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BERLIN -- A hybrid closed-loop insulin delivery system helped patients with type 1 diabetes achieve better glucose control, according to a randomized trial presented here.

With the use of a day-and-night hybrid closed loop insulin system -- consisting of an Enlite 3 glucose sensor, modified Medtronic 640G insulin pump, and the Cambridge algorithm on a smartphone device monitoring glucose levels -- patients spent nearly 11% more time within the target glucose range compared with people using a sensor-augmented pump therapy (65% versus 54%; mean difference in change 10.8%, 95% CI 8.2%-13.5%, P<0.0001).

Roman Hovorka, PhD, of the University of Cambridge Metabolic Research Laboratories in the U.K., and colleagues, also found that individuals who used the closed loop system had a significantly larger reduction in HbA1c from baseline through the end of the 12-week intervention period -- from an average of 8.3% down to 7.4% -- compared with those on the other pump therapy, who had an average drop from 8.2% to 7.7% (mean difference in change 0.36%, 95% CI 0.19%-0.53%, P<0.0001).

Presented at the annual meeting of the European Association for the Study of Diabetes (EASD), the findings of the multicenter trial were also simultaneously published online in .

"Most of the improvements are overnight," explained Hovorka, highlighting that there was a significant decrease in daytime and nighttime glucose variability with use of the closed loop.

Those who used the closed loop system also spent less time in hypoglycemia and hyperglycemia. Specifically, they experienced 0.83% (-1.40% to -0.16%, P=0.0013) less time below 70 mg/dL (3.9 mmol/L) and 10.3% (-13.2% to -7.5%, P<0.0001) less time at a glucose level above 180 mg/dL (10.0 mmol/L). Although none of the participants had any episodes of severe hypoglycemia, two individuals from each group had at least one severe hyperglycemia event.

The trial randomized 86 individuals with poorly controlled type 1 diabetes, ages 6 and older, to receive one of the systems. Following a 4-week training period, the individuals then lived freely over the course of 12 weeks. The novel algorithm on the smartphone was able to calculate the insulin infusion rate, set on the pump, every 10 minutes.

In an , Alfonso Galderisi, MD, and Jennifer Sherr, MD, PhD, of Yale University School of Medicine in New Haven, Conn., praised the trial, particularly for the closed loop's ability to increase time spent in target range across patients of all ages and baseline HbA1c. Galderisi and Sherr said they were particularly impressed with the system's ability to increase time spent in range by nearly 20% for patients who had poorly controlled diabetes and an A1c of over 8.5%.

"The present work provides the gold standard of a randomized trial done across the age spectrum in those with glycemic control that is more representative of what is encountered in clinical practice," the commentators wrote.

However, they also noted that users of the closed loop system did have more frequent contact with the study staff -- likely due to technical issues with the product. Because of the need for the patient to still fill the pump's insulin reservoir and change the infusion set, Galderisi and Sherr suggested this may potentially limit some of the usability of this as a commercial product in everyday practice.

"Current methods for detection of infusion set failures, namely patient education, will need to be replaced, or at least supplemented, by algorithms to help to alert patients to such an event promptly, to avoid serious outcomes," the editorial suggested, adding that the "development of adjunctive components that would enable the prompt detection of an infusion set failure, which is a common event even for those using conventional pump therapy, remains a crucial problem to be addressed in future trials."

In terms of the next steps for this closed loop system, Hovorka explained that the goal is not to market the system as a package, like the first-approved "bionic pancreas" -- i.e., Medtronic's MiniMed 670G hybrid system -- but instead to simply commercialize the algorithm for use with different continuous glucose monitors.

Hovorka also noted that his group has two additional studies currently in the pipeline, which will assess the use of this closed loop system in newly diagnosed type 1 diabetes patients as well as very young children between ages 1 and 7.