Adaptive and flexible: Closed-loop technology for all
Guiding Roman Hovorka’s algorithm towards the Android store
When discussing the current state of play in the artificial pancreas field, the JDRF’s Dan Finan described Roman Hovorka (University of Cambridge, UK) as a “visionary” and said that some people see his closed-loop insulin delivery algorithm as “the best algorithm out there.”
Hovorka himself tells medwireNews that “based on existing data our algorithm is currently the best – or arguably the best – based on randomized clinical trials of at least 3 months’ duration.”
He puts this down to two aspects. One is that they “are trying to provide a reasonable amount of freedom for the users to be able to modify the behavior” of the algorithm – when they are exercising, for example, or by changing the target glucose levels to allow for personal preference or situations such as pregnancy.
“These additional features which interact with the user are at least as good as any other algorithm has and I think in many aspects are exceeding other algorithms,” he says.
But Hovorka believes the “distinguishing feature” of his team’s algorithm is its ability to adapt to the individual user. It can “respond to the changing needs – insulin needs – from day to day to a greater extent than other algorithms,” he says. “So it is the adaptive component which I think is providing our algorithm substantial benefits.”
Hovorka is keenly aware that different subgroups of users with type 1 diabetes have different needs in terms of glucose control as well as how they interact with a closed-loop system and the benefits they receive from it – hence the heavy emphasis on an adaptive and interactive system.
In addition to improved glucose control, “there are also psychosocial benefits, which means people can have more sleep, they have more time doing things – they can feel that they have time off diabetes,” says Hovorka. “And I think these psychosocial benefits are really different for different populations.”
For example, the team recently reported that children aged 6 years or younger have greater variability in their daily insulin needs than older children or adults, as a result of which Hovorka particularly recommends closed-loop insulin delivery for this age group. But another major consideration for younger children is that family members, carers, and school teachers have to be able to interact with and understand the system, and Hovorka stresses that “giving the parents time to have normal lives is so important for the family,” to reduce family disease-related stress.
In teenagers, who “don't really look after themselves,” a closed-loop system can act as a damage limiter for missed pre-meal boluses, whereas for adults the tool may “allow them to have a greater engagement and feeling of ownership of the treatment and management” of their diabetes.
The awareness of this wide range of needs is reflected in Hovorka’s approach to the clinical testing of his closed-loop system. His team’s research to date has included people of all ages with poorly controlled diabetes, people with well-controlled diabetes, very young children, and pregnant women.
In addition, the team has tested a modified version of the algorithm in inpatients with type 2 diabetes, including those requiring nutritional support. Hovorka believes that the idea of automated control of glucose levels in hospitalized patients “will become more and more important over the next decade or two, especially in the US and probably later on in Europe.”
And their research across the full range of potential artificial pancreas users continues. “So now we are really busy,” says Hovorka.
He lists five current studies in different user groups: a 6-month trial in 230 participants; a study in children aged 2–7 years across four countries; a 4-year study in adolescents aged 10–16 years newly diagnosed with diabetes; a 4-month trial in people aged 60 years or older; and a study of patients on dialysis, using the inpatient algorithm. An additional study is comparing insulin aspart with faster insulin aspart within a closed-loop system.
All these studies are providing data to support the anticipated approval of Hovorka’s closed-loop algorithm for use by people with type 1 diabetes in the real world.
“So we are looking at commercializing maybe towards the end of this year,” he says. “It's basically an app on a phone – Android phone – initially talking to just one pump and one sensor, but the plan would be to expand on that.”
This means that, similar to the intended commercialization of the open-source Loop algorithm, users will ultimately have multiple closed-loop system components they can use with a single control algorithm, increasing user choice and, hopefully, persistence with the system.
Hovorka highlights recent data showing a high rate of drop-off among users of what is currently the only commercially available artificial pancreas system – the Medtronic 670G. Half of the initial 84 users had stopped using the system in closed-loop mode after 1 year of use, citing issues including glucose sensor problems and the high frequency of system alarms.
The Medtronic system is “designed for safety, which means tremendous burden at times for users, and it just burns them out,” says Hovorka.
The company is in fact now trialing an upgraded system that aims to address some of these issues.
Hovorka’s longer-term research goals lie in a similar vein to his current studies, focusing for the most part on inpatient care and widening the spectrum of people with type 1 diabetes who are proven to benefit from closed-loop insulin delivery.
But he also highlights the need to improve glucose control when users eat. “The mealtime is the challenging bit,” he notes.
The ultimate aim, of course, is to entirely avoid the need for mealtime insulin boluses. “I think that’s the next big goal in this field,” says Hovorka, but adds: “I think it’s really difficult to see with the existing configuration” of closed-loop delivery systems.
Other tools that might help achieve this goal include dual- or triple-hormone systems using drugs such as pramlintide, which slows glucose absorption. But these would be expensive solutions. There are also faster-acting insulins available and in development, and the possibility to use inhaled rather than injected insulin.
But Hovorka does not anticipate a solution being available in the near future. “People are thinking about it,” he says, “but I can’t see any easy way with the existing tools which are available to really make it happen in the way which would not [compromise] glucose control.”
medwireNews is an independent medical news service provided by Springer Healthcare. © 2019 Springer Healthcare part of the Springer Nature group