Over One Third of Type 1 Diabetes Patients Quit Closed-Loop System

March 23, 2019

UPDATED WITH COMMENTARY March 25, 2019 // NEW ORLEANS — Among first-time users of the MiniMed 670G hybrid closed-loop insulin delivery system (Medtronic), almost 40% stopped using the device within 9 months, primarily because of technical difficulties, shows new research presented here at ENDO 2019: The Endocrine Society Annual Meeting.

Closed-loop insulin pump therapy is the most advanced technology available to date for type 1 diabetes. It's "theoretically brilliant, and it's the future," said co-lead investigator Gregory Goodwin, MD, of Boston Children's Hospital, Massachusetts, but "we need better systems," he told a press briefing here.

"For this to be available and practical for the average type 1 diabetes patient, we need more user-friendly technology," he said. "Anyone who takes care of patients knows that to be the case," he added.

The author of a previous study that looked at this issue, Gregory P. Forlenza, MD, assistant professor of pediatrics at the Barbara Davis Center for Diabetes, Aurora, Colorado, likened the MiniMed 670G to "a 1990s cell phone," telling Medscape Medical News last year, "It's not an iPhone 6.0. It's a giant leap forward in automation of insulin delivery, but it's not a plug-and-play system."

Anders L. Carlson, MD, medical director of the International Diabetes Center, Minneapolis, Minnesota, agreed.

"Automated insulin delivery is the future," he told assembled journalists here at ENDO 2019, "but the sensors need to get better."

And he noted that the technology is not the only barrier.

Although registry data on US patients with type 1 diabetes indicate insulin pumps and continuous glucose monitors (CGMs, also referred to as 'sensors') — the component parts of the closed-loop systems — are increasingly being used in the United States, still only about half of patients are engaging with this technology, Carlson noted.

"There's a chance we could leave some folks behind if we don't address issues such as socioeconomic," disparities and other related concerns, he said.

Why Are Patients Not Sticking With the System? "It's a Full-Time Job"

Goodwin explained that he and his colleagues "wanted to see how the MiniMed 670G works in the real world."

In hybrid closed-loop systems, there is algorithm-based communication between the insulin pump and CGM, and the basal insulin delivery is automated to minimize both low and high blood glucose readings, but the patient must still enter information about carbohydrate consumption.

The first such system to be marketed, the MiniMed 670G, was approved by the US Food and Drug Administration in 2016 for use in patients aged 14 years and older. In June 2018, this was expanded to include those aged 7 years and older.

Patients are eligible for the MiniMed 670G if they have experience using an insulin pump and CGM, express a preference for the device, and have the approval of their treating endocrinologist or nurse educator, Goodwin explained.

From May 2017 to August 2018, his clinic had 93 patients who elected to start treatment with the MiniMed 670G ranging in age from 5 to 25 years, with an average user age of 17 years. (Goodwin said that although the device is only approved for those aged 7 years and older, at his institution they do use it, at the discretion of the treating clinician, in those aged 5 years and older).

Of the 93 patients, 35 (38%) stopped using the MiniMed 670G within an average of 9 months of starting the device, which is "some of the longest follow-up data" to date of people on this system, said Goodwin.

Reasons for stopping use included frequent alarms, forced exits from automode so users have to switch back to manual mode, calibration requirements, premature sensor failure, skin adhesion problems, and sensor supply problems, he noted.

But overall, the majority of patients withdrew because "they were kicked out of automode," Goodwin said, explaining that "if you don't fulfill certain requirements, the system kicks you out."

"Most of the patients who withdrew, withdrew completely," he said.

"It's a full-time job, just to keep yourself in target."

Of the patients who continued to use the MiniMed 670G (62% of patients), those who managed to remain in automode more than 57% of the time saw significant reductions in HbA1c, he noted.

Goodwin concluded that to improve compliance with these devices and "improve success," manufacturers need to "decrease the frequency of alarms, and decrease the frequency of forced exit from automode."

"This was the first generation of the system. It will improve with time," he added.

A Medtronic spokesperson told Medscape Medical News: “We have made enhancements to the system since this study was done which would likely mitigate many of the issues experienced. Specifically, we updated the software in the transmitter that sends sensor information to the insulin pump.

"When the MiniMed 670G system was initially launched 2 years ago, it included an additional layer of protection which, in certain instances, can create a continuous request for blood glucose entries. To improve the patient experience, we created a software enhancement that removes the additional safety check without compromising patient safety. All MiniMed 670G systems shipping today have this enhanced transmitter, and we are replacing the transmitter for anyone experiencing an issue."

Goodwin also told Medscape Medical News that there's lots of interest from companies in developing hybrid closed-loop systems using the Dexcom G6 sensor, which was approved in the United States last year.

ENDO 2019. Presented March 24, 2019. Abstract OR14-5.

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