Artificial Pancreas Works While Patients Sleep, Yale Study Shows

A computer-controlled device designed to mimic the human pancreas by sensing and regulating glucose controlled the blood sugar of Type 1 diabetics at night better than a traditional insulin pump, a study showed.

The study of 12 people showed that 86 percent of patients using the so-called artificial pancreas had blood sugar at recommended levels at night, according to researchers at Yale University in New Haven, Connecticut. When the same 12 people used the insulin pumps requiring them to get up and activate the equipment, the percentage of patients achieving recommended blood sugar levels dropped to 52 percent. The data will be presented tomorrow at the American Diabetes Association annual meeting in San Diego.

The findings are leading researchers closer to the goal of creating a device that can act like the pancreas, which senses when the body needs insulin and delivers it without a person being aware, said Stuart Weinzimer, the study’s head researcher. Such a device can improve the ease and effectiveness of managing blood sugar, a difficult task that diabetics must do several times a day -- before meals, and sometimes at night.

“The person ideally doesn’t have to be involved in taking the insulin at all,” said Weinzimer, an associate professor of pediatric endocrinology at Yale University School of Medicine. Diabetic patients wake up multiple times a night to check their blood sugar, he said.

For Type 1 diabetics, whose bodies don’t produce enough insulin, night-time is especially dangerous because the patients aren’t awake to monitor their blood sugar, he said.

Simple Algorithms

The patients in the study were hooked to a Medtronic Inc. glucose monitor, which sent a signal to a laptop computer, Weinzimer said. The computer ran algorithms to determine how much insulin, if any, to release, and then sent a signal to the patients’ insulin pump while they slept in a hospital.

Although the study used a laptop, the algorithms are simple enough that they could be run on a smaller device, Weinzimer said. As the technology progresses, the monitor and the pump will be combined, he said.

The study also examined what happened when patients exercised during the day, and found that walking briskly on a treadmill for an hour provided an additional benefit.

At night, patients using the pancreas-mimicking pump had blood sugar levels within target 72 percent of the time, compared with 52 percent of those who also exercised but used insulin pumps.

“Exercise is obviously part of a healthy lifestyle,” Weinzimer said. “But for patients with diabetes, it can have unexpected effects on blood sugar. It hits at nighttime, when your surveillance is limited.”

Less Hypoglycemia

The study in exercise showed two incidents of hypoglycemia, abnormally low blood sugar, when the patients were on the monitoring device, compared with eight when they pumped their own insulin on sedentary days. When patients exercised, there was one incident of hypoglycemia at night on the artificial pancreas, compared with 14 with the insulin pump.

Weinzimer hopes to be able to set up a system for patients outside of a hospital environment about years from now. His current focus is increasing the accuracy of the blood glucose sensors, to make that feasible, he said.

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