Compare two CGM exports

Drop two exports, from two sensors worn at the same time or from two different months, and see them side by side: average, GMI, time in range, variability and the 24-hour profile. Where the two overlap in time, we pair the readings and show how far apart the sensors read.

Unit
Export ADrop the first exportLibreView or Dexcom Clarity CSV, Stelo or Lingo export, SiBionics .xlsx, Apple Health export.zip or any glucose CSV.Choose a file
Export BDrop the second exportLibreView or Dexcom Clarity CSV, Stelo or Lingo export, SiBionics .xlsx, Apple Health export.zip or any glucose CSV.Choose a file

Runs in your browser. Nothing you type or drop here is uploaded.

How it is worked out

Each column: the same maths as the free CGM report (GMI: Bergenstal 2018; time in range: Battelino 2019; CV: Danne 2017) Overlap: each A reading paired with the nearest B reading within 5 minutes; gap = |B − A| ÷ ((A + B) ÷ 2)

Sources

  1. Bergenstal et al. 2018. Diabetes Care 41(11):2275-2280. Glucose Management Indicator (GMI): a new term for estimating A1C from continuous glucose monitoring.
  2. Battelino et al. 2019. Diabetes Care 42(8):1593-1603. International consensus on time in range.
  3. Danne et al. 2017. Diabetes Care 40(12):1631-1640. International consensus on use of continuous glucose monitoring.
  4. Hengist et al. 2024. American Journal of Clinical Nutrition. Meal responses on two sensors at once.
  5. Hutchins et al. 2025. American Journal of Clinical Nutrition. Libre 2 compared with finger-prick tests.

Glucose tools

See it all from your export

The free CGM report reads the whole file: your 24-hour profile (AGP), time in range, GMI, variability, your biggest rises and overnight sensor pressure.

Open the free CGM report

Questions people ask

How do I compare two CGM sensors worn at the same time?
Export the days you wore both, from each sensor’s app or website (LibreView, Dexcom Clarity, Stelo, Lingo, SiBionics or Apple Health), and drop one file on each side above. Every reading of one sensor is paired with the other’s reading within 5 minutes, and you see the average difference, the average gap and which sensor tends to read higher.
How do I compare this month’s CGM data with last month’s?
Export each month separately and drop them side by side. You see average glucose, GMI, time in range on two bands, variability and the 24-hour profile for each, with the difference.
Why do two CGMs show different numbers?
Each sensor sits in a different spot, has its own calibration and its own delay behind blood glucose. Studies wearing two brands at once found they disagree on the same meals (Hengist et al. 2024), and some read higher than finger-pricks on average (Hutchins et al. 2025).
Is my data uploaded?
No. Both files are read by your browser on your device. Nothing is sent to HealthOS or anyone else. We count anonymous events like “a comparison was made”, never a reading.

More free glucose tools

GMI calculatorTime in range calculatorGlucose variability (CV) calculatorMeal spike checkermg/dL ↔ mmol/L converter
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Information, not a diagnosis. HealthOS is a wellness product, not a medical device: these numbers can’t tell you whether anything needs treatment. Talk to a doctor about your results.