Community Answer

Answered by Dr. Emily Carter, MD

The HbA1c (Hemoglobin A1c) test measures the average blood glucose levels over the past 2-3 months. It is calculated based on the percentage of hemoglobin that is glycated (has glucose attached to it). Here’s how it works:

  • Blood Sample: A blood sample is taken, usually from a vein in your arm.
  • Lab Analysis: The sample is analyzed in a lab to determine the percentage of glycated hemoglobin.
  • Result Interpretation: The result is given as a percentage. The higher the percentage, the higher your average blood glucose levels have been.

HbA1c Ranges:

HbA1c (%) Interpretation

Below 5.7 Normal 5.7 - 6.4 Prediabetes 6.5 or above Diabetes

For example, an HbA1c of 7% corresponds to an estimated average glucose (eAG) of 154 mg/dL.

Formula for eAG:

The estimated average glucose (eAG) can be calculated using the formula:

eAG (mg/dL) = 28.7 × HbA1c - 46.7

This formula helps convert HbA1c percentages into average blood glucose levels, which can be easier to understand for daily management.

If you need to calculate your HbA1c, consult your healthcare provider for accurate testing and interpretation.

Last updated: 1/12/2025

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