Evaluation of an Interoperable Artificial Pancreas System (iAPS)

An interoperable artificial pancreas system smartphone app was designed, developed, and tested to make decision-making algorithms while running on an unlocked smartphone. 

An Artificial Pancreas system closes the loop between a continuous glucose monitor (CGM) and an insulin pump by creating an algorithm that adjusts the insulin dose to control blood glucose in patients with type 1 diabetes. Recent studies demonstrate that an Artificial Pancreas improves outcomes over sensor-augmented pumps with specific improvements in target glucose range, less hypo- and hyperglycemia, and in longer–term studies, improved hemoglobin A1c.  

Due to current limitations, the Artificial Pancreases available today, commonly referred to as hybrid closed-loop systems, still require the patient to manually alter system functions in specific scenarios such as meal announcements. Fortunately, however, there are rapid advancements in these closed-loop systems, and many are being developed and tested in clinical settings.  

This article will focus on designing and evaluating a novel smartphone-based approach called the interoperable artificial pancreas system (iAPS). There were two main design goals: “seamless integration with leading CGM and insulin pump devices, and interface with different decision-making algorithms with an app running on an unlocked smartphone.”  

As mentioned, the development of hybrid closed-loop Artificial Pancreas systems is accelerating. In the United States in 2017, Medtronic released the MiniMed 670G for commercial sale. Other examples of hybrid closed-loop Artificial Pancreas systems that have been evaluated include Insulet’s OmniPod Horizon hybrid closed-loop system and inControl TypeZero technologies based in Charlottesville, VA, which have an Artificial Pancreas system based on a locked smartphone. There are many other companies and academic groups which are pursuing Artificial Pancreas systems.  

Specific features of the interoperable artificial pancreas system (iAPS) include: 

Device integration: wireless integration with Dexcom G5 and G6 CGM, two different insulin pumps. These insulin pumps (Tandem t:slim™ insulin pump and OmniPod® insulin pump with a modified Personal Diabetes Manager) have been limited to allow for Bluetooth Low Energy (BLE) communication with a smartphone.  

User Experience: iAPS intuitive user interface permits the user to interact with devices, to request an insulin bolus for correction or a meal, and many other activities.  
Other features include alarms and safeguards, along with remote monitoring.  

Once the app starts up, the user must verify an active registration record. Once verified, the app continuously completes a time-triggered control cycle comprised of:  

1. Confirming the selected pump is operational and requesting a temporary basal rate of 0U/h for 30 minutes;
2. Calculating a micro insulin bolus by communicating with the Closed Loop Controller;
3. Requesting delivery of the calculated bolus by the selected pump. This action is canceled if the user has requested a bolus and the pump is already delivering it;
4. Updating the Insulin On Board by communicating with the IOB module.  

There are also various user notifications that the app will present to the user, classified by severity and potential impact. In order of increasing severity:  

1. Notice: notification to update the user about decreased app performance due to a needed recalibration or loss of an internet connection;
2. Alert: notification to inform the user that the insulin pump cartridge is low, or of a loss of connection to the pump or Continuous Glucose Monitor; 
3. Alarm: notification that necessitates immediate action by the user as there is a danger of hypoglycemia, loss of BLE connection, or a scenario in which a bolus is not delivered. Another useful feature is that the user’s followers can be notified by text message when such an action needs to be taken.  

This particular closed-loop platform is suitable for use in clinical trials due to the specific advantages offered by this system. The iAPS app can work on many smartphones. The app itself is readily available through the Google Play store. The system is compatible with multiple insulin pumps and Continuous Glucose Monitors. 

Certain limitations of this system’s evaluation included the short duration of the trial, the small sample size, the 24-hour clinical supervision, and the technical support required. Future trials will emphasize further refinement of the system and applicability in real-life outpatient environments.  

Practice Pearls: 

• There is a demand for clinical trials of modular artificial pancreas systems.  
• The iAPS system achieved reliable connectivity with peripheral devices, thus limiting the need for user intervention. 
• The iAPS system regulated glucose levels safely and effectively, even under challenging conditions, and is suitable for use in outpatient environments.  

Deshpande, Sunil, et al. “Design and Clinical Evaluation of the Interoperable Artificial Pancreas System (IAPS) Smartphone App: Interoperable Components with Modular Design for Progressive Artificial Pancreas Research and Development” 

Mit Suthar, PharmD. Candidate, LECOM School of Pharmacy