Comparing Self Monitoring Blood Glucose Devices and Laboratory Tests: Over 25 Years Experience.

Self-monitoring blood glucose (SMBG) devices have been widely used in medical practice for decades. However, there are certain gaps between SMBG device readings and venous blood glucose levels. Here, 3,532 measurement data points were recorded over 25 years to compare SMBG device readings and venous blood glucose levels. The mean absolute difference (MAD) or the GAP was 10.9 mg/dL, and the mean absolute relative difference (MARD) was 8.3%. The absolute relative difference (ARD) (%) and absolute difference (AD or GAP) (mg/dL) coefficients of variation (CV) (%) of 100% indicate high variance between the capillary BG and venous true BG data. There was a slight skewing of MAD and MARD to the lower body mass index (BMI) side, the higher age side, and the female gender side. There were 41 data points that showed unacceptable gaps of over 50 mg/dL. Such large differences may cause incorrect medications or treatments. All healthcare providers should be aware of the gap between SMBG device readings and venous blood glucose levels.