Mean absolute relative difference

Mean Absolute Relative Difference (MARD) is a standard metric used to evaluate the accuracy of continuous glucose monitoring systems,^[1] which gives the average amount a CGM sensor reading varies from the actual blood glucose.^[2] 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.^[3] 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.^[1]

MARD by device

Device	MARD	Release year	Notes
Dexcom STS	20.3%	2006	[4]
Dexcom Seven	17%	2007	[5]
Dexcom Seven Plus	16%	2010	[5]
Dexcom G4 Platinum	13.9%	2012	[6]
Dexcom G5 Mobile	9%	2015	[7]
Dexcom G6	9%	2018	[8]
Dexcom G7	8.2%	2022	[9]
Dexcom G7 15-Day	8%	2024	[10]
FreeStyle Libre 1	13.7%	2014	[11]
FreeStyle Libre 2	9.3%	2020	[12]
FreeStyle Libre 3	7.8%	2022	[13]