Clinical Significance
Estimated average glucose (eAG) translates HbA1c into units that are more familiar to patients and clinicians who routinely interpret daily glucose readings.
It helps connect long-term glycemic exposure with average glucose values, making HbA1c results easier to understand in practical terms.
Formula and Example
This calculator uses the ADAG/NGSP equation: eAG (mg/dL) = 28.7 × HbA1c - 46.7.
To convert the result to mmol/L, the mg/dL value is divided by 18.0182.
Example: if HbA1c is 7.0%, then eAG is about 154 mg/dL, which is about 8.6 mmol/L.
Reference Interpretation
Below Prediabetes Threshold:
HbA1c below 5.7%. This is generally below the usual prediabetes threshold, though interpretation depends on the clinical context.
Prediabetes Range:
HbA1c from 5.7% to 6.4%. This falls within the commonly used prediabetes range.
Diabetes Range:
HbA1c 6.5% or higher. This falls within the commonly used diabetes diagnostic range, but diagnosis should follow established clinical criteria.
Clinical Notes
eAG is an estimate derived from HbA1c and should be interpreted carefully in situations where HbA1c may be less reliable.
- Interpret with caution in anemia, hemoglobin variants, recent transfusion, pregnancy, or altered red cell turnover.
- Use HbA1c and eAG as part of the broader clinical picture, not in isolation.
- Daily glucose readings and CGM data may differ from eAG because eAG is a long-term estimate.
- This tool is useful for communication and interpretation, especially when comparing HbA1c with familiar glucose units.