medwireNews: The Medtronic MiniMed Advanced Hybrid Closed-Loop (AHCL) system delivers better glycemic control than the currently approved 670G system, shows the international FLAIR trial.
The upgraded system – to be known as the MiniMed 780G – uses a control algorithm based on that in the 670G system, but adds the ability to set different glucose targets and also incorporates automatic correction boluses from the MD Logic algorithm.
The FLAIR study directly compared the two systems in a randomized crossover design, making it the first trial to have a commercially available closed-loop system as a comparator, noted Richard Bergenstal (International Diabetes Center at Park Nicollet, Minneapolis, Minnesota, USA), who presented the findings at the virtual ADA 80th Scientific Sessions.
After a run-in period, the 111 people with type 1 diabetes who completed the study used the systems over two 12-week periods in a randomly assigned order.
The researchers recruited people aged 14–29 years, which Bergenstal described as “the toughest of the tough” in terms of achieving good glucose control.
Within that, they aimed for a very broad study population, ranging from people using multiple daily injections (20%) and not using continuous glucose monitoring (CGM; 38%) to people already using the MiniMed 670G (13%). Average glycated hemoglobin (HbA1c) was 7.9% (63 mmol/mol), but there was a wide range, with 27% of people having levels below 7.5% (58 mmol/mol) and 14% having levels of 8.6–11% (70–97 mmol/mol).
The primary study outcome was the amount of time spent with glucose levels above 180 mg/dL (10 mmol/L) during the daytime; this averaged 42% at baseline, 37% with the 670G, and 34% with the AHCL.
This significant 3% reduction in time over 180 mg/dL among patients using the AHCL did not come at the price of increased hypoglycemia; the corresponding averages in time spent with glucose lower than 54 mg/dL (3.0 mmol/L) over a 24-hour period were 0.46%, 0.50%, and 0.46%.
The average glucose level was lower, and the time in range (TIR; 70–180 mg/dL, 3.9–10.0 mmol/L) was higher with the AHCL than 670G system at almost every timepoint during 24 hours. Average time in range was 67% versus 63% for the two systems, respectively.
Bergenstal noted that the results were consistent for participants aged 14–20 years and those aged 21–29 years and for those with baseline HbA1c at or below 8.5% (69 mmol/mol) versus higher, and that the improvements were seen regardless of whether or not participants had used diabetes technologies prior to enrollment.
Indeed, he noted the particularly large improvement in TIR among participants using multiple daily injections with no CGM, from 45% at baseline to 65% and 63% with the AHCL and 670G systems, respectively.
Bergenstal commented that prior use of technology is often an entry requirement for trials of closed-loop systems, and said: “So I’m making a plea not to exclude people just because they haven’t previously used technology.”
When study participants were using the 670G system, they used an average of 50 Units of insulin per day, of which 49% was in bolus form. This increased to 55 Units and 64% with the AHCL, with 36% of the bolus units coming from the autocorrection boluses.
Bergenstal attributed the high proportion of insulin from autocorrection boluses to the “unique” behavior of adolescents around taking boluses for food, and displayed some individual user data demonstrating how the autocorrection boluses kept the users within target when they omitted to bolus for food.
“I think this autocorrection for adolescents, and maybe for many others, may be an important feature,” concluded Bergenstal.
In the same session, Bruce Bode (Emory University, Atlanta, Georgia, USA) presented the results of the pivotal safety study for the AHCL system and Martin de Bock (Canterbury District Health Board, Christchurch, New Zealand) shared the findings from the New Zealand AHCL randomized crossover trial, which compared it against a predictive low-glucose suspend system.
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ADA Scientific Sessions; 12–16 June 2020