‘Gold standard’ trial tests closed-loop delivery across the age spectrum
medwireNews: A randomized trial demonstrates the efficacy of closed-loop insulin delivery in a wide range of patients with poorly controlled type 1 diabetes.
The researchers included patients from the age of 6 years, and recruited equal proportions aged younger than 22 years and aged 22 years and older. All patients had been on insulin pump therapy for at least 3 months, but had glycated hemoglobin (HbA1c) levels between 7.5% and 10.0% (58–86 mmol/mol).
The results of the 12-week randomized trial are published in The Lancet and were presented at the 54th EASD Annual Meeting in Berlin, Germany, by first author Martin Tauschmann (University of Cambridge, UK).
Forty-six patients were randomly assigned to closed-loop insulin delivery, using a modified Medtronic 640G pump and Enlite 3 glucose sensor (both Medtronic, Northridge, California, USA) with a Contour Next Link 2.4 glucometer (Ascensia Diabetes Care, Basel, Switzerland), controlled by the University of Cambridge algorithm version 0.3.46.
There was a 4-week run-in period, followed by a 12-week randomized period, during which the blood glucose of patients in the closed-loop group was within the target range of 3.9 to 10.0 mmol/L for 65% of the time.
The 40 patients in the control group, who used a sensor-augmented insulin pump, had blood glucose levels within this range for 54% of the time, amounting to a significant adjusted difference of 10.8% in favor of the closed-loop group.
There was also a significant 0.83% improvement for time in hypoglycemia (<3.9 mmol/L), with rates of 2.6% versus 3.9%, but the largest difference was for time in hyperglycemia (>10.0 mmol/L), at rates of 32% versus 42% for an adjusted difference of 10.3%.
Looking at 24-hour sensor glucose profiles, based on median glucose levels of all patients, showed “clear separation” of the curves, Tauschmann told delegates, with the main benefit seen at night.
HbA1c levels fell from 8.0% (63 mmol/mol) after the run-in period to 7.4% (57 mmol/mol) after 12 weeks in the closed-loop group and from 7.8% (62 mmol/mol) to 7.7% (60 mmol/mol) in the control group, with the significant difference of 0.36% after 12 weeks favoring closed-loop treatment.
Noting the “modest” difference in HbA1c levels, Alfonso Galderisi and Jennifer Sherr (both from Yale University School of Medicine, New Haven, Connecticut, USA) write in a linked commentary that “[t]he fact that time within range provides a wealth of data that cannot be gleaned from single or multiple HbA1c measurements highlights the meaningfulness of this metric both in clinical practice and as a research outcome.”
But they say: “The present work provides the gold standard of a randomised trial done across the age spectrum in those with glycaemic control that is more representative of what is encountered in clinical practice.”
However, patients in the closed-loop group had more unscheduled contacts during the randomized phase, at 69 versus 17 for the controls. There was one instance of diabetic ketoacidosis in a patient using closed-loop delivery, caused by infusion set failure.
“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,” say Galderisi and Sherr.
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