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  • How safe are closed loop artificial pancreas systems?

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    For World Diabetes Day, Lotty Tizzard, Patient Safety Learning's Content and Engagement Manager, takes a look at the benefits of closed-loop insulin delivery, how patients have literally led on its development, and patient safety issues associated with artificial pancreas systems.


    What is closed-loop insulin delivery?

    ‘Closed-loop’ insulin delivery, also known as an artificial pancreas system (APS), is a self-regulating system for administering insulin to patients with type 1 diabetes.

    An insulin pump is connected to a continuous glucose monitor (CGM) via a smartphone app or minicomputer - in some systems, this is built into the insulin pump. The app or pump uses an algorithm to respond to blood glucose data from the CGM, automatically adjusting insulin delivery from the pump. The CGM then picks up resulting changes in blood glucose levels and relays this information back to the app, which will again adjust insulin delivery. This cycle is a ‘closed loop’, automatically adjusting insulin to keep blood glucose levels within a target range, without human input.


    A game-changer for diabetes care

    The system has major benefits for people living with type 1 diabetes.

    • Most users report drastic improvements to glycaemic control, both in HbA1c (a long-term measure of blood glucose) and blood glucose ‘time in target’.[1]
    • Closed-loop systems can alleviate the strain of constant decision making for people with diabetes and their families.[2] Traditional treatment with multiple daily injections or an insulin pump relies on the person with diabetes (or a carer) to constantly make decisions to try and keep blood glucose levels stable and safe. Awareness of the long- and short-term consequences of poor control [3] adds to the significant mental burden of living with type 1 diabetes.[4]
    • Using an APS can reduce safety fears for patients and their families. Hypoglycaemia (low blood sugar) caused by insulin treatment causes unpleasant symptoms and can lead to seizures, passing out and even death. It is a particular concern for parents of young children, as overnight hypos can be hard to detect and dangerous if left untreated. One parent of a toddler using an APS said the system means they can finally sleep without anxiety: “No worry if my child will be alive the next morning, not jumping out of bed due to a car alarm out on the street and thinking that it was the pump’s alarm, nothing; just sleep, for us and our child.”[5]

    There are currently three commercial hybrid closed-loop systems available in the UK - the Medtronic 670G/780G, Tandem t:slim X2 Control IQ and CamAPS FX systems [6] and the earliest has been available since 2019. Although the technology has huge benefits for people with diabetes, limited funding means that it is only available to a very small number of NHS patients.

    The DIY artificial pancreas and #WeAreNotWaiting 

    But there is another way to access closed-loop technology - by building your own artificial pancreas. Long before the first commercial closed-loop system was licensed for UK use, people with diabetes were writing their own algorithms and making them available to others within the diabetes community. Over the past six years, several patients and family members have developed code to allow anyone to build their own artificial pancreas. Known as ‘loopers’, this motivated group has developed an extensive range of open-source programmes, resources and training. There are an estimated 8-10,000 people worldwide using one of the three major open source algorithms, Loop, OpenAPS and AndroidAPS.[7]

    The hashtag ‘#WeAreNotWaiting’ was adopted on social media as patients began taking action to speed up the development of diabetes technologies. This patient movement uses Twitter and Facebook to share resources, issues and fixes with anyone who wants to build a DIY APS. Setting one up requires time, the right kit and a degree of technological ability, and an increasing number of people are doing it for themselves.

    Jazz Sethi, Founder of The Diabesties Foundation and the first known person in India to set up a DIY APS, says:

    I had heard of the DIY loop and the #WeAreNotWaiting movement a while back. Getting genuinely tired of fluctuating sugars, I decided to take the plunge. The process was not as difficult as I had anticipated - if you are a little tech-savvy, setting up the loop is just following instructions and using common sense. As soon as I started using the loop, I could see that it had increased my basal rate to correct my high sugar. It was... magic! My quality of life has seen a drastic improvement. Being in range 90-95% of the time has meant I’m not constantly exhausted from correcting for either a high or a low. My eating patterns have regulated now that I’m not snacking for lows and my anxiety and fear of hypos have reduced.

    DIY APS developers say that the DIY approach allows a more personalised experience for users, with their systems able to do more than commercial options thanks to years of customisation and constant development.[8] One recent research study even demonstrated that DIY systems provide better time-in-range outcomes than one of the commercially available systems.[9]

    What are the patient safety issues with closed-loop insulin delivery systems?

