Glucose Sensor Accuracy After Subcutaneous Glucagon Injections Near to Sensor Site

Integrated hormone delivery and glucose sensing is warranted, but system performance could be challenged by glucose sensor susceptibility to pharmacological interferences. The aim of this study was to compare sensor accuracy (Medtronic Enlite 2^®) after subcutaneous (s.c.) administration of low-dose glucagon near to versus remote from sensor site. Twelve adults with insulin-pump-treated type 1 diabetes wore two continuous glucose monitors (CGM_glucagon and CGM_control) placed on each side of the abdomen before, during, and after two overnight 14-h in-clinic visits. During each visit, a s.c. 100 μg glucagon injection was administered 2 cm next to the CGM_glucagon followed by another injection of 100 μg glucagon 2 h later at the same site. CGM performance was evaluated using 4-h in-clinic Yellow Spring Instrument (YSI) measurements and 3-day self-monitoring of blood glucose (SMBG) in free-living conditions. Using YSI as comparator, no difference in the median absolute relative difference (MARD) for CGM_glucagon (15.7%) and CGM_control (13.4%) was found (P = 0.195). Similarly, no difference in MARD was found between CGM_glucagon (11.0%) and CGM_control (6.2%) using SMBG as comparator (P = 0.148). Values in zone A + B of Clarke error grid analysis did not differ between CGM_glucagon and CGM_control using YSI (93.9% vs. 91.1%, P = 0.250) and SMBG (97.3% vs. 95.0%, P = 0.375) as reference measurement. The precision absolute relative deviation between sensors was 13.7%. Sensor accuracy was not significantly affected by administration of s.c. glucagon near to sensor site.