New strides toward artificial pancreas

Spurred on by diabetes advocates and lawmakers, researchers report continued progress toward the development of an artificial pancreas for people with type 1 diabetes.

It's probably not the first time you've heard that. For more than three decades, researchers have been tying, without success, to develop an artificial pancreas.

If its name brings to mind a man-made organ to be transplanted into the patient's body, think again. The artificial pancreas is actually an automated, closed-loop system consisting of a continuous glucose monitor, an insulin infusion pump, and a glucose meter for calibrating the monitor.

The goal is to develop an implantable system in which computer software monitors blood sugar levels, senses when the body needs insulin, calculates the dose needed, and delivers it without a person even being aware of what's happening, says Stuart Weinzimer, MD, an associate professor of pediatric endocrinology at Yale University.

The pancreas produces insulin, the hormone that regulates blood sugar levels.

So what are the new developments? Last week, the FDA released the first part of a three-pronged strategy for development of a closed-loop insulin delivery system. Meanwhile, advocates from the Juvenile Diabetes Research Foundation (JDRF) asked Congress to push research of the artificial pancreas forward, and Congress last week pressed the FDA to speed its review of the device.

And while preliminary, several studies presented this week at the annual meeting of the American Diabetes Association offer renewed hope that an artificial pancreas could become a reality within the next decade.

Future treatment of type 1 diabetes

Technological advances have led to commercial devices that continuously monitor blood sugar as well as better insulin pumps, says Robert R. Henry, MD, president of medicine and science for the American Diabetes Association.

"Blood sugar is much easier to control than even a decade ago, but a huge amount of effort and [knowledge] are still needed," he says. "And patients are still at risk for serious hypoglycemic [low blood sugar] and hyperglycemic [high blood sugar] reactions, both of which can be life threatening, as well as diabetes complications" such as eye damage, kidney failure and heart disease, he says.

As a result, the 3 million Americans with type 1 diabetes, which occurs when the body's own immune system destroys the insulin-producing cells of the pancreas, have been anxiously awaiting a closed-loop system that works.

"Hopefully the new research will translate into a closed-loop system in the next 10 years," Henry, who is also a professor of medicine at the University of California, San Diego, tells WebMD.

An artificial pancreas could save Medicare $23 million over 10 years in costs related to diabetes complications, according to a recent study.

Treatment with an artificial pancreas

In one small study, Weinzimer and colleagues found that 86% of 12 type 1 diabetes patients using a computer-controlled closed-loop system attached to the body reached target blood sugar levels at night.

In contrast, only 54% of them reached recommended blood sugar levels when they switched to a more conventional insulin pump.

With the new system, blood sugar is monitored even while a person is asleep, Weinzimer says. That's important because dangerous dips in blood sugar at night, while the patient is sleeping, are one of the greatest risks faced by children and adults with type 1 diabetes, he tells WebMD. The episodes can cause seizures and even sudden death.

After a sedentary day spent resting in the hospital, participants experienced two episodes of abnormally low blood sugar at night when they used the closed-loop device, compared with eight when they pumped their own insulin. After a day during which they exercised, there was one incident of hypoglycemia at night on the artificial pancreas, compared with 14 with the insulin pump.

Participants were hooked to a Medtronic Inc. glucose monitor, which sent a signal to a laptop computer. A program calculated how much insulin was needed and a signal was sent to the patient's insulin pump.

The computer programs can be run on a smaller device than a laptop, and the researchers plan to combine the sensor and pumping components into one unit, according to Weinzimer.

Artificial pancreas vs. conventional therapy

A British team found that a closed-loop delivery system helped to improve daytime and overnight control of blood sugar levels and reduce the risk of hypoglycemia.

Twelve teenagers with type 1 diabetes were assigned to either the artificial pancreas system or conventional insulin pump therapy. Over a 36-hour period, participants engaged in normal daily activities such as playing computer games and walks, ate regular meals and snacks, and worked out on a stationary bike for a total of 60 minutes.

Blood sugar levels were in the target range 82% of the time among patients using the closed-loop system and 55% of the time among the conventional pump group. There were 11 episodes of low blood sugar in the conventional loop group vs. nine in the closed-loop group.

"The closed-loop system may improve glucose control significantly compared to conventional [pumps]. Further adjustments are needed to optimize insulin delivery to minimize risk for hypoglycemia after exercise and around meals," says researcher Roman Hovorka, PhD, of the University of Cambridge.

In another study, researchers from the Mayo Clinic found that even a little physical activity after meals has a profound impact on blood sugar levels in people with type 1 diabetes.

The researchers plan to incorporate their data into the sophisticated software program that drives their closed-loop system, says endocrinologist Yogish Kudva, MBBS.

Clinical trials of Mayo's artificial pancreas are set to begin in November in a handful of hospital volunteers, he says. More than a dozen other trials of other closed-loops systems are either under way or in the planning stage.

These findings were presented at a medical conference. They should be considered preliminary as they have not yet undergone the "peer review" process, in which outside experts scrutinize the data prior to publication in a medical journal.

By Charlene Laino

Reviewed by Louise Chang, MD