Hemoglobin A1c (HbA1c) measured by high-performance liquid chromatography (HPLC)
This test measures the average level of blood sugar (glucose) over the past 2–3 months by examining the percentage of hemoglobin that is coated with glucose.
["Helps track long-term blood sugar control for diabetes management."]
Key facts at a glance
- LOINC
- 4608-6
- Short code
- Hgb M-Iwate Bld Ql
- Synonyms
- Hgb M-Iwate Bld Ql
- Category
- hematology
- Sample
- whole-blood
- Container
- Lavender-top (EDTA)
- Units
- N/A
- Ref low
- 12
- Ref high
- 17.5
- Critical range
- 7 N/A – 20 N/A
- Fasting
- false
- Population
- adult
- Sex
- all
- Age range
- 18–65 years
- CPT
- 85018
- SNOMED
- 900000000000003004
- 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 is HbA1c important?
HbA1c reflects your blood sugar levels over time because hemoglobin (the protein in red blood cells) stays in your bloodstream for about 3 months. This test is a key tool for doctors to assess how well your diabetes is managed and adjust treatment plans accordingly.
How is HbA1c tested?
Your blood sample is processed using high-performance liquid chromatography (HPLC), a method that separates and measures the different types of hemoglobin, including the one bound to glucose. This provides an accurate measure of your average blood sugar levels.
What does an HbA1c result mean?
An HbA1c result is expressed as a percentage. It indicates the proportion of your hemoglobin molecules that have glucose attached. For example, an HbA1c of 6.5% means that 6.5% of your hemoglobin is coated with glucose. This percentage helps doctors determine if your blood sugar levels are within a healthy or target range for diabetes.
What are typical HbA1c reference ranges?
There is no single reference range for everyone, as it varies based on health status and treatment goals. Generally, a result below 5.7% is considered normal, 5.7%–6.4% is prediabetes, and 6.5% or higher suggests diabetes. Your doctor will interpret the result in relation to your specific health needs.
Reference range
Adult males: 13.5-17.5 g/dL; Females: 12.0-16.0 g/dLN/A
No special preparation usually required. Stay well hydrated. Inform your healthcare provider of all medications and supplements you are taking.
Clinical interpretation
How abnormal results are interpreted and what conditions they suggest.
Clinical significance: HbA1c is a critical marker for diagnosing diabetes and monitoring long-term blood sugar control. It provides a more reliable picture than daily blood sugar checks alone, as it accounts for fluctuations and averages your glucose levels over time. Regular monitoring helps prevent complications like nerve damage, kidney disease, and cardiovascular issues.
Short name
HbA1c
Frequently asked questions
How often should I get an HbA1c test?
What factors can affect my HbA1c result?
Can lifestyle changes impact my HbA1c?
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