Is my HbA1c (Hemoglobin A1C) normal?
Free blood test checker · Standard + longevity-optimal ranges
What is a normal HbA1c level?
HbA1c measures your average blood sugar over the past 2-3 months by reflecting the percentage of hemoglobin with glucose attached. It's the gold standard for diabetes screening. Normal is below 5.7%, prediabetes 5.7-6.4%, diabetes 6.5%+. Chronically elevated HbA1c drives the formation of advanced glycation end-products (AGEs), which cross-link collagen, stiffen blood vessels, and accelerate biological aging. Centenarian studies show exceptional longevity correlates with HbA1c maintained at 4.8-5.2%.
| Range | Values |
|---|---|
| Standard Reference | 4–5.7 % |
| Optimal | 4–5.4 % |
| Longevity Optimal | 4.8-5.2% |
| High Risk | > 6.5 % |
What causes abnormal HbA1c levels?
Elevated HbA1c is caused by chronically high blood sugar from insulin resistance, excess refined carbohydrate intake, sedentary lifestyle, obesity (especially visceral fat), chronic stress, poor sleep quality, and genetic predisposition to type 2 diabetes. Certain medications like corticosteroids can also raise blood sugar.
When should you see a doctor?
See your doctor if your HbA1c is 5.7% or above (prediabetes range), if you have symptoms like increased thirst, frequent urination, or unexplained fatigue, or if you have a family history of diabetes. If already diagnosed with diabetes, work with your doctor to keep HbA1c below your target (typically under 7%).
HbA1c and longevity
HbA1c is one of the most powerful biomarkers linking metabolic health to biological aging. Advanced glycation end-products (AGEs) formed by chronic hyperglycemia cross-link collagen fibers, causing vascular stiffness, endothelial dysfunction, and accelerated organ aging. Centenarian studies consistently show that individuals who maintain HbA1c between 4.8-5.2% throughout life have the strongest longevity outcomes. However, there is a U-shaped mortality curve — overly aggressive glucose lowering in frail or elderly populations can increase hypoglycemic events and worsen outcomes. The sweet spot for most healthy adults is optimizing HbA1c through metabolic fitness (exercise, body composition, sleep) rather than pharmacological suppression alone.
Where to get a HbA1c test
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Related biomarkers
These biomarkers are often tested alongside HbA1c for a more complete picture.
Related calculators
Composite scores that use HbA1c as an input.
Frequently asked questions
What is a normal HbA1c level?
What are advanced glycation end-products (AGEs)?
Can HbA1c be lowered naturally?
How often should I check HbA1c?
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Sources: Reference ranges based on AHA/ACC, ADA, and AACE clinical guidelines. Biological variation data from Ricos/Westgard database. Longevity-optimal ranges reflect targets used by preventive and functional medicine practitioners.
Last reviewed: April 2026. This tool provides general health information and is not a substitute for professional medical advice, diagnosis, or treatment. Always consult your healthcare provider about your specific results.