Mean Absolute Relative Difference (MARD) is a standard metric used to evaluate the accuracy of continuous glucose monitoring systems, which gives the average amount a CGM sensor reading varies from the actual blood glucose. It is calculated by taking the average of the absolute relative differences between the glucose readings reported by the CGM system and corresponding reference measurements, typically obtained through laboratory analysis or blood glucose meters. A lower MARD value indicates greater accuracy, and it is commonly used in clinical research and regulatory evaluations to compare the performance of different CGM devices. It is also of note that MARD percentages can vary by person, even while using the same device.
MARD by device +DeviceMARDRelease yearNotesDexcom STS20.3%2006SUMMARY OF SAFETY AND EFFECTIVENESS DATA, DexCom STS, Food and Drug Administration, 24 March 2006, accessed 8 April 2025Dexcom Seven17%2007Dexcom G5 Advisory Committee Briefing Materials, Dexcom, Clinical Chemistry and Clinical Toxicology Devices Panel, 21 July 2016, accessed 8 February 2025Dexcom Seven Plus16%2010Dexcom G4 Platinum13.9%2012Dexcom G5 Mobile9%2015Dexcom G69%2018Dexcom G78.2%2022Dexcom G7 15-Day8%2024FreeStyle Libre 113.7%2014FreeStyle Libre 29.3%2020FreeStyle Libre 37.8%2022
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