The Usability of a Hybrid Closed-Loop Insulin Delivery System: Simulated Use Studies of the t:slim X2 Pump With Control-IQ Technology

Preston Sobel, Nancy Terjung, Betsy Dokken, Ian Cadieux, Garrett Marin, Jason Farnan


To assess the usability and safety of a touchscreen, wearable insulin pump with an operating system that automatically adjusts insulin delivery based on a) predicted continuous glucose monitoring (CGM) readings and b) user input that informs the insulin pump of food intake and activity levels.


70 participants, composed of insulin pump users and multiple daily injection (MDI) users, completed the usability studies. The participants were given real-life scenarios as context for simulated use tasks and knowledge tests.


The average SUS scores for the formative and summative tests were identical at 84, indicating a high user satisfaction (typical scores 65-75). Task completion rates of 93% and 96% were observed, respectively.


The findings indicate that the t:slim X2 insulin pump with an advanced hybrid closed-loop insulin delivery system from Tandem Diabetes Care, in simulated use, was both intuitive and safe to use.