This story is from the category Augmenting Organics
Date posted: 16/06/2014
The latest version of a pancreas device has been successfully tested in two five-day clinical trials one in adults, the other in adolescents that imposed minimal restrictions on patient activities. A team of investigators from Boston University (BU) and Massachusetts General Hospital (MGH) report study results in a New England Journal of Medicine paper being issued online to coincide with a presentation (abstract # 237-OR) at the American Diabetes Association Scientific Sessions. The device controls blood sugar in patients with type 1 diabetes using doses of both insulin and the blood-sugar-raising hormone glucagon.
"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," says Edward Damiano, PhD, of the BU Department of Biomedical Engineering, principal investigator of the project and senior author of the NEJM report. "There's no current standard-of-care therapy that could match the results we saw."
Firas El-Khatib, PhD, of the BU Department of Biomedical Engineering, adds, "One of the key virtues of this device is its ability to start controlling the blood sugar instantly, based only on the patient's weight, and continually adapt its decision making regarding insulin and glucagon dosing to handle a wide range of dosing requirements." El-Khatib co-designed the bionic pancreas device with Damiano and is co-lead author of the NEJM report with Steven Russell, MD, PhD, of the MGH Diabetes Unit,.
Russell who led the clinical trials reported in the current paper Damiano, and El-Khatib previously published a 2010 Science Translational Medicine report that described successful use of the first-generation system in controlling the blood sugar of adults for 27 hours. But that study took place in a controlled hospital inpatient environment where participants essentially stayed in bed for the whole period and ate prescribed meals. "The key element with the current version of this device is that it's wearable, allowing participants to stay in something close to their usual environments, exercise and eat whatever they want," says Russell.
Additional inpatient trials conducted after the 2010 paper extended the study period to two days and included adolescents as well as adults. But developing a device that could be tested safely in an outpatient environment presented several challenges, first among which was a control system that could adapt not only to the minute-by-minute changing needs of an individual, but also to the very different needs of adults and adolescents. The rapid growth and hormonal changes of adolescence produces insulin requirements that are two to three times greater than those of adults of the same body weight, Damiano explains. And even though the dosage needs of adults are more predictable, contracting typical a illness like a cold or upset stomach can dramatically change the need for insulin over a period of days to weeks.
Along with the software improvements that allow the device to adapt to widely varied individual dosage needs, the new version also relies on improved hardware, including a smartphone (iPhone 4S) capable of practical wireless communication with two pumps delivering doses of insulin and glucagon. Every five minutes the smartphone receives a blood sugar reading from an attached continuous glucose monitor, which it uses to calculate and administer a dose of either insulin or glucagon. The smartphone includes an application on which the patient enters information immediately before eating. But instead of the complex calculation patients typically do to estimate their carbohydrate intake, this app only asks whether the meal consumed will be breakfast, lunch, or dinner and whether the carbohydrate content will be typical, larger or smaller than usual.
Both of the studies reported in the NEJM paper compared data reflecting five days on the bionic pancreas system with five days of participants' usual care using their own insulin pumps. The adult trial enrolled 20 participants who lived at home and managed their own care during the usual-care period. While on the bionic pancreas, participants needed to stay within a three-square-mile area of downtown Boston, which enabled constant wireless monitoring of the blood sugar levels by study staff. They were accompanied by a study nurse 24 hours a day and slept in a hotel; but were otherwise free to do as they chose, including exercising at a gym and eating in restaurants.
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