MINIMED 670G: The insulin pump, part of a “hybrid closed loop” system, was tested with 124 type 1 diabetes patients. For more: http://tinyurl.com/zgwst7y (The Minnesota Star Tribune)

In its latest step toward the long-term goal of creating an artificial pancreas for diabetes patients, Medtronic researchers this weekend are unveiling positive data from a pivotal trial of an insulin pump designed to automatically control glucose levels with limited input from patients.

At the American Diabetes Association annual meeting in New Orleans, researchers are scheduled to present data showing that the experimental Medtronic MiniMed 670G insulin pump kept 124 type 1 diabetes patients within the desired blood-sugar range for three months without any incidents of severe hypoglycemia, diabetic ketoacidosis, or severe device-related complications.

The device also increased the time spent in the desired range, and decreased incidents of having glucose go too high or too low, which can be unhealthy and dangerous.

Medtronic executives have already said that they plan to use the data from the trial in an application sometime this month to the Food and Drug Administration for commercial approval of the 670G system. The 670G is seen as the fourth step in a six-stage process to develop an almost-completely automatic "closed loop" insulin-delivery system. Work toward that goal began in the 1990s.

"The concept of a closed loop has been the dream, if you will, for a very long time," said Ben Andrew, an analyst at William Blair who has tracked diabetes technology for decades. "It's actually technically feasible today. The trick is to make it safe and reliable. And that is a very big step, even from where we are."

Type 1 diabetes happens when a person's pancreas can't produce the insulin the body needs to break down blood sugar (also called glucose) into energy. That forces the person to test glucose readings regularly and take insulin manually or with an automatic pump throughout the day.

According to an abstract of the final data from Medtronic's pivotal study of unsupervised type 1 patients using its 670G "hybrid closed loop" system, the patients were kept within the desired ranges for blood sugars 73.4 percent of the time. The same patients using a pump with less automation remained in-range 67.8 percent of the time.

The benefit was more pronounced at nighttime. Between 10 p.m. and 7 a.m., the patients using the 670G hybrid closed loop system were within range 76.4 percent of the time, compared with 67 percent with the less-advanced insulin pump system, the abstract shows.

"If you look at time in-target, time spent in low range, time spent in high range, they are all improved," said Dr. Fran Kaufman, chief medical officer for Medtronic's diabetes group. "And we see a narrowing of glycemic variability, so people stay in a narrower range, without as much high and low, which is the goal of diabetes therapy."

The glucose monitors used in the pivotal study took a live reading every five minutes for about three months, meaning the analysis captured more than 3.5 million readings over 12,389 "patient days."

The study was not a randomized controlled trial. Rather, researchers studied the glucose levels in a population of 124 type 1 patients all using the 670G hybrid closed loop system for three months, and then compared those results to glucose readings from the same patients from a two-week "baseline" period before the experimental period began.

The patients used a 670G insulin pump, plus a "fourth-generation" continuous glucose monitor and sophisticated internal computer programming inside the pump that uses past and current readings plus predictive analytics to predict future glucose levels, and then automatically increase or decrease insulin delivery.

Patients still have to manually enter their meal data into the pump, but the hybrid closed loop system is sophisticated enough to take a user's insulin sensitivity into account and also correct for errors if patients enter the wrong number of carbohydrates in their meal, among other features.

"It's delivering on the promise," Kaufman said. "Now, it's not the final promise — I think the final promise is, people would like to not have to tell the device anything, or do anything for it. That is a dream that is a little farther away. … But this can automatically do what people can't do as well."

Joe Carlson • 612-673-4779