The Insulin-only Bionic Pancreas (BP) Pivotal Trial compared the BP initialized only with body weight vs. standard-of-care (SC) . The BP autonomously determines all insulin doses. Meals are announced without carbohydrate counting. For adults aged 19-75 the mean adjusted difference of HbA1c at 13 weeks between BP and SC was -0.5% (95% CI: -0.6, -0.3, P<0.001) ; percent of time <54 mg/dl was not different between groups. Focus groups were conducted among BP users at the trial’s end.

Adults reported improved time in range and A1c. Many reported it corrected highs well; others felt it took too long. Some experienced fewer lows; others reported more, stating the algorithm was too aggressive in correcting highs. Concerns were raised about the inability to prevent lows even when predicted. Many experienced improved glycemia at night, improved sleep and waking up in target range; some found night-time lows negatively impacted sleep. Many reported difficulties suspending insulin to prevent lows, leading to less exercise during the trial. Meal announcements were appreciated, with increased freedom to eat without guilt, but most wished for snack announcements. Some found challenges managing high-fat foods and not having an extended bolus.

Many reported decreased emotional, cognitive and management burden with less worry, guilt, and burnout due to increased TIR and no need to carbohydrate count. Some found increased burden due to increased lows, and increased time filling cartridges and changing infusion sites. Some trusted the BP immediately, felt it learned their body quickly, and appreciated the automation. Others found waiting for corrections intolerable, engaging in either over-treating lows or administering external insulin for highs. Not knowing insulin-on-board was difficult for some.

System-specific concerns included: cartridge capacity, short tubing, no clip, poor back-lighting, the screen timing out quickly, and not being waterproof. Gathering patient perspectives offers insights into learning and using the BP as well as the psychosocial impact of the BP which can be used to guide future innovations.


K. P. Garza: None. K. R. Howard: None. J. Weissberg-benchell: None. M. Feldman: None. Bionic pancreas group: n/a.


National Institute of Diabetes Digestive and Kidney Disease (#1UC4DK108612-01)

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