Adjustment of open-loop settings to improve closed-loop results in type 1 diabetes: A multicenter randomized trial

Eyal Dassau, Sue A. Brown, Ananda Basu, Jordan E. Pinsker, Yogish C. Kudva, Ravi Gondhalekar, Steve Patek, Dayu Lv, Michele Schiavon, Joon Bok Lee, Chiara Dalla Man, Ling Hinshaw, Kristin Castorino, Ashwini Mallad, Vikash Dadlani, Shelly K. McCrady-Spitzer, Molly McElwee-Malloy, Christian A. Wakeman, Wendy C. Bevier, Paige K. BradleyBoris Kovatchev, Claudio Cobelli, Howard C. Zisser, Francis J. Doyle

Research output: Contribution to journalArticlepeer-review

59 Scopus citations


Context: Closed-loop control (CLC) relies on an individual's open-loop insulin pump settings to initialize the system. Optimizing open-loop settings before using CLC usually requires significant time and effort. Objective: The objective was to investigate the effects of a one-time algorithmic adjustment of basal rate and insulin to carbohydrate ratio open-loop settings on the performance of CLC. Design: This study reports a multicenter, outpatient, randomized, crossover clinical trial. Patients: Thirty-seven adults with type 1 diabetes were enrolled at three clinical sites. Interventions: Each subject's insulin pump settings were subject to a one-time algorithmic adjustment based on 1 week of open-loop (i.e., home care) data collection. Subjects then underwent two 27-hour periods of CLC in random order with either unchanged (control) or algorithmic adjusted basal rate and carbohydrate ratio settings (adjusted) used to initialize the zone-model predictive control artificial pancreascontroller. Subject'sfollowedtheirusualmeal-planandhadanunannouncedexercise session. Main Outcomes and Measures: Time in the glucose range was 80-140 mg/dL, compared between both arms. Results: Thirty-two subjects completed the protocol. Median time in CLC was 25.3 hours. The median time in the 80-140 mg/dl rangewassimilar in both groups (39.7% control,44.2%adjusted). Subjects in both arms of CLC showed minimal time spent less than 70 mg/dl (median 1.34% and 1.37%, respectively). There were no significant differences more than 140 mg/dL. Conclusions: A one-time algorithmic adjustment of open-loop settings did not alter glucose control in a relatively short duration outpatient closed-loop study. The CLC system proved very robust and adaptable, with minimal (∼2%) time spent in the hypoglycemic range in either arm.

Original languageEnglish (US)
Pages (from-to)3878-3886
Number of pages9
JournalJournal of Clinical Endocrinology and Metabolism
Issue number10
StatePublished - Oct 1 2015

ASJC Scopus subject areas

  • Endocrinology, Diabetes and Metabolism
  • Biochemistry
  • Endocrinology
  • Clinical Biochemistry
  • Biochemistry, medical


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