A Multicenter Randomized Trial Evaluating the Insulin-Only Configuration of the Bionic Pancreas in Adults with Type 1 Diabetes

Objective: To evaluate the insulin-only configuration of the iLet® bionic pancreas (BP) using insulin aspart or insulin lispro in adults with type 1 diabetes (T1D). Methods: In this multicenter, randomized, controlled trial, 161 adults with T1D (18-79 years old, baseline HbA1c 5.5%-13.1%, 32% using multiple daily injections, 27% using a pump without automation, 5% using a pump with predictive low glucose suspend, and 36% using a hybrid closed loop system before the study) were randomly assigned 2:1 to use the BP (N = 107) with insulin aspart or insulin lispro (BP group) or a standard-of-care (SC) control group (N = 54) using their usual insulin delivery plus continuous glucose monitoring (CGM). The primary outcome was HbA1c at 13 weeks. Results: Mean HbA1c decreased from 7.6% ± 1.2% at baseline to 7.1% ± 0.6% at 13 weeks with BP versus 7.6% ± 1.2% to 7.5% ± 0.9% with SC (adjusted difference =-0.5%, 95% confidence interval-0.6% to-0.3%, P < 0.001). Over 13 weeks, mean time in range 70-180 mg/dL (TIR) increased by 11% (2.6 h/d) and mean CGM glucose was reduced by 16 mg/dL with BP compared with SC (P < 0.001). Improvement in these metrics was seen during the first day of BP use and by the end of the first week reached levels that remained relatively stable through 13 weeks. Analyses of time >180 mg/dL, time >250 mg/dL, and standard deviation of CGM glucose all favored the BP group (P < 0.001). The CGM-measured hypoglycemia was low at baseline (median time <54 mg/dL of 0.21% [3 min/d] for the BP group and 0.11% [1.6 min/d] for the SC group) and not significantly different between groups over the 13 weeks (P = 0.51 for time <70 mg/dL and 0.33 for time <54 mg/dL). There were 7 (6.5% of 107 participants) severe hypoglycemic events in the BP group and 2 events in the SC group (1.9% of 54 participants, P = 0.40). Conclusions: In adults with T1D, use of the BP with insulin aspart or insulin lispro improved HbA1c, TIR, and hyperglycemic metrics without increasing CGM-measured hypoglycemia compared with standard of care. Clinical Trial Registry: Clinicaltrials.gov; NCT04200313.