Day and night glucose control using a hybrid closed loop system for the management of type 1 diabetes

Abstract

Closed loop insulin delivery investigation has moved to the outpatient setting. In this randomized cross-over trial, we compared sensor augmented pump therapy with threshold suspend (SAPT + LGS) to a closed loop system with meal announcement in a free living ambulatory setting in patients with type 1 diabetes. We used the Medtronic Hybrid Closed Loop (HCL) system consisting of a Medtronic MiniMed insulin pump, Medtronic MiniMed Enlite II glucose sensor, Medtronic MiniMed Minilink REAL time sensor, Medtronic MiniMed Translator, and an Android mobile device with the HCL algorithm (proportional integrative derivate minus insulin feedback and additional safety parameters). All participants were optimized prior to an initial 48 hr in-clinic training period, followed by 5 days as an outpatient with remote monitoring. 8 patients (all female, mean age 25 ys (13-40), length of diagnosis 14 ys (4.2-25.6), mean HbA1c 7.5% (6.70-8.2) were studied. To date we have completed 840 hours of HCL and 840 hours of SAPT + LGS in the ambulatory setting. The mean sensor glucose value during HCL over the 5 day period was 8.8 ± 3.1 mmol/L compared to 9.1 ± 3.3 mmol/L (p < 0.001) during SAPT + LGS. The percentage of time with a low glucose value ( < 3.9 mmol/L) was reduced to 1.55% using HCL from 3.51% during SAPT + LGS (p < 0.001). Percentage time spent in target range (4.0-10 mmol/L) was 67.9% for HCL vs 62.2% for SAPT + LGS (p < 0.001). We conclude that the Medtronic Hybrid Closed Loop (HCL) system delivers improved mean sensor glucose values, and reduces hypoglycaemia in free living conditions.