Comparative Dose Accuracy of Durable and Patch Insulin Pumps Under Laboratory Conditions

Recent studies demonstrate variable results of the accuracy with which patch pumps infuse insulin. Aim of this evaluation was to measure dose accuracies of the patch pump mylife™ OmniPod^® (OP) in comparison with the durable insulin pump MiniMed^® 640G (MM) simulating real-life clinical situations under laboratory conditions. Thirty-two OP and 15 MM were tested using insulin aspart at five different boluses (0.5, 1, 5, 10, and 15 international units [IU]) and three basal rates (0.2, 0.6, and 1.8 IU/h) at different time points during a 70 h investigation period. Owing to malfunctions only 22 OP and 11 MM could be analyzed. Dose accuracy was measured by an experimental setting based on IEC 60601-2-24:2012 with determination of weight differences of insulin collection tubes before and after experiments using a precision scale. A maximal tolerance of ±5% for boluses and basal rates was considered adequate according to IEC 60601-2-24:2012. For the five boluses, the percentages of measurement results within the ±5% accuracy threshold were as follows: OP (18.6%, 26.5%, 89.0%, 96.0%, and 96.0%); MM (21.7%, 44.1%, 88.1%, 98.3%, and 100.0%). Both pumps were more accurate at higher bolus volumes (5, 10, and 15 IU), later bolus periods, and if the accuracy threshold was lowered to <10%, <15%, or >15%. For the three basal rates, the percentages within the ±5% accuracy threshold were as follows: OP (66.7%, 22.7%, and 16.7%); MM (14.3%, 0.0%, and 0.0%). This study demonstrates low accuracy for basal rates and single bolus deliveries at low insulin doses for both pump models. Clinicians should be aware of this variability when initiating insulin pump therapy especially in insulin-sensitive patients with low insulin dose requirements.