Objective: Assess patient experience via semi-structured interviews after long-term outpatient use of closed loop control (CLC).

Methods: Eleven patients with T1D diagnosed for at least one year participated (10 females), with a mean (SD) age of 47.3 years (12.9), diabetes duration of 26.6 years (17.7), and pre-study HbA1c 7.6% (0.5) or 60 mmol/mol. The CLC system was inControl, composed of a CGM, insulin pump, and control algorithms housed on a smartphone. Participants used inControl for 8-weeks after which they were interviewed. Interviews followed a semi-structured format based on theories of technology acceptance. Numerical ratings were obtained for difficulty, complexity, trust, and long-term use probability on a 5-point Likert scale.

Results: Ratings were difficulty - 2.0 (0.8), complexity - 1.9 (0.8), trust - 3.8 (1.0), and 4) probability of long-term use - 3.3 (1.6). Difficult aspects of use were managing the three components and alarms for out of range BGs. The major complexities were finding ways to stop alarms and understanding insulin bolus calculation. Nine patients reported that the device was very useful and had improved BG control, including decreasing low BGs and reducing HbA1c. All reported “over-riding“ the device, most often to give more insulin for high BG correction, and also detaching the system at times to avoid alarms. Trust in the device was high, with 8 patients rating ≥ 4 but there was belief that not enough insulin was given for high BGs. Probability of long-term use varied, with the alarms and burden of multiple components as factors.

Conclusions: Patient-reported experiences varied across individuals. The majority did not find the system difficult or complex, found it useful for better BG control, and trusted it. However, there is need for technology improvement to reduce equipment burden and alarms. Findings indicate that users might benefit from patient education before device use to help them understand how the system calculates insulin doses.


L. Gonder-Frederick: Other Relationship; Self; HFS-Global LLC. S.A. Brown: Research Support; Self; Roche Diagnostics Corporation, Dexcom, Inc., Tandem Diabetes Care, Inc., Medtronic, Ascensia Diabetes Care, TypeZero Technologies, Inc.. J. Shepard: None. L.L. Kollar: None. B. Kovatchev: Consultant; Self; Sanofi-Aventis. Speaker's Bureau; Self; Dexcom, Inc.. Stock/Shareholder; Self; TypeZero Technologies, Inc.. Research Support; Self; Dexcom, Inc., Roche Diagnostics Corporation, Tandem Diabetes Care, Inc., Ascensia Diabetes Care.

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