Hemoglobin A1c (HbA1c) by Immunoassay (Serum)
This test measures the percentage of hemoglobin in your blood that is coated with sugar, reflecting your average blood sugar levels over the past 2–3 months.
["Helps track long-term blood sugar control for diabetes management."]
Key facts at a glance
- LOINC
- 5190-4
- Short code
- HBV e Ab Ser RIA-aCnc
- Synonyms
- HBV e Ab Ser RIA-aCnc
- Category
- chemistry
- Sample
- serum
- Container
- Red-top tube (SST)
- Units
- N/A
- Fasting
- false
- Population
- adult
- Sex
- all
- Age range
- 18–65 years
- Method
- ria
- 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 Does This Test Measure?
HbA1c measures the proportion of hemoglobin molecules linked to glucose (sugar) over time. Hemoglobin is the protein in red blood cells that carries oxygen, and this test reflects how much sugar has attached to it during your blood’s lifespan (about 3 months).
Why Is This Test Important?
Unlike checking blood sugar levels at a single moment, HbA1c gives a broader picture of your blood sugar trends. It’s a key tool for doctors to assess whether your diabetes treatment is working effectively and to adjust care plans as needed.
How Is the Test Performed?
A small blood sample is drawn from your arm, typically during a routine visit to your healthcare provider’s office. The blood is processed to measure the percentage of hemoglobin A1c in your serum (liquid part of blood).
What Are Common Results?
Results are reported as a percentage (e.g., 5.7%, 6.4%, 7.5%). While specific ranges vary by lab, higher percentages generally indicate poorer blood sugar control over time. Your doctor will interpret results in the context of your overall health and treatment plan.
Clinical interpretation
How abnormal results are interpreted and what conditions they suggest.
◆Associated findings1
Short name
HbA1c
Frequently asked questions
HbA1c is a critical marker for diabetes management. Levels above 6.5% are often considered diagnostic for diabetes, while levels between 5.7% and 6.4% may indicate prediabetes. Regular monitoring helps prevent complications like nerve damage, kidney disease, and heart disease by allowing timely adjustments to diet, exercise, or medication.
For people with diabetes, HbA1c testing is typically recommended every 3–6 months to monitor progress and make necessary adjustments to your treatment plan. Your healthcare provider will determine the frequency based on your specific needs and how well your blood sugar is controlled.
An abnormal HbA1c result may suggest that your blood sugar levels have been consistently too high or too low over time. This could indicate poor diabetes management, underlying health conditions, or the need for changes in medication, diet, or lifestyle. Your doctor will discuss these findings with you and help you develop a plan to address them.
Sources
- 1
- 2Lab Tests OnlineSource
- 3
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.
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