    There are many benefits to APS, but there are undoubtedly patient safety issues associated with their use:

    • Over-reliance on technology No technology is perfect and sometimes insulin pumps break and CGMs malfunction. Although technology can relieve the burden of diabetes care, patients should never discount the value of their own human instinct and input in the processes that keep them healthy. To mitigate this risk, DIY APS documentation contains clear and extensive warnings about the need to ensure people take responsibility for their own wellbeing while using the system, and patients using commercial systems must undergo training to ensure they understand their role.
    • Patients being ‘left behind’ Most people with type 1 diabetes are not able to access an APS, whether commercially-produced or DIY. It is expensive to self-fund a commercial APS, and building a DIY APS also involves substantial cost as it requires multiple tech components. Many patients cannot access funding for insulin pumps and CGMs [10] to use in a DIY system and the cost to buy these component devices is considerable. In addition, social media has helped a huge number of people access DIY APS programmes, but there are plenty of people with type 1 diabetes who have never even heard of looping. Considering the safety advantages of this technology for people with type 1 diabetes, there is still much work to do to ensure those who could most benefit are able to access it.

    There are also a few safety issues specifically related to open-source DIY APS:

    • Use of old technology Due to the cost of self-funding CGMs and insulin pumps, DIY APS users sometimes buy second-hand, out-of-warranty components from unregulated sources. There is a risk that these devices will be damaged or more susceptible to faults. Creating wider access to these technologies within the NHS would reduce this risk and allow a wider group of patients to try out DIY looping.
    • Lack of regulation While DIY closed loops have been shown to be safe and effective in improving outcomes, there is an extent to which users must accept the risks of using a DIY system. No regulatory body has yet approved their use.[11

      Organisations that monitor medical tech also urge caution when using apps to support diabetes management. Liz Ashall-Payne, CEO of ORCHA says, "Such systems highlight the life changing role technology can play in people's lives. But given its essential role, upholding safety standards is paramount. ORCHA continuously scans the market for smartphone apps that better manage living with diabetes, then rigorously assesses these products. We encourage anyone who is looking to develop or use such products, to make sure there is independent verification of safety standards."

      But as Tim Street, Founder of diabetes tech blog Diabettech highlights, “All of the open source options follow a rigorous development and testing process that is very similar to that undertaken by commercial offerings. The developers are all users or carers for users, so a safety first approach is taken and the testing is very controlled.” The personal investment that users have in these systems is an additional safety motivation that commercial biotech companies don’t have.
    • Liability issues If DIY looping goes wrong, there is a big question mark over who could be held liable,[12] with suggestions that programmers, distributors, loopers themselves and even NHS staff could be held responsible in legal terms. This creates a nervousness around looping that has caused some clinicians to avoid involvement with DIY APS. Partha Kar, NHS England’s National Specialty Advisor for Diabetes, recognises the significance of this issue: “Clinicians are worried about DIY systems as they aren’t sure whether the GMC would support them should something go wrong.

    A recent article in Medical Law International also highlighted that this problem is restricting access to DIY APS: “Practically speaking, this has led to clinicians adopting a precautionary approach in the clinic. Generally, even clinicians who are aware of the existence of DIY systems do not discuss them as an option unless the patient raises the issue themselves.”[11] The authors of this article call for clearer guidance for clinicians and highlight that “there is nothing in [the GMC guidance] which ought to be interpreted as requiring clinicians to refrain from discussing DIY APS with, or recommending them to, their patients.”[11]

    An international consensus paper on the issue of APS liability is in the pipeline and should help mitigate concerns and allow clinicians to feel more able to get involved in supporting patients using APS.[7]

    In spite of these issues, a number of research studies have now demonstrated the relative safety of DIY APS systems.[2][13][14] It is also important to consider safety issues related to looping within the context of wider safety issues faced by people with type 1 diabetes. As Dana Lewis, an early developer and champion of DIY APS puts it,

    “...a net risk safety perspective should be used, considering the almost constant risk of insulin management for people living with diabetes.”[15]

    The future of artificial pancreas technology

    So where will closed loop artificial pancreas systems go from here? As more and more people make use of DIY APS, the biotech industry is catching up. Several manufacturers have released closed-loop systems in the UK, but these are likely to be limited to a small number of NHS patients for several years, due to their cost. But progress is being made as the evidence around the benefits of APS is better understood, as Partha Kar outlines:

    We are working with NICE to assess how best to use commercial systems going forward and are currently collecting data to inform future guidance.

