938-P: Dynamic Interference Testing Results with the Dexcom G6 Continuous Glucose Monitoring Device

Background: Continuous glucose monitoring (CGM) by means of needle sensors is becoming a standard option to gather the necessary glucose information for treatment of patients with type 1 and type 2 diabetes mellitus. Little is known, however, about the reaction of the glucose oxidase-based sensor technologies to potentially interfering nutritional, endogeneous or pharmaceutical substances. Here we report on results obtained with the Dexcom G6 needle sensor with our in-vitro dynamic intererence testing method. Method: We used HPLC pump-controlled substance gradients to expose Dexcom G6 needle sensors in a 3D-printed test cartridge to varying concentrations of potentially interfering substances at a fixed glucose concentration of 200 mg/dL. We tested 68 substances in triplicate using YSI Stat 2300 Plus as the glucose reference method. Interference was assumed if a CGM needle sensor showed more than ±10% difference from baseline with a tested substance at the given test concentration. Results: Interference was seen with the following substances: acetaminophen (>+100% bias from baseline), hydroxyurea (>+100%), uric acid (+33%), mannose (+20%), N-acetyl-cysteine (+18%), gentisic acid (+18%), galactose (+17%), ethyl alcohol (+12%), L-dopa (+11%), dithiothreitol (−18%), L-cysteine (−25%), while no interference was seen with other tested substances. In addition, the needle sensors subsequently ceased to operate when exposed to dithiothreitol, L-cysteine, gentisic acid, and mesalazine (suspected sensor fouling). Conclusions: Employing our standardized dynamic interference testing protocol, several nutritional and pharmacological substances were identified as influencing the Dexcom G6 signal. If confirmed by clinical trials, such interference will have to be considered when making treatment decisions using Dexcom G6 results in daily routine care. Disclosure A.Pfützner: Consultant; Novo Nordisk A/S, Research Support; LifeScan Diabetes Institute, Speaker's Bureau; AstraZeneca, Stock/Shareholder; Lifecare A/S, Diakard. H.Jensch: None. G.Srikanthamoorthy: None. C.Kuhl: None. S.J.Setford: Employee; LifeScan Scotland Ltd. M.Grady: Employee; Lifescan. E.H.Holt: Employee; LifeScan Inc. N.Thomé: None. Funding European Union’s Horizon 2020 Research and Innovation Program (951933); LifeScan Global Corporation