. We have shown that fully closed-loop insulin delivery does not increase the risk of hypoglycemia despite improved glycemic control and there were no episodes of severe hypoglycemia during closed-loop therapy. The study cohort spent very little time in hypoglycemia during both intervention periods.
Training and maintenance of study devices by participants was acceptable. One participant withdrew because of difficulty managing the devices, whereas all other participants were able to manage the devices independently and reported a high degree of satisfaction while using the closed-loop system. All participants reported that they were happy to have their glucose levels controlled automatically by the system, and 89% reported that they spent less time managing their diabetes overall.
The limitations of the study are that study participants were recruited from a single center and one general practice, and the group was not ethnically diverse, with only one participant not of white ethnicity. Although the present study demonstrated glycemic benefits over the 8-week intervention period, the results should not be generalized beyond this period. The washout period of 2–4 weeks is short for measuring HbA1c.
Ethical and regulatory approvals were obtained from the London-Stanmore Ethics Committee and the Medicines and Healthcare Products Regulatory Agency. The study protocol is provided in the Supplementary Information. The safety aspects of the trial were overseen by an independent data and safety monitoring board. The study is registered with ClinicalTrials.gov .