    The parallel development of ‘ultra-rapid acting insulins’ is likely to make closed-loop systems even more effective in managing blood glucose changes. Currently, most systems still require a level of input when it comes to taking insulin for meals, but ultra-rapid acting insulins may make closed-loop systems more effective in dealing with mealtime insulin delivery,[16] further relieving the burden of decisions for people with diabetes.

    The DIY APS is an inspiring example of how patients can lead progress in managing their condition. As Partha Kar highlights,

    The DIY movement has fast-tracked diabetes care by 5-10 years and forced industry to change their way of working - and that’s no mean feat. This group is highly motivated and has shaken the industry up - now every diabetes tech company is thinking about looping. Those companies that are working with DIY developers will benefit from their experience and knowledge as they develop their technology.” 

    The #WeAreNotWaiting movement has generated huge progress in diabetes treatment, but further research and guidance for clinicians is needed to ensure more people with diabetes can benefit. As a 2020 comprehensive review of the DIY APS states, “the lack of systematic practice-oriented studies is considered to be the stumbling block to the wider acknowledgement of DIYAP systems.”[17] But DIY loopers, researchers, clinicians and regulators are increasingly collaborating to see this issue overcome.

    Do you use a closed-loop artificial pancreas system? Have you made your own DIY APS? Share your experiences in the comments below.

    Further reading

    History and Perspective on DIY Closed Looping (Dana Lewis, OpenAPS)
    NHS Pilot: Patients with type 1 diabetes to get artificial pancreas on the NHS (NHS England)


    1 Fuchs J, Hovorka R, Smith L et al. Benefits and Challenges of Current Closed-Loop Technologies in Children and Young People With Type 1 DiabetesFront Pediatr. 2021:9
    2 Gawrecki A, Zozulinska-Ziolkiewicz D, Michalak M et al. Safety and glycemic outcomes of do-it-yourself AndroidAPS hybrid closed-loop system in adults with type 1 diabetesPLOS ONE. 2021:16(4)
    3 NHS type 1 diabetes - avoiding complications, accessed 8 November 2021
    4 Rustad J, Musselman D, Skyler J et al. Decision-Making in diabetes mellitus type 1J Neuropsychiatry Clin Neurosci. 2013:25:40-50
    5 Marshall D, Holloway M, Korer M et al. Do-It-Yourself Artificial Pancreas Systems in type 1 diabetes: Perspectives of two adult users, a caregiver and three physiciansDiabetes Therapy2019:10:1553–1564
    6 Leelarathna L, Choudhary P, Wilmot E et al. Hybrid Closed-loop therapy: Where are we in 2021? Diabetes Obes Metab. 2020
    7 Forthcoming consensus statement offers guidance on DIY closed-looping. Medicine Matters. 5 June 2021
    #WeAreNotWaiting - Using innovative, do-it-yourself hacks, healthcare consumers are creating solutions to help manage their diabetes. Genome Magazine 3 April 2018
    9 Jeyaventhan R, Gallen G, Choudhary P et al. A real-world study of user characteristics, safety and efficacy of open-source closed-loop systems and Medtronic 670GDiabetes Obes Metab. 2021:23(8):1989-1994
    10 NICE guidance: insulin pump therapy for diabetes accessed 8 November 2021
    11 Roberts J, Moore V, Quigley M. Prescribing unapproved medical devices? The case of DIY artificial pancreas systemsMedical Law International. 2021:21(1):42-68
    12 The DIY artificial pancreas: Who is liable if something goes wrong? University of Birmingham website. 28 May 2020
    13 Toffanin C, Kozak M, Sumnik Z et al. In Silico Trials of an Open-Source Android-Based Artificial Pancreas: A New Paradigm to Test Safety and Efficacy of Do-It-Yourself SystemsDiabetes technology & therapeutics2020:22(2):112-120
    14 Melmer A, Züger T, Lewis D et al. Glycaemic control in individuals with type 1 diabetes using an open source artificial pancreas systemDiabetes Obes Metab. 2019:21(10):2333-2337
    15 Lewis D. Errors of Commission or Omission: The Net Risk Safety Analysis Conversation We Should Be Having Around Automated Insulin Delivery Systems. Diabetic Medicine. 2021:9
    16 Lal R, Ekhlaspour L, Hood K et al. Realizing a Closed-Loop (Artificial Pancreas) System for the Treatment of Type 1 Diabetes. Endocrine Reviews. 2019:40(6):1521–1546
    17 Kesavadev J, Srinivasan S, Saboo B et al. The Do-It-Yourself Artificial Pancreas: A Comprehensive ReviewDiabetes Ther. 2020:11(6):1217-1235

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