2 month evening and night closed-loop glucose control in patients with type 1 diabetes under free-living conditions: a randomised crossover trial

Background An artificial pancreas (AP) that can be worn at home from dinner to waking up in the morning might be safe and efficient for first routine use in patients with type 1 diabetes. We assessed the effect on glucose control with use of an AP during the evening and night plus patient-managed sensor-augmented pump therapy (SAP) during the day, versus 24 h use of patient-managed SAP only, in free-living conditions. Methods In a crossover study done in medical centres in France, Italy, and the Netherlands, patients aged 18-69 years with type 1 diabetes who used insulin pumps for continuous subcutaneous insulin infusion were randomly assigned to 2 months of AP use from dinner to waking up plus SAP use during the day versus 2 months of SAP use only under free-living conditions. Randomisation was achieved with a computer-generated allocation sequence with random block sizes of two, four, or six, masked to the investigator. Patients and investigators were not masked to the type of intervention. The AP consisted of a continuous glucose monitor (CGM) and insulin pump connected to a modified smartphone with a model predictive control algorithm. The primary endpoint was the percentage of time spent in the target glucose concentration range (3.9-10.0 mmol/L) from 2000 to 0800 h. CGM data for weeks 3-8 of the interventions were analysed on a modified intention-to-treat basis including patients who completed at least 6 weeks of each intervention period. The 2 month study period also allowed us to asses HbA(1c) as one of the secondary outcomes. This trial is registered with ClinicalTrials.gov, number NCT02153190. Findings During 2000-0800 h, the mean time spent in the target range was higher with AP than with SAP use: 66.7% versus 58.1% (paired difference 8.6% [95% CI 5.8 to 11.4], p<0.0001), through a reduction in both mean time spent in hyperglycaemia (glucose concentration >10.0 mmol/L; 31.6% vs 38.5%; -6.9% [-9.8% to -3.9], p<0.0001) and in hypoglycaemia (glucose concentration <3.9 mmol/L; 1.7% vs 3.0%; -1.6% [-2.3 to -1.0], p<0.0001). Decrease in mean HbA(1c) during the AP period was significantly greater than during the control period (-0.3% vs -0.2%; paired difference -0.2 [95% CI -0.4 to -0.0], p=0.047), taking a period effect into account (p=0.0034). No serious adverse events occurred during this study, and none of the mild-to-moderate adverse events was related to the study intervention. Interpretation Our results support the use of AP at home as a safe and beneficial option for patients with type 1 diabetes. The HbA(1c) results are encouraging but preliminary.