Hemoglobin A1c (HbA1c) calculated from capillary blood glucose concentration
This test measures the average blood sugar level over the past 2–3 months by analyzing hemoglobin bound to glucose in your red blood cells.
["Helps track long-term blood sugar control for diabetes management."]
Key facts at a glance
- LOINC
- 33025-8
- Short code
- Hgb BldCoV Calc-mCnc
- Synonyms
- Hgb BldCoV Calc-mCnc
- 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
- Method
- calculated
- 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 This Test Matters
HbA1c is a key indicator of how well your blood sugar has been managed over time. Unlike daily blood glucose checks, it provides a broader picture of your average glucose levels, helping healthcare providers assess long-term diabetes control.
How It’s Done
A small blood sample is taken from your finger (capillary blood). The test measures the percentage of hemoglobin molecules that have glucose attached, which reflects your average blood sugar levels from the past 2–3 months.
What It Measures
HbA1c specifically quantifies the proportion of hemoglobin bound to glucose, expressed as a percentage. This value is calculated from your current blood glucose concentration, adjusted for factors like red blood cell lifespan.
What It Indicates
Higher HbA1c levels suggest poorer blood sugar control, while lower levels indicate better management. However, individual results depend on diet, activity, and other health factors.
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.
◆Associated findings1
Short name
HbA1c (Calculated)
Frequently asked questions
HbA1c is essential for diagnosing diabetes, monitoring treatment progress, and preventing complications like nerve damage or kidney disease. It helps healthcare providers adjust medications or lifestyle recommendations as needed.
How often should I get this test?
Does diet or exercise affect HbA1c results?
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