Reference ranges
A1C reference range
Reference ranges describe the interval a laboratory prints next to your result. They are not a diagnosis of what is “normal” for you personally — your clinician interprets results in context.
General biomarker education — not personalized medical advice. Learn more
What A1C measures
Glucose in the bloodstream can attach to hemoglobin in red blood cells. A1C (also called hemoglobin A1c, HbA1c, or glycated hemoglobin) estimates the percentage of hemoglobin that is glycated. Because red cells live for months, clinicians often use it as a longer-window view than a single fasting glucose.
Why ranges differ
Laboratories set their own reference intervals using their methods, equipment, and population data. That is why the range on your Quest report may differ from a LabCorp report — always use the interval printed on your source document.
Common units
A1C is often reported in %. Confirm units on your original report before comparing values across time.