Chapter 01 · The two units
Two ways to describe the same thing
HbA1c reflects the average amount of sugar attached to your red blood cells over roughly the past three months, reported as a percent. Estimated average glucose translates that same information into the mg/dL units you see on a glucose meter. The conversion comes from the A1c-Derived Average Glucose (ADAG) study, which related the two with the equation eAG (mg/dL) = 28.7 times A1c minus 46.7.1 An A1c of 7 percent works out to an average glucose of about 154 mg/dL.
| A1c | Estimated average glucose | ADA reference label |
|---|---|---|
| 5.6% or below | About 114 mg/dL or below | Below the prediabetes range |
| 5.7% to 6.4% | About 117 to 137 mg/dL | Prediabetes range |
| 6.5% or above | About 140 mg/dL or above | Diabetes range |
These are population reference ranges from the ADA, not a diagnosis. A clinician confirms with proper testing.
Chapter 02 · The fine print
What the conversion cannot do
The eAG is an average, so it hides the highs and lows that a continuous glucose monitor or fingersticks would show, and it can be skewed by conditions that affect red blood cells, such as anemia or recent blood loss. Most importantly, this tool does not diagnose anything. The ranges shown are population references; only a clinician, using appropriately collected lab tests and your history, can determine what your numbers mean for you. Individual results vary.
If your A1c is near or above the prediabetes range, that is a conversation to have with a clinician, not a conclusion to draw from this tool. A licensed physician interprets the result in context.
