First Studies of Wearable Artificial Pancreas
First Studies of Wearable Artificial Pancreas
Technology advancements in the past year made possible the development of DiAs, wearable ambulatory artificial pancreas platforms using an off-the-shelf smart phone as a computational hub. Besides more user-friendly touch-screen interface and wireless connectivity, one easily quantifiable result of the transition from a laptop-based to a phone-based closed-loop control is a significant reduction in the system weight, which brings the system one important step closer to ambulatory use. Ultimately, this would lead to "closing the loop" with a portable minimally invasive system suitable for home use. Industry is currently transitioning CGMs and pumps to include wireless connectivity; thus, DiAs is only the first of many portable devices that will be capable of wireless data exchange and fully integrated closed-loop control.
At the time of this outpatient trial, the DexCom Seven Plus and the OmniPod Insulet pump had short-range wireless capability to communicate with an iDex research platform. Also, for the iDex to establish wireless communication with DiAs, an intermediary tablet (or a cell phone) needed to be connected to the iDex. Hence, there was short-range wireless communication from the patient (wearing a pod and sensor/transmitter) to a pouch containing the iDex and tablet (or cell phone), and long-range wireless communication between the pouch and the DiAs artificial pancreas platform. These intermediate devices are now being phased out; communication boxes are no longer necessary. Such a technology improvement was anticipated in our study; thus, we focused on the smart phone computing and user-interface capabilities of the DiAs, assuming that this would be the device that is here to stay.
Special emphasis should be placed on the fact that the subjects were operating the system by themselves most of the time. To the best of our knowledge, this is the first trial in which the subjects were responsible for the oversight of their closed-loop systems, a step that is critical for outpatient deployment of closed-loop control. Based on this feedback, we conclude that the form factor of DiAs as an artificial pancreas platform is appropriate for outpatient use. However, before long-term efficacy studies comparing outpatient artificial pancreas with sensor-augmented pump therapy can proceed, system wearability during daily living and the reliability of device communications must be ensured. Testing of the system at four different sites in three countries and in a variety of hotel and restaurant settings using one, two, or five systems concurrently provided an opportunity to challenge DiAs with multiple scenarios that are likely to be encountered in nonhospital and, ultimately, home settings.
In general, the technical performance of the DiAs system with overall operational time of 98% exceeded the set goal of 80%. In retrospect, this goal may have been conservative, but before this study it was generally unclear whether a smart phone can run closed-loop control, and there was no experience to guide the choice of this goal. The principal system components—sensor, DiAs, and insulin pump—were reasonably reliable, with 0.03, 0.09, and 0.12 malfunction events necessitating device replacement per 24 h, respectively. Occasional CGM data points were lost (8.1%), but this did not result in skipping control cycles or discontinuation of the study; by design, control to range would function during transient absence of CGM data because the controller intervenes only if risks for hypoglycemia or hyperglycemia are detected.
Finally, we must emphasize the utility of remote monitoring, which was available on site and at remote locations (i.e., studies in Europe or in California were observed from Virginia and vice versa in real time). This was a critical aspect for patient safety that allowed close supervision so that intervention could occur quickly if needed. Our system allowed monitoring concurrently multiple patients, a feature that was tested at Sansum with five patients simultaneously. This feature alone will allow acceleration of the number of subjects who could be studied at the same time, reducing staffing costs and making artificial pancreas research more efficient.
In summary, a wearable inexpensive closed-loop control platform (DiAs) was created and tested in early feasibility studies. Combined with real-time remote monitoring, this system opens the possibility for large pivotal trials that will establish the artificial pancreas as a viable mainstream treatment strategy in type 1 diabetes.
Conclusions
Technology advancements in the past year made possible the development of DiAs, wearable ambulatory artificial pancreas platforms using an off-the-shelf smart phone as a computational hub. Besides more user-friendly touch-screen interface and wireless connectivity, one easily quantifiable result of the transition from a laptop-based to a phone-based closed-loop control is a significant reduction in the system weight, which brings the system one important step closer to ambulatory use. Ultimately, this would lead to "closing the loop" with a portable minimally invasive system suitable for home use. Industry is currently transitioning CGMs and pumps to include wireless connectivity; thus, DiAs is only the first of many portable devices that will be capable of wireless data exchange and fully integrated closed-loop control.
At the time of this outpatient trial, the DexCom Seven Plus and the OmniPod Insulet pump had short-range wireless capability to communicate with an iDex research platform. Also, for the iDex to establish wireless communication with DiAs, an intermediary tablet (or a cell phone) needed to be connected to the iDex. Hence, there was short-range wireless communication from the patient (wearing a pod and sensor/transmitter) to a pouch containing the iDex and tablet (or cell phone), and long-range wireless communication between the pouch and the DiAs artificial pancreas platform. These intermediate devices are now being phased out; communication boxes are no longer necessary. Such a technology improvement was anticipated in our study; thus, we focused on the smart phone computing and user-interface capabilities of the DiAs, assuming that this would be the device that is here to stay.
Special emphasis should be placed on the fact that the subjects were operating the system by themselves most of the time. To the best of our knowledge, this is the first trial in which the subjects were responsible for the oversight of their closed-loop systems, a step that is critical for outpatient deployment of closed-loop control. Based on this feedback, we conclude that the form factor of DiAs as an artificial pancreas platform is appropriate for outpatient use. However, before long-term efficacy studies comparing outpatient artificial pancreas with sensor-augmented pump therapy can proceed, system wearability during daily living and the reliability of device communications must be ensured. Testing of the system at four different sites in three countries and in a variety of hotel and restaurant settings using one, two, or five systems concurrently provided an opportunity to challenge DiAs with multiple scenarios that are likely to be encountered in nonhospital and, ultimately, home settings.
In general, the technical performance of the DiAs system with overall operational time of 98% exceeded the set goal of 80%. In retrospect, this goal may have been conservative, but before this study it was generally unclear whether a smart phone can run closed-loop control, and there was no experience to guide the choice of this goal. The principal system components—sensor, DiAs, and insulin pump—were reasonably reliable, with 0.03, 0.09, and 0.12 malfunction events necessitating device replacement per 24 h, respectively. Occasional CGM data points were lost (8.1%), but this did not result in skipping control cycles or discontinuation of the study; by design, control to range would function during transient absence of CGM data because the controller intervenes only if risks for hypoglycemia or hyperglycemia are detected.
Finally, we must emphasize the utility of remote monitoring, which was available on site and at remote locations (i.e., studies in Europe or in California were observed from Virginia and vice versa in real time). This was a critical aspect for patient safety that allowed close supervision so that intervention could occur quickly if needed. Our system allowed monitoring concurrently multiple patients, a feature that was tested at Sansum with five patients simultaneously. This feature alone will allow acceleration of the number of subjects who could be studied at the same time, reducing staffing costs and making artificial pancreas research more efficient.
In summary, a wearable inexpensive closed-loop control platform (DiAs) was created and tested in early feasibility studies. Combined with real-time remote monitoring, this system opens the possibility for large pivotal trials that will establish the artificial pancreas as a viable mainstream treatment strategy in type 1 diabetes.
