ADA: Smart Phone Tracks Blood Sugar with Artificial Pancreas

The first wearable artificial pancreas platform based on a smart phone passes early feasibility tests….

Boris Kovatchev, PhD, of the University of Virginia in Charlottesville, stated that, "The investigational closed-loop system worked correctly 98% of the total possible time from admission to discharge, which exceeded the initially set primary endpoint goal of 80%."

Still, there is a way to go before the artificial pancreas is ready for clinical use. While the system worked correctly, blood glucose levels were only in the target range of 70 to 180 mg/dL about 80% of the time during the overnight hours.

Co-author Howard Zisser, MD, of the University of California Santa Barbara, added that, "A lot of the problem is that we need faster insulin, and the system still needs improvement. But we have come a long way; older sensors didn’t work correctly and would just shut down."

"From last year to this year, we have progressed so that we now have a good way to control overnight delivery of insulin from minute to minute, cutting down on episodes of hypoglycemia," he said.

Called the Diabetes Assistant, the system consists of a sensor placed under the skin that determines the interstitial glucose concentration, and transmits the information to a receiver. The information is processed and a signal is sent to the "brain" of the system, which tells the pump how much insulin to give.

The 20 patients with type 1 diabetes in the study didn’t just test the system in a hospital or clinic. Accompanied by researchers, they went on field trips and to restaurants, all while wearing the device.

A continuous glucose monitoring/pump system (Dexcom Seven Plus/Omnipod) was placed on each subject and was connected to a smart phone device. The patient operated the system via the Diabetes Assistant user interface in open-loop mode for the first 14 hours of study. Then, they switched to closed-loop monitoring for another 28 hours.

The researchers monitored patients remotely via 3G or WiFi connections to the diabetes assistant and were available on site for assistance.

"The graphical user interface proved to be reliable and well-understood by the subjects. All were able to easily navigate through commands on their own in both open-loop and closed-loop modes of operation, view continuous glucose monitoring and insulin information, and administer meal or correction boluses as needed," the researchers wrote.

Importantly, participants were free to move around. One subject used a hotel treadmill, one rode a bike, one walked to nearby museums, and five even took showers with the pouch hanging just outside of the shower.

The total duration of proper system communication functioning was 807.5 hours (274 hours in open-loop and 533.5 hours in closed-loop), which represented 97.7% of the total possible time from admission to discharge.

There were no serious adverse effects and no system failures. On six occasions, carbohydrate treatment was administered for blood glucose levels below 60 mg/dL, for a total of 0.17 events per 24 hours of operation.

Also, three patients developed mild ketosis, which was promptly and successfully treated with subcutaneous insulin.

"Combined with real-time remote monitoring, this system opens the possibility for large pivotal trials that establish the artificial pancreas as a viable mainstream treatment strategy in type 1 diabetes," the researchers wrote.

Practice Pearls:

• This study demonstrated that a smart phone is capable of running an outpatient closed-loop glucose control system with proper functioning 98% of the time.
• Note, however, that blood glucose levels were only in the target range of 70 to 180 mg/dL about 80% of the time during the overnight hours.
• This study was published as an abstract and presented at a conference. These data and conclusions should be considered to be preliminary until published in a peer-reviewed journal.

Kovatchev, B et al "Feasibility of outpatient fully integrated closed-loop control" Diab Care 2013; 36: 1851-1858.