Comparison of the pharmacodynamics of protamine zinc insulin and insulin degludec and validation of the continuous glucose monitoring system iPro2 in healthy cats

Abstract With the aim to improve current therapeutic and monitoring options for diabetic cats, the present study compared pharmacodynamic parameters of protamine zinc insulin (PZI) and insulin degludec and validated the continuous glucose monitoring system (CGMS) iPro2 with Sof-sensor and Enlite-sensor focusing on the low glycemic range. Three doses (0.1, 0.2 and 0.3 IU/kg) of the two insulin preparations and the CGMS iPro2 with two different sensors were tested in six healthy cats. After each insulin administration, onset of action, time to glucose nadir and duration of action were calculated by measuring glucose concentrations with a portable blood glucose meter (PBGM). After sensor placement, paired PBGM and sensor glucose measurements were done and analytical and clinical accuracy were calculated according to the ISO 15197:2013 criteria. Onset of action, time to glucose nadir and glucose nadir were similar for both insulin formulations. Duration of action of insulin degludec was significantly longer than those of PZI at 0.1 IU/kg ( P  = 0.043) and 0.2 IU/kg ( P  = 0.043). Overall, 166/191 (87%) Sof-sensor measurements and 106/121 (88%) Enlite-sensor measurements met ISO criteria for analytical accuracy, and all sensor measurements fulfilled ISO criteria for clinical accuracy. Insulin degludec was well tolerated in healthy cats and showed longer duration of action than PZI. Further studies on the use of insulin degludec in diabetic cats might be recommended. Both sensors had good clinical accuracy, when used with the CGMS iPro2, but the analytical accuracy was below the minimum set by ISO 15197:2013.