Hemoglobin A1c (HbA1c) with calculated mean glucose concentration
This test measures your average blood sugar levels over the past 2–3 months, linked to your hemoglobin protein. It helps assess long-term diabetes control and glucose metabolism.
["HbA1c reflects your average blood sugar, a key measure for diabetes management."]
Key facts at a glance
- LOINC
- 105274-5
- Short code
- Hgb BldV Calc-mCnc
- Synonyms
- Hgb BldV 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
How This Test Works
Your blood sample is analyzed to determine the percentage of hemoglobin molecules that are coated with glucose. This percentage (HbA1c) correlates with your average blood sugar levels over time. The test also calculates a derived mean glucose concentration, which provides additional insight into your glucose trends.
Why It Matters for Diabetes
HbA1c is a critical tool for diagnosing diabetes, monitoring treatment effectiveness, and preventing complications. It gives doctors a clearer picture of how well your blood sugar is managed over months, unlike daily blood sugar checks.
Sample Collection and Preparation
A small blood sample is drawn from your arm, typically during a routine visit. No special preparation is needed, but fasting is not required for this test. The sample is processed to separate hemoglobin from other blood components for accurate measurement.
What to Expect Before the Test
You may experience slight discomfort from the needle, but it usually fades quickly. If you’re nervous, let your healthcare provider know—they can offer tips to make the process more comfortable.
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 and Diabetes Management
Short name
HbA1c with glucose mean
Frequently asked questions
HbA1c is used to diagnose prediabetes (when levels are slightly elevated) and diabetes (when levels are high). It helps doctors adjust medications, track progress, and identify patterns in your blood sugar control. Abnormal results may signal the need for lifestyle changes, medication adjustments, or further testing.
Can HbA1c be affected by other conditions? Yes, conditions like anemia, kidney disease, or certain medications (e.g., blood thinners) can influence HbA1c levels. If you have these conditions or take medications, let your doctor know—they may interpret your results differently.
Does fasting affect HbA1c? No, unlike some other blood tests, HbA1c does not require fasting. It measures long-term glucose trends, so timing around meals doesn’t impact the result.
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