Improvements in Glycemic Control Achieved by Altering the t max Setting in the iLet® Bionic Pancreas When Using Fast-Acting Insulin Aspart: A Randomized Trial

Steven J. Russell, Courtney Balliro, Magnus Ekelund, Firas El-Khatib, Tina Graungaard, Evelyn Greaux, Mallory Hillard, Rabab Z. Jafri, Naveen Rathor, Raj Selagamsetty, Jordan Sherwood, Edward R. Damiano

Research output: Contribution to journalArticlepeer-review

9 Scopus citations


Introduction: We investigated the safety of, and glucose control by, the insulin-only configuration of the iLet® bionic pancreas delivering fast-acting insulin aspart (faster aspart), using the same insulin-dosing algorithm but different time to maximal serum drug concentration (tmax) settings, in adults with type 1 diabetes. Methods: We performed a single-center, single-blinded, crossover (two 7-day treatment periods) escalation trial over three sequential cohorts. Participants from each cohort were randomized to a default tmax setting (t65 [tmax = 65 min]) followed by a non-default tmax setting (t50 [tmax = 50 min; cohort 1], t40 [tmax = 40 min; cohort 2], t30 [tmax = 30 min; cohort 3]), or vice versa, all with faster aspart. Each cohort randomized eight new participants if escalation-stopping criteria were not met in the previous cohort. Results: Overall, 24 participants were randomized into three cohorts. Two participants discontinued treatment, one due to reported ‘low blood glucose’ during the first treatment period of cohort 3 (t30). Mean time in low sensor glucose (< 54 mg/dl, primary endpoint) was < 1.0% for all tmax settings. Mean sensor glucose in cohorts 1 and 2 was significantly lower at non-default versus default tmax settings, with comparable insulin dosing. The mean time sensor glucose was in range (70–180 mg/dl) was > 70% for all cohorts, except the default tmax setting in cohort 1. No severe hypoglycemic episodes were reported. Furthermore, there were no clinically significant differences in adverse events between the groups. Conclusion: There were no safety concerns with faster aspart in the iLet at non-default tmax settings. Improvements were observed in mean sensor glucose without increases in low sensor glucose at non-default tmax settings. Trial Registration:, NCT03816761.

Original languageEnglish (US)
Pages (from-to)2019-2033
Number of pages15
JournalDiabetes Therapy
Issue number7
StatePublished - Jul 2021


  • Algorithm
  • Automated delivery
  • Bionic pancreas
  • Faster aspart
  • Glucose control
  • Insulin
  • Type 1 diabetes

ASJC Scopus subject areas

  • Internal Medicine
  • Endocrinology, Diabetes and Metabolism


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