In a recent study, Medtronic’s 670G, a hybrid closed loop system was found to work safely and to effectively manage blood sugar levels in type 1 diabetes patients.
The 124 patients involved in the study were between ages 14 and 75, had type 1 diabetes for at least 2 years, an A1c under 10%, and used a pump for at least 6 months. These participants were first given two weeks to learn the system equipment and then the trial lasted for 3 months and included 6 additional days at the beginning for retrieving data.
According to the researchers’ article in the Journal of the American Medical Association (JAMA), the hybrid closed-loop system included “investigational continuous glucose monitoring sensors with transmitters, insulin pumps displaying real-time glucose data, a proprietary algorithm, and blood glucose meters.” Patients were made to calibrate their sensors from time to time and to track their carbohydrate estimates for meal boluses. Each night at midnight, the system used its algorithm to automatically adjust multiple parameters.
Testing for Safety
According to the Mass Device press release, the trial tested for safety by looking at the incidence of severe low blood sugar episodes, diabetic ketoacidosis (DKA), serious adverse events and “device-related serious and unanticipated adverse events.”
There were no episodes of severe hypoglycemia (low blood sugar) or ketoacidosis during the trial. There were 28 device-related adverse events that were handled at home and 4 serious events that were not device related adverse events (appendicitis, bacterial arthritis, worsening rheumatoid arthritis and Clostridium difficile diarrhea). 117 events including 7 severe low blood sugar episodes occurred due to intercurrent illness or other causes not related to the closed-loop system.
Testing for Efficacy
The device was in closed-loop mode for 87.2% of the study period and researchers found that sensor glucose values were within the target range 72.2% of the time at the end of the study compared with 66.7% of the time at baseline.
Insulin needs increased an average of 47.5 units per day at baseline to 50.9 units per day at the end of the study. Participants gained weight over the course of the study. Median weight changed from 169.5 lb. at baseline to 171.1 lb. Glycated hemoglobin levels went from 7.4% at baseline to 6.9% at the end of the study.
The researchers recognized the limitations of the study which included a lack of a control group, restriction to relatively healthy and well-controlled patients and the short duration of the trial and an imbalance between the length of the study periods.
The Next Big Thing for Type 1 Diabetes?
The study authors wrote, “To our knowledge, this is the largest outpatient study to date and it demonstrated that hybrid closed-loop automated insulin delivery was associated with few serious or device-related adverse events in patients with Type I diabetes,”
The lead author, Dr. Richard Bergenstal of the International Diabetes Center in Minneapolis said, “The data is compelling and shows that the system’s ability to automate insulin dosing 24 hours a day has the potential to impact patients’ lives in a very meaningful way – particularly at night when it’s most challenging to maintain target blood glucose levels,”
According to the press release, a similar study in children is currently taking place. Also, study authors conceded that “Longer-term registry data and randomized studies are needed to further characterize the safety and efficacy of the hybrid closed-loop system.”
Edit: This closed loop system has now been approved by the FDA. Read more about this big announcement here.
Further reading on artificial pancreas:
The Artificial Pancreas: Safe for Children with Type 1 Diabetes
Artificial Pancreas Helps Pregnant Women with Type 1 Diabetes
The Artificial Pancreas You’ve Never Heard Of: “Genesis”
Artificial Pancreas Worked Effectively for 3 Months
Why I Can’t Get Excited About an Artificial Pancreas
Photo Credit: Medtronic