HbA1c — Normal Range & Interpretation

Clinical Context

Hemoglobin A1C (HbA1c) reflects average blood glucose over the prior 2-3 months by measuring the percentage of hemoglobin that has glucose attached. It's the primary laboratory marker used to screen for and monitor diabetes, and it's the test the AANP boards most often use to frame diabetes-related vignettes.

A value below 5.7 percent is considered normal. Values between 5.7 and 6.4 percent indicate prediabetes, and a value of 6.5 percent or higher on two separate tests confirms the diagnosis of diabetes. Once a patient has diabetes, goal A1C is typically below 7 percent for most adults, with individualized targets for older adults, those with comorbidities, and those with a short life expectancy.

Classic AANP vignette: interpret an A1C in the context of a clinical presentation (new diabetes diagnosis, inadequate control, conflicting glucose and A1C results). Know which patients need A1C screening, at what interval, and when the test can be misleading — notably hemolytic anemia, recent transfusion, and hemoglobinopathies can falsely lower or raise the reading.

Related Labs

• ESR — mm/hr
• CRP — mg/dL
• hs-CRP — mg/L
• Uric Acid — mg/dL
• Iron (serum) — μg/dL

Sources

• MedlinePlus
• AAFP