Results show how the hybrid closed loop system reduced glycemic variability, which leads to fewer long-term complications from type 1 disease.
Results from a pivotal trial for the Medtronic MiniMed 670G, the first hybrid closed-loop insulin delivery system, have been published in Diabetes Technology & Therapeutics, more than 4 months after the FDA approved the device. Touted by JDRF as the world’s first “artificial pancreas,” the MiniMed 670G will be available this spring, according to statements from Medtronic.
The trial reports what had been announced already: the hybrid closed-loop (HCL) system was safe for home use, giving users increased time in their target range, with reductions in glycated hemoglobin (A1C) and less hypoglycemia or hyperglycemia than patients had at baseline. Notably, there were no severe events of hypoglycemia or any diabetic ketoacidosis in either patient group.
The trial involved 30 adolescents, which included those 14 to 21 years of age, and 94 adults, 22 to 75 years of age, all with type 1 diabetes (T1D). Ten sites, 9 in the United States and 1 in Israel, took part in the pivotal trial. Adults had an average age of 44.6 years and had lived with T1D and average of 26.4 years. Adolescents averaged 16.5 years old and had lived with T1D an average 7.7 years.
According to the article, participants were trained on how to use the MiniMed 670G and related supplies, and they uploaded their blood glucose data using the system’s customized software every day for 2 weeks before turning on the device. After that, they uploaded data weekly. Of the 129 patients in the trial, only 4 withdrew, including 3 before the run-in phase was finished. Patients used the devices for 3 months after that.
The HCL system was used for 12,389 patient days (2977 for adolescents and 9412 for adults), Patients used the “auto mode” for an average of 75.8% of the time, or 18.2 hours per day, with adults using the auto mode slightly longer on an average day than adolescents.
From baseline to the end of the study, adolescent A1C levels dropped 7.7% to 7.1%, and adult levels dropped from 7.3% to 6.8%. The share of sensor readings that showed participants were within their target blood glucose range rose from 60.4% to 67.2% for the adolescents and from 68.8% to 73.4% for the adults.
Reducing the glycemic “roller coaster” is important for those with T1D, as the authors noted. Along with results from 2 other trials of closed-loop systems—one at the University of Cambridge and one at the University of Virginia—the results show that these systems “reduced glucose variability, which may have important implications for oxidative stress and long-term diabetes complications.”
“Based on the data presented, the HCL system could be a transformative therapeutic option for insulin-treated patients,” the authors wrote.
The ability of the MiniMed 670G or other HCL systems to prevent long-term effects of T1D, which can include vision problems, cognitive issues, or limb loss, will be important as payers decide who gets access to this device. Medicare, for example, has been limiting patient choice of insulin pumps, and for years refused to routinely pay for continuous glucose monitoring (CGM), until a decision last month to fund Dexcom’s G5 Mobile system following an upgraded FDA approval.
Garg SK, Weinzimer SA, Tamborlance WV, et al. Glucose outcomes in the in-home use of a hybrid closed-loop insulin delivery system in adolescents and adults with type 1 diabetes [published online January 30, 2017]. Diabetes Technol Ther. 2017; doi:10.1089/dia.2016.0421.