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Compare Freestyle Libre avg to A1C-Hplc

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  • Compare Freestyle Libre avg to A1C-Hplc

    I've been using the Libre CGM for a few months now, and I just got the first Hemoglobin A1C-Hplc results to be able to compare them directly. The difference is shocking!

    Libre 90 day avg = 99 mg/dL
    Hemoglobin A1C-Hplc = 128 mg/dL (6.1%)

    Even looking at the averages for individual weeks, the highest is 110 - far lower than 128. I've actually been trying to increase my carb intake to avoid the hypoglycemic events reported by Libre. But I don't have any symptoms of hypoglycemia, and the reason is probably that the CGM is reporting values much lower than the actual values.

    It would be nice if we could start compiling data from Libre users comparing their CGM reported averages vs lab results to see just how accurate (or inaccurate) it really is?

  • #2
    I believe CGMs need to be calibrated to a blood test, and assuming you did that, there is still a significant source of potential error. A1c assumes a 90 day life span of red blood cells. That can vary. Peter Attia discusses it here. Scroll down to the section on A1c.