important?

HbA1c is a key marker for diabetes management because it provides a snapshot of how well your blood sugar has been controlled over months. Unlike daily blood glucose checks, it gives a broader picture of your health status related to diabetes.

How is HbA1c tested?

This test involves a simple blood draw from a vein in your arm. The blood sample is processed to measure the percentage of hemoglobin that is coated with sugar (HbA1c). Results are typically reported as a percentage.

What does an HbA1c result mean?

Your HbA1c result helps your healthcare provider determine if your diabetes is well-controlled. Lower percentages indicate better blood sugar management, while higher percentages suggest poorer control and may require adjustments to your treatment plan.

What can affect HbA1c results?

Several factors can influence HbA1c levels, including recent blood sugar fluctuations, pregnancy, certain medications, and conditions like anemia or kidney disease. It’s important to discuss these with your doctor to interpret results accurately.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

Clinical Significance: HbA1c is a critical tool for diagnosing diabetes, monitoring its progression, and evaluating treatment effectiveness. It reduces reliance on daily blood glucose measurements and helps prevent long-term complications like nerve damage, kidney disease, or heart problems by identifying trends in blood sugar control.

Short name

HbA1c

Frequently asked questions

What does an HbA1c test tell me about my diabetes?
An HbA1c test tells you the average blood sugar level over the past 2–3 months. It helps your doctor see if your diabetes is well-managed and whether your treatment plan is working effectively.
How often should I get an HbA1c test?
Your doctor will determine how often you need an HbA1c test based on your diabetes management plan. Typically, people with diabetes are tested every 3 months, but this can vary depending on your health and treatment needs.
Can HbA1c results change if I’ve recently had a blood sugar spike or drop?
Yes, recent blood sugar spikes or drops can temporarily affect HbA1c levels. If you’ve had significant changes in your blood sugar recently, your doctor may ask for additional testing or clarification.
  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