Accuracy of Bolus and Basal Rate Delivery of Different Insulin Pump Systems

Insulin pumps are used for basal rate and bolus insulin delivery in patients with diabetes. In this in vitro study, accuracy of delivery of different commercial insulin pumps was evaluated. Accuracy of 10 different insulin pump systems (5 durable pumps with different insulin infusion sets and 1 patch pump) was tested with a microgravimetric method. Mean bolus accuracy of 25 successive 1 U boluses and of 12 successive 10 U boluses was assessed, and delivery time for 10 U boluses was measured. Basal rate accuracy at 1.0 U/h was evaluated for 72 h and for individual 1-h windows. Mean bolus delivery was within ±5% of target for both tested bolus sizes, but precision of individual boluses was higher with the larger boluses. Delivery times varied between the different pump models but agreed with the specifications of the respective manufacturers. Regarding basal rate accuracy, the total deviation for 72 h was very small in all pumps; however, larger deviations were observed during the first 12 h. For the patch pump, large variations between individual 1-h windows were observed. In general, all compared insulin pump systems showed a similar level of accuracy. Differences, especially between durable pumps and the patch pump, were observed when considering each hour of basal rate delivery separately.