Commentary by: Edward Damiano, PhD
Researchers are making progress in developing a system that mimics the actions of a human pancreas to better help people with type 1 diabetes control their blood sugar levels. A current version of the system continuously monitors blood sugar levels and controls these levels using doses of both insulin and the blood-sugar-raising hormone glucagon.
How the Bionic Pancreas System Works
A smartphone receives blood sugar level readings every 5 minutes from a continuous glucose monitor worn on the abdomen (Figure 1). If blood sugar levels are too high, the smartphone signals a pump that gives a dose of insulin, and if blood sugar levels are too low, a signal is sent to a pump that gives a dose of glucagon. This mimics what usually happens in the body of someone who does not have diabetes.
Before eating, users enter which meal that they are about to eat (breakfast, lunch, or dinner) and whether the carbohydrate content will be typical, larger, or smaller than usual (Figure 2). If a user has low blood sugar, an alert is sent on the smartphone to tell the person to eat carbohydrates.
The bionic pancreas was tested in two 5-day trials—1 in 20 adults and 1 in 32 adolescents. The participants in each study were wirelessly monitored by study staff, but could eat and exercise as they liked.
The average blood glucose levels decreased significantly in both adults and adolescents when using the bionic pancreas compared to a control period during which the participants used their own insulin pumps. In adults, there were fewer cases of hypoglycemia (low blood sugar) when using the bionic pancreas than when not.
“In both of these studies, this device far exceeded our expectations in terms of its ability to regulate glucose, prevent hypoglycemia and automatically adapt to the very different needs of adults—some of whom were very insulin-sensitive—and adolescents, who typically need higher insulin doses,” said codeveloper of the system Edward Damiano, PhD, Associate Professor of Biomedical Engineering at Boston University. “There’s no current standard-of-care therapy that could match the results we saw,” he said.
Dr. Damiano, whose son was diagnosed with type 1 diabetes at the age of 11 months, explained what having a device like this could mean to people with this disease. “The most practical difference would be not having to think about diabetes 24/7, not having to constantly make decisions about things that those of us without type 1 never have to think about,” Dr. Damiano said. “Another real problem that would be relieved is the fear—fear of going to bed at night and not knowing if your blood sugar level will drop dangerously low while you sleep. Even our study participants, who controlled their blood sugars significantly better than national averages on their usual care, ran high levels overnight but still had significant episodes of hypoglycemia,” Dr. Damiano said.
“And another extremely frustrating aspect of diabetes that would be completely eliminated by this device is the enormous sense of failure when you stare at that glucose meter and, despite everything you do to control it; your blood sugar is not in or near the normal range,” Dr. Damiano said. “But of course you didn’t fail; the tools that are available to you failed. The bionic pancreas we are working toward would relieve that sense of failure and provide a bridge to the often-promised but still elusive cure for type 1 diabetes,” he noted.
1. Massachusetts General Hospital. News release: Bionic pancreas successfully controls blood sugar levels in adults, adolescents with type 1 diabetes. June 15, 2014. http://www.massgeneral.org/about/pressrelease.aspx?id=1715. Accessed May 4, 2015.
Russell SJ, El-Khatib FH, Sinha M, et al. Outpatient glycemic control with a bionic pancreas in type 1 diabetes. N Engl J Med. 2014;371(4):313-325.