Hybrid closed loop (HCL) systems are delivering on clinical trial outcomes, with kids having better glycaemic control in real life while on- versus off-device, but best results may hinge on adequate support and education, Australian researchers say.

Their study of 71 children with type 1 diabetes (T1D) found patients had better glucose control and less fluctuations on HCL than off. They also had challenges with the technology, which led some to discontinue therapy.

To improve use and clinical outcomes, patients need ongoing support and education, potentially facilitated by HCL and T1D experts, family and healthcare professional resources and a combination of face-to-face and telehealth appointments, the authors from Perth Children’s Hospital and the University of Western Australia suggested.

Published in the Journal of Paediatrics and Child Health, their study reviewed clinical outcomes in kids (mean age 12 years) who had T1D, attended the Hospital between 2019 and 2021 and used the Medtronic 670G HCL, along with patient and family experiences.

It found the 52 patients assessed for glycaemic outcomes spent more time in target glucose range (TIR) (3.9–10 mmol/L) while on HCL than prior to, with mean %TIR increasing from 59.8% at baseline to 67.6% at three months and 65.6% at six.

It comes despite patients spending less time in the closed loop from four weeks to three and six months (78% to 69% [P = 0.037] and 63% [P = 0.001] respectively).

The magnitude of TIR improvement (mean adjusted difference of 7.8% points [P < 0.001] and 5.5% points [P = 0.009] at three and six months, respectively) “is similar to the 6.7% difference between HCL and standard therapy at the end of the six-month [randomised controlled trial] in Australian youth with T1D”, the paper read.

“A 5% increase in TIR equates to an additional 1 hour a day in target glucose range and is clinically significant; every 5% increase in TIR is associated with reduction in risk of retinopathy by 28% and of microalbuminuria by 18%,” it noted.

Although TIR increased, time in < 3.0 mmol/L to > 13.9 mmol/L stayed the same.

“This suggests Medtronic 670G HCL is effective in reducing mild hyperglycaemia but not the more pronounced hyperglycaemia, which more often than not, result from missed meal boluses,” the authors wrote.

Pluses and minuses

Regarding user experience, 32 of 38 patients and families surveyed reported better glucose control while on auto mode and more than half liked HCL for this reason — particularly since it reduced overnight glucose fluctuation.

However, an inability to follow children’s glucose levels in real-time, frequent alarms and closed loop exits and device-related sleep disruption, workload and impact on daily life made HCL less palatable for some patients and their families, leading five participants to discontinue therapy.

Overall, 10 patients stopped HCL during the study, the authors reported.

Newer systems such as the Medtronic 770G and 780G have addressed some of these issues, and discussions about appropriate calibration times, reasons for auto mode exit and the need for premeal boluses for optimal functioning would go a long way to helping. patients get the most of HCL, they suggested.

“While most of the review revolves around patient behaviour, due consideration should be given to factors that can be modified by the [healthcare professional (HCP)],” the authors wrote.

A structured program with a dedicated team of HCL and T1D experts, frequent upskilling on HCL technology via the CARES (calculate, adjust, revert, educate, sensor/share) paradigm, HCP and family resources, and face-to-face and telehealth appointments, implemented at the Hospital was “generally favourably received by families” and could be adapted to other clinics, they suggested.

“HCL therapy is associated with improved glycaemia; however, adequate support and education are required for best outcomes”, they concluded.