Novel Hypoglycemia Metrics Detail 'Artificial Pancreas' Benefits

LOS ANGELES -- Benefits to a "closed-loop system" for monitoring blood glucose and delivering exogenous insulin in type 1 diabetes went beyond mere reductions in HbA1c, according to a manufacturer-sponsored study presented here.

Intensity of hypoglycemia (blood glucose <70 mg/dL) was reduced 43% and its volume by 71% among adults and adolescents with type 1 diabetes, as assessed with a novel composite measure called the "hypo-triad," according to Robert Vigersky, MD, of Medtronic Diabetes in Northridge, California, and colleagues.

Among pediatric patients with type 1 diabetes -- including those 7 to 13 years -- reductions of 37% in hypoglycemia intensity and 61% in volume were seen.

The "hypo-triad" included the area under the curve for blood glucose and frequency and duration of episodes with glucose <70 mg/dL.

The findings were presented at AACE 2019, the annual meeting of the American Association of Clinical Endocrinologists.

The research group also developed a "Comprehensive Glucose Pentagon" -- a separate composite that includes mean glucose level, intensity of both hypoglycemia and hyperglycemia, time spent out of range, and coefficient of variation.

Using this method of assessment, hypoglycemia was reduced by 8% in adults and adolescents and 12% in pediatric patients after initiating use of the closed loop system.

"The hypo-triad and the [glucose pentagon] provide metrics beyond the A1c. This is of great value to the healthcare provider, investigators, as well as the patients as the patient wears the CGM technology day-to-day and [the provider] is able to evaluate how the patient is getting better," stated co-author John Shin, PhD, MBA, also of Medtronic Diabetes, during an oral presentation of the findings.

This study was an analysis of previously reported pivotal trial data assessing Medtronic's MiniMed 670G hybrid closed-loop insulin delivery system. This system -- otherwise known as the artificial pancreas -- was first FDA-approved in 2016 for adults and adolescents ages 14 years and older. Last year, this approval was expanded to include children as young as age 7.

Data were gathered from continuous glucose monitors used during a 2-week run-in period and 3-month study phase of the adult and adolescent pivotal trial, as well as the pediatric pivotal trial. Reductions in intensity and volume of hypoglycemia were calculated by comparing the study phase numbers to those from the run-in period.

These post-hoc findings add to the previous trial data that found a significant 7% relative decrease in HbA1c levels -- from 7.4% to 6.9% -- in the adult and adolescent population, as well as a 44% reduction in time spent in hypoglycemia. In the pediatric trial, children saw a 5% relative reduction in HbA1c -- from 7.9% to 7.5% -- and a 36% drop in the time spent in hypoglycemia with use of this system.

"Of course these new composite metrics will require validation," Shin added, highlighting this limitation of the retrospective analysis. However, he noted with additional data, the novel metrics could help predict long-term patient outcomes besides just relying on HbA1c levels or time-in-range data.

During an open discussion period, session moderator David Lieb, MD, of Eastern Virginia Medical School in Norfolk, suggested that the Comprehensive Glucose Pentagon model could be useful for monitoring patients' quality of life as well. Shin responded that quality of life could be a variable they look at more closely in future studies.

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