Closed loop insulin delivery systems: an update

Closed loop insulin delivery systems: an update

What is closed loop insulin delivery?

Closed loop insulin delivery, also referred as “artificial pancreas”, is a system that tries to mimic what the human pancreas is meant to do by using real time continuous glucose monitor data to automatically adjust the insulin pump’s basal insulin delivery.  It is not completely automated as, depending on the model, the user needs to manage insulin boluses at mealtime.

It is expected to be able to deliver insulin in a glucose-responsive fashion thus providing improved glycemic control, more time in target, and reduced burden and frequency of hypoglycemia.

The concept has been around since early 2000s with many companies are working on bringing their own versions to the market in addition to the many DIY versions that have been developed by the users themselves.  

Results from clinical studies have shown safety and blood sugar management benefit, however there still is a need for better performance and acceptability. (1)

 Use in young children?

While the use of closed loop systems in adults has been tested in at-home and unsupervised settings and supported by many studies, its performance in young children was limited to controlled settings. A new study published in 2019 evaluated the safety and feasibility of using closed-loop insulin delivery systems in home settings in children with type 1 diabetes aged 1–7 years.

After testing the closed-loop systems for two 21-day periods (a total of 6 weeks) in 24 children the authors found that the system was safe and didn’t increase the risk of severe hypoglycemia or keto-acidosis. Due to the lack of a control group (a group who wouldn’t be on an intervention) to compare to the standard practice, the researchers couldn’t evaluate if closed-loop systems were able to improve glucose control or reduce risk of hypoglycemia more than traditional treatment which warrants further investigation. (2)

User friendly for some but not for all

Some recently presented results at the 2019 Endocrine Society annual meeting in New Orleans, reported that technical difficulties with the sensor and or difficulties with staying in automated closed loop delivery mode were the most common reason why about 20% of the patients on a closed loop system (in this instance the Medtronic 670G) elected to discontinue use completely.

Other issues that also presented a challenge to many users included calibration requirements, problems with sensor durability or adhesion, skin irritation and forced exits from auto-mode. Researchers also noticed that among those who remained on the closed loop system, the time in automatic mode varied widely between 10 to 90% of the time, with those staying in automatic mode longer having better glycated hemoglobin A1c results. However, patients who continued to use auto-mode technology had an average decrease in hemoglobin A1c of 0.27% after an average of 97 days use. (3)

While the technology seems to be still challenging for a large portion of potential users, it is important to note that the technology will continue to improve and that users’ feedback and patient experience-centered research will help in the development of friendlier user interface and better adapted systems.

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 References: 

  1. Waseem Majeed & Hood Thabit (2018) Closed-loop insulin delivery: current status of diabetes technologies and future prospects, Expert Review of Medical Devices, 15:8, 579-590, DOI: 10.1080/17434440.2018.1503530
  2. Tauschmann, M., Allen, J., Nagl, K., Fritsch, M., Yong, J., Metcalfe, E., . . . KidsAP Consortium. (2019). Home use of day-and-night hybrid closed-loop insulin delivery in very young children: A multicenter, 3-week, randomized trial. Diabetes Care, 42(4), 594-600. doi:10.2337/dc18-1881
  3. Goodwin G, et al “Challenges in Implementing Hybrid Closed Loop Insulin Pump Therapy (Medtronic 670g) in a ‘Real-World’ Clinical Setting” ENDO 2019; Abstract OR14-5.