Hemoglobin A1c (HbA1c) measured by high-performance liquid chromatography (HPLC)
This test measures the percentage of hemoglobin that is coated with sugar, reflecting your average blood sugar levels over the past 2–3 months. It helps doctors assess long-term blood sugar control, especially useful for managing diabetes.
["HbA1c provides a snapshot of your blood sugar management over time, aiding diabetes care."]
Key facts at a glance
- LOINC
- 58413-6
- Short code
- nRBC Bld Auto-Rto
- Synonyms
- nRBC Bld Auto-Rto
- Category
- chemistry
- Sample
- whole-blood
- Container
- Lavender-top (EDTA)
- Units
- N/A
- Ref low
- 4.2
- Ref high
- 5.9
- Critical range
- 2 N/A – 7 N/A
- Fasting
- false
- Population
- adult
- Sex
- all
- Age range
- 18–65 years
- Method
- automated-count
- CPT
- 85041
- SNOMED
- 900000000000003001
- 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 HbA1c Matters in Diabetes Management
HbA1c is a key tool for tracking how well your diabetes is controlled. Unlike daily blood sugar checks, it gives a broader picture over months, helping adjust treatments like diet, exercise, or medication. It’s often used alongside other tests to detect diabetes early or monitor progression.
How HbA1c Works
HbA1c forms when hemoglobin (the oxygen-carrying part of red blood cells) bonds with glucose (sugar) in your blood. As red blood cells live for about 3 months, this test reflects your average blood sugar levels during that time. The percentage is calculated by comparing the amount of HbA1c to total hemoglobin.
What HbA1c Results Mean
Results are typically reported as a percentage (e.g., 5.7%–6.4% is considered prediabetes; 6.5% or higher suggests diabetes). Lower percentages may indicate better blood sugar control, while higher percentages may signal poor management or complications like nerve damage or kidney issues.
Common Causes of Abnormal Results
HbA1c can be affected by factors like anemia (low red blood cells), certain medications (e.g., iron supplements), or pregnancy. If your results seem unusually high or low, discuss them with your doctor to rule out these influences.
Reference range
Adult males: 4.2-5.9; Females: 3.8-5.1 x 10^12/LN/A
No special preparation required. Stay well hydrated.
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?
What does an HbA1c of 6.0% mean for me?
Can HbA1c be affected by recent blood sugar spikes?
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 17, 2026. · Read our editorial policy