Hemoglobin A1c (HbA1c) Glycosylated Hemoglobin
This test measures the average blood sugar levels over the past 2 to 3 months by tracking how much of your hemoglobin—a protein in red blood cells—is attached to sugar (glucose). It helps doctors assess long-term blood sugar control, especially important for managing diabetes.
["HbA1c reflects your blood sugar trends over time, aiding diabetes management and risk assessment."]
Key facts at a glance
- LOINC
- 97506-0
- Short code
- GLUCOSEMANAGEMENTINDICATOR
- Synonyms
- —
- Category
- glucose
- Sample
- serum
- Container
- Red-top tube (SST)
- Units
- N/A
- Ref low
- 70
- Ref high
- 100
- Critical range
- 50 N/A – 400 N/A
- Fasting
- true
- Population
- adult
- Sex
- all
- Age range
- 18–65 years
- Method
- calculated
- CPT
- 82947
- SNOMED
- 260395008
- 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
Why HbA1c Matters for Diabetes Management
Unlike daily blood sugar checks, HbA1c provides a broader picture of how well your diabetes is controlled over time. It’s a key tool for doctors to adjust treatment plans, such as medication or diet, to keep blood sugar levels stable and reduce complications like nerve damage or kidney issues.
How HbA1c Works in Your Body
HbA1c forms when glucose attaches to hemoglobin inside your red blood cells. Since red blood cells live for about 3 months, this test reflects your average blood sugar during that period. It doesn’t measure blood sugar at a single moment but instead gives a snapshot of your glucose control over time.
What Normal HbA1c Levels Indicate
While specific ranges vary by health condition, HbA1c levels are typically interpreted in relation to your diagnosis. For example, people with diabetes may aim for levels below a certain threshold to minimize risks. Your doctor will interpret results based on your individual health goals.
How HbA1c Differs from Daily Blood Sugar Tests
Unlike fingerstick blood sugar tests (e.g., fasting glucose or random glucose), HbA1c doesn’t depend on when you last ate or drank. It’s unaffected by short-term fluctuations and provides a consistent measure of long-term glucose exposure, making it ideal for tracking trends over months.
Reference range
Fasting: 70-100 mg/dLN/A
Fasting for 8-12 hours required. Water is permitted. Avoid chewing gum and smoking before the test.
Clinical interpretation
How abnormal results are interpreted and what conditions they suggest.
HbA1c is critical for diagnosing diabetes (when levels are consistently high) and evaluating treatment effectiveness. It also helps detect prediabetes (elevated but not yet diabetic levels) and assesses risks for long-term complications like heart disease or vision problems. Regular monitoring with HbA1c can improve outcomes by prompting timely lifestyle or medical adjustments.
Short name
HbA1c
Frequently asked questions
What does an abnormal HbA1c result mean?
Can HbA1c be affected by factors other than diabetes?
How often should I get an HbA1c test?
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