Hemoglobin A1c (HbA1c)
Quest Diagnostics · Test Code 496
A blood test that reflects average glycemic exposure over the preceding several months.
 
What It Measures
The percentage of hemoglobin that is glycated (HbA1c).
 
Why It May Be Useful
HbA1c is used for screening and diagnosis of diabetes in appropriate patients and for monitoring longer-term glycemic control in people with diabetes. Interpretation should consider factors that can alter red blood cell turnover or hemoglobin structure.
 
Preparation
Quest lists no fasting requirement for standard HbA1c testing. Follow any additional instructions provided with your order.
 
Important Considerations
HbA1c does not show day-to-day glucose variability and can be misleading in some settings, including certain anemias, hemoglobin variants, recent blood loss or transfusion, and conditions that substantially alter red-cell lifespan.
 
Reference
Quest Diagnostics — Hemoglobin A1c, Test Code 496
This testing is intended to provide additional health information and does not by itself diagnose a medical condition or replace evaluation, diagnosis, or treatment by a qualified healthcare professional. Results should be interpreted in the context of medical history, symptoms, medications, and other clinically relevant information.