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The daily burden of managing type 1 diabetes (T1D) is a significant challenge, but often it's not the most worrisome concern brought on by the disease. For many people with T1D, that distinction goes to the anxiety they feel at bedtime, because life-threatening low blood-sugar episodes are most likely to occur and remain unaddressed during sleep.
In 2006, researchers around the globe came together to turn a concept known as the artificial pancreas (AP) into an actual system that would automatically keep blood glucose within a tightly controlled range, relieving the burden of managing T1D and substantially reducing the risk of deadly low blood-sugar episodes and diabetic complications later in life.
The AP Project Consortium, which was launched and continues to receive support from the Juvenile Diabetes Research Foundation, brings together medical researchers, engineers, mathematicians, and industry to share information, ideas, and resources for developing effective and reliable AP systems. These systems approximate the operation of a normal human pancreas by combining a continuous glucose monitor (CGM) and insulin pump with an algorithm that anticipates blood-sugar levels, and automates delivery of the appropriate amount of insulin and, potentially, other key hormones.
With support from the AP Consortium, my colleagues and I at the University of Virginia in Charlottesville have been working for nearly a decade to develop a control-to-range system that we call the Diabetes Assistant (DiAs).
This system features an algorithm that can predict when blood-sugar levels will drop or increase and, in response, send a start or stop command to the insulin pump so that blood-glucose levels remain within a tight range. Users would still need to follow their routine mealtime bolus therapy, but otherwise the control-to-range system will provide fully automated delivery of insulin in response to the body's needs.
We have been testing DiAs through a variety of human clinical trials in diverse T1D populations over the past several years, and we have seen promising results.
In two initial pilot studies, participants stayed in hotels near the four study centers and went about their daily lives while wearing DiAs. In both studies, the volunteers experienced significant reductions in low blood-sugar episodes, particularly overnight. In fact, the episodes were nearly eliminated, and avoidance of low blood sugar didn't come at the risk of more high blood-sugar episodes.
Those two early pilots led to two extended outpatient studies where participants wear their AP systems around-the-clock, and live at home with them for several weeks at a time for a total of 6 months. DiAs trials to date have enrolled a combined total of 300 participants.
While preliminary data from the most recent trials won't be available until June, a meta-analysis of all of our studies to date was presented at a recent medical conference, and it showed that volunteers who used the system overnight experienced a two-thirds reduction in time spent in hypoglycemic states. Average blood-glucose levels also improved, and overnight time in the target blood-sugar range (70-180 mg/dL) increased to 78% from 64%.
The data for continuous 24-hour use showed the amount of time spent in a hypoglycemic range was reduced by more than half, and time spent in the target range rose to 73% from 66%. Average blood-glucose levels dropped slightly to 148 mg/dl from 154 mg/dL during 24-hour use of the closed-loop system.
Our goal is for these preliminary trials to form the basis for industry decisions to move towards commercialization of the first control-to-range AP systems. We also want to provide data that supports regulatory approval of these systems once they are ready for FDA review.
One of the most beneficial aspects of our clinical trial designs is that they have included a variety of age groups, including teens. Young people have different metabolic needs than adults, so including this demographic in our studies will help provide accurate insight into how these systems will function for them.
Boris Kovatchev, PhD, is director of the University of Virginia Center for Diabetes Technology.