By Nathan Seppa, Science News
A combination of high-tech glucose sensors, a computerized dosing calculator and a small insulin pump may someday allow people with type 1 diabetes to skip the routine injections and blood sugar checks that are a hallmark of the disease.
Armed with software that uses ongoing blood sugar readings to determine hormonal needs, researchers report initial success using an automated “closed loop system” that basically mimics the workings of a healthy pancreas, scientists report in the April 14 Science Translational Medicine.
“The technology exists right now for this closed loop system,” says study coauthor Steven Russell, an endocrinologist at Harvard Medical School and Massachusetts General Hospital in Boston.
The final product, still several years away, would consist of a pager-sized device not much bigger than the insulin pumps some diabetics wear today. The device would house dual pumps for both insulin, which lowers blood sugar, and its hormonal counterpart glucagon, which has the opposite effect. Another compartment would receive real-time glucose readings from a sensor under the skin and pass that information to a computer chip. The chip would control the pumps, adjusting the individual’s insulin and glucagon dosages as needed without the person ever lifting — or pricking — a finger.
Current insulin pumps store the hormone in small reservoirs on a belt and deliver the hormone via a small tube poked through the skin and taped in place.
In the new study, Russell and his colleagues show that the mathematical algorithm contained in the software worked in 11 people who had type 1 diabetes. The volunteers ate three high-carbohydrate meals over 27 hours under close observation while researchers obtained blood sugar readings every five minutes via standard intravenous catheters placed in each patient’s arm. Those readings went into a laptop computer, which calculated the proper amount of insulin and glucagon needed. A nurse used that readout to manually trigger the pumps to dose each patient. This rather cumbersome hardware array and a full-time staff were required for an initial safe test that the algorithm works, says study coauthor Edward Damiano, a biomedical engineer at Boston University. Six of the 11 patients stayed within the normal blood sugar range, with five showing some drops. After adjusting the algorithm to account for slower absorption of insulin in those five, a repeat test showed the technology prevented hypoglycemia and maintained blood sugar at a manageable level.
“Their findings suggest that the safe use of a bi-hormonal artificial endocrine pancreas to control blood glucose concentrations is possible,” say Larry Brown and Elazer Edelman of MIT, writing in the same Science Translational Medicine issue. Chronic high blood sugar can cause damage to the heart, kidneys and eyesight.
In addition to losing the vital beta cells that naturally make insulin, the pancreases of people with type 1 diabetes also fail to fine-tune glucagon production, Russell says. Brown and Edelman note that in the new tests, “Optimized algorithm-controlled infusion of glucagon with insulin enabled avoidance of hypoglycemia.”
Currently, patients with insulin pumps whose blood sugar has risen beyond the norm or who are about to eat a meal press a button to receive a dose of insulin. By eliminating manual dosing, the new technology avoids some of the vagaries of self-treatment, Damiano says. But in practice, there would be manual overrides with alarm beepers in case a mechanical failure by the automated system caused a sharp rise or fall in blood sugar, he says.
The research team plans further testing with more people over longer time periods and while exercising. Damiano estimates that a fully automated and exhaustively tested wearable version might be ready for regulatory approval in five years for insulin and seven years for a combination insulin and glucagon delivery system.