medwireNews: A randomized trial shows the feasibility of closed-loop insulin delivery controlled by an algorithm on a user’s phone rather than in their pump, but also highlights issues with connectivity.
“Mobile closed-loop control can be an appealing alternative to artificial pancreas systems with control algorithms embedded in the insulin pump, offering certain potential benefits such as more elaborate user interface, portability across devices, and improved user experience,” say John Lum (Jaeb Center for Health Research, Tampa, Florida, USA) and study co-authors.
They also note that people with type 1 diabetes, particularly adolescents, can be reluctant to use their insulin pumps in public, but are willing to use mobile phones, so mobile control may improve uptake of artificial pancreas systems.
However, their trial findings also highlight a major barrier, with the mobile-controlled system remaining in active closed-loop mode only 69% of the time. These “disruptions were primarily due to lost wireless signal,” the team writes in Diabetes Care.
But despite this, during the 3-month follow-up the 65 trial participants randomly assigned to receive the mobile closed-loop system spent significantly less time with blood glucose below 3.9 mmol/L (70 mg/dL) than the 62 assigned to receive a sensor-augmented pump (SAP), at averages of 2.4% versus 4.0%.
The trial also met its co-primary endpoint of noninferiority with respect to time with glucose levels above 10 mmol/L (180 mg/dL), with people in the closed-loop and SAP groups spending respective average times of 34% and 39% above this threshold.
The improvements with closed-loop control were most evident during sleep periods, with for example a significant 9.2% average increase in the time spent in target blood glucose range (between the two above thresholds) versus a nonsignificant 2.5% increase during awake periods.
All study participants had been using an insulin pump for at least 6 months prior to enrollment. The closed-loop system tested in this trial comprised an Accu-Chek Spirit Combo insulin pump and a Dexcom G4 or G5 continuous glucose monitor, controlled via Bluetooth by the inControl AP algorithm on an Android smartphone. People in the SAP group were also given Dexcom glucose monitors, which they used with their own pumps.
“Our results suggest that mobile closed-loop systems are likely to be viable options in the future, provided that system connectivity can be reliably achieved,” conclude the researchers.
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