Dynamic Interference Testing Results with the Dexcom G6 Continuous Glucose Monitoring Device

Background: Continuous glucose monitoring (CGM) is becoming a standard diagnostic procedure in people with diabetes. However, little is known about how glucose oxidase-based interstitial sensors react to potentially interfering substances. We report on in vitro dynamic interference testing with Dexcom G6 sensors. Methods: Using pressure liquid chromatography (HPLC) pump-controlled substance gradients, we exposed sensors to varying concentrations of 69 substances in triplicate using YSI Stat 2300 Plus as glucose reference. Results: Interference was assumed if the device showed more than ±10% bias over baseline, and it was seen for Dexcom G6 with the following substances: acetaminophen, dithiothreitol, ethyl alcohol, galactose, gentisic acid, hydroxyurea, l -cysteine, l -dopa, mannose, N -acetyl-cysteine, and uric acid. Additionally, sensors could not subsequently be calibrated for use after exposure to dithiothreitol, gentisic acid, l -cysteine, and mesalazine (sensor fouling). Interference testing identified several nutritional, pharmacological, and endogenous substances that biased the Dexcom G6 signal in vitro. Conclusions: The in vitro test protocol cannot replace appropriate clinical testing, but if confirmed clinically, such interferences should be considered when making treatment decisions using Dexcom G6 readings. More research on the interference behavior of CGM sensors is strongly recommended before using them broadly in automated insulin delivery systems with insulin pumps.