medwireNews: The Cambridge closed-loop insulin delivery system significantly improves glycemic control during 6 months of use by children and adolescents compared with standard insulin pump therapy, report the DAN05 investigators.
The results also uncovered a large difference in usage time between the two systems used in the trial, with consequent differences in glycemic control.
The trial was run across multiple centers in the UK and the USA. Participants at the UK sites used the CamAPS FX system, which comprises the Dexcom G6 glucose sensor, the Dana Diabecare RS insulin pump, and the Cambridge control algorithm on an unlocked Android smartphone. Use of this system was high, at a median of over 90% for the entire 6-month period, ranging from approximately 80% to 98%.
Because the Dana Diabecare RS pump is not approved for use by the US regulatory authorities, US participants used the older FlorenceM system, consisting of the Medtronic MiniMed Guardian 3 glucose sensor and 640G insulin pump, with the Cambridge algorithm running on a locked Android smartphone. Use of this system was much lower, at approximately 55% in the first month, reducing to around 40% by month 6.
Presenting the results at the virtual ADA 81st Scientific Sessions, Julia Fuchs (University of Cambridge, UK) attributed this low usage to the need to calibrate the glucose sensor and the poor reliability of the system components. Two study participants randomly assigned to the closed-loop group withdrew due to device issues; both were using the FlorenceM system.
The 133 trial participants were aged between 6 and 18 years, with around 45% being 6–12 years of age, and their average baseline glycated hemoglobin (HbA1c) was 8.2–8.3% (66–67 mmol/mol). All were using an insulin pump and around two-thirds also used a continuous glucose monitor.
Fuchs reminded attendees of the low rates of target HbA1c attainment in children and adolescents, saying: “It’s clear that we need new solutions to support this at-risk population.”
After 6 months in the study there was a statistically significant but moderate difference in HbA1c levels between closed-loop control and continuation of standard insulin pump therapy, as well as a small increase in time in range, and no difference in fasting blood glucose.
But because of the divergent usage of the two systems, the team opted to analyze them separately. This revealed that use of the FlorenceM system had not resulted in improved glucose control.
By contrast, there was a “highly clinically significant treatment effect in the CamAPS FX cohort, which used reliable components and a factory-calibrated glucose sensor,” said Fuchs.
The children and adolescents using this system had a significant 1.05 percentage point (11.5 mmol/mol) reduction in HbA1c compared with the control group, as well as a 15 percentage point improvement in time in range, driven by a large reduction in the time spent in hyperglycemia, and a significant 1.98 mmol/L (35.74 mg/dL) decrease in average blood glucose level.
“This implies that closed-loop efficacy depends on automode usage,” said Fuchs.
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