Closed-loop insulin delivery in inpatients with type 2 diabetes: a randomised, parallel-group trial

Background We assessed whether fully closed-loop insulin delivery (the so-called artifi cial pancreas) is safe and eff ective compared with standard subcutaneous insulin therapy in patients with type 2 diabetes in the general ward. Methods For this single-centre, open-label, parallel-group, randomised controlled trial, we enrolled patients aged 18 years or older with type 2 diabetes who were receiving insulin therapy. Patients were recruited from general wards at Addenbrooke's Hospital, Cambridge, UK. Participants were randomly assigned (1:1) by a computer-generated minimisation method to receive closed-loop insulin delivery (using a model-predictive control algorithm to direct subcutaneous delivery of rapid-acting insulin analogue without meal-time insulin boluses) or conventional subcutaneous insulin delivery according to local clinical guidelines. The primary outcome was time spent in the target glucose concentration range of 5.6-10.0 mmol/L during the 72 h study period. Analyses were by intention to treat. This trial is registered with ClinicalTrials. gov, number NCT01774565. Findings Between Feb 20, 2015, and March 24, 2016, we enrolled 40 participants, of whom 20 were randomly assigned to the closed-loop intervention group and 20 to the control group. The proportion of time spent in the target glucose range was 59.8% (SD 18.7) in the closed-loop group and 38.1% (16.7) in the control group (diff erence 21.8% [ 95% CI 10.4-33.1]; p=0.0004). No episodes of severe hypoglycaemia or hyperglycaemia with ketonaemia occurred in either group. One adverse event unrelated to study devices occurred during the study (gastrointestinal bleed). Interpretation Closed-loop insulin delivery without meal-time boluses is eff ective and safe in insulin-treated adults with type 2 diabetes in the general ward.