A1C Value for Average Blood Sugar of 104 mg/dL
Based on the most recent and highest quality evidence, an average blood glucose level of 104 mg/dL corresponds to an A1C of approximately 5.2%. 1
Relationship Between A1C and Average Blood Glucose
The correlation between A1C and average blood glucose has been well established through clinical research:
According to the American Diabetes Association's Standards of Care (2024), the relationship between A1C and average glucose is based on the international A1C-Derived Average Glucose (ADAG) study, which showed a strong correlation (r = 0.92) between these measurements 1
The ADAG study collected approximately 2,700 glucose measurements over 3 months per A1C measurement in 507 adults with type 1, type 2, and no diabetes 1, 2
Specific A1C Values and Corresponding Average Glucose Levels
The American Diabetes Association provides a standardized conversion table:
- An A1C of 5% corresponds to an estimated average glucose (eAG) of 97 mg/dL (range 76-120 mg/dL) 1
- An A1C of 6% corresponds to an eAG of 126 mg/dL (range 100-152 mg/dL) 1
For an average blood glucose of 104 mg/dL, we can interpolate between these values:
- Since 104 mg/dL falls between 97 mg/dL (A1C 5%) and 126 mg/dL (A1C 6%), the corresponding A1C would be approximately 5.2% 1
Clinical Significance
Understanding this relationship has important clinical implications:
- An A1C of 5.2% is within the normal range (below 5.7%), indicating no diabetes or prediabetes 1
- For reference, prediabetes is defined as A1C between 5.7-6.4% 1
- Diabetes is diagnosed when A1C is ≥6.5% 1
Factors That May Affect A1C Interpretation
It's important to note that certain conditions can affect the accuracy of A1C measurements:
- Conditions affecting red blood cell turnover (hemolytic anemia, recent blood transfusion, etc.) may cause discrepancies between A1C and true mean glycemia 1
- Hemoglobin variants must be considered when A1C does not correlate with blood glucose monitoring levels 1
- Racial/ethnic differences may exist in the relationship between A1C and average glucose, with some studies showing higher A1C values in African Americans compared to non-Hispanic whites for the same mean glucose concentration 1
Mathematical Relationship
The linear regression equation from the ADAG study allows calculation of estimated average glucose from A1C:
- eAG (mg/dL) = 28.7 × A1C - 46.7 2
- Using this equation in reverse: A1C = (eAG + 46.7) ÷ 28.7
- For an average glucose of 104 mg/dL: A1C = (104 + 46.7) ÷ 28.7 = 5.25% 2
This mathematical approach confirms our interpolation from the standardized table, showing that an average blood glucose of 104 mg/dL corresponds to an A1C of approximately 5.2%.