Fully closed-loop insulin delivery edges closer with pramlintide–faster aspart system
medwireNews: A fully automated dual-hormone delivery system with pramlintide and faster-acting insulin aspart (faster aspart) delivers overall glycemic control that is nearly as good as that achieved with a hybrid closed-loop system with the insulin only, report researchers at the virtual 56th EASD Annual Meeting.
However, participants experienced mild, transient post-prandial hyperglycemia during the 27 hours they spent using the fully automated system. This reduced the daytime time in range (TIR) relative to that achieved with the hybrid closed-loop system and prevented the fully automated system from achieving statistical noninferiority.
The 23 study participants of the randomized crossover trial were an average age of 35 years, with an average diabetes duration of 21 years and glycated hemoglobin level of 8.1% (65 mmol/mol). They completed the study on an inpatient basis, starting each phase in the evening with a snack, followed by sleep and three meals the day after, and half the participants took part in an aerobic exercise period.
Pramlintide was delivered simultaneously with insulin, at a fixed ratio of 10 µg/U. When participants were in the dual-hormone study phase, they did not have to count carbohydrates, nor did they have to announce meals to the system; a meal-detection algorithm triggered the delivery of between one and three boluses.
The participants completed the fully automated and hybrid closed-loop study phases in a randomly assigned order after a run-in period averaging 6 days, and the TIR (blood glucose 3.9–10.0 mmol/L; 70–180 mg/dL) for these periods was 75% and 79%, respectively.
Overnight the fully automated system produced a slightly higher TIR than the hybrid system, at 92% versus 88%, and a significantly reduced time above 10.0 mmol/L, at 4.2% versus 8.3%.
But during the day, TIR was significantly lower with the fully automated system, at 67% compared with 80% with the hybrid system. Study participants spent significantly more time above 10.0 mmol/L with the fully automated than hybrid system, at 31% versus 19%, but no more time above 13.9 mmol/L (250 mg/dL; 0% for both).
This was explained by increased postprandial hyperglycemia, said presenter Michael Tsoukas (McGill University, Montreal, Quebec, Canada), with participants experiencing larger glucose excursions during the first 2 hours after eating when they were using the fully automated rather than hybrid system.
On the other hand, there was a strong trend toward reduced time in hypoglycemia with the fully automated versus the hybrid system, at 0.0% versus 2.1% (p=0.068). The number of participants requiring treatment for hypoglycemia was 11 versus 21, respectively.
The study participants also had a substantial reduction in their bolus insulin needs during the fully automated phase, at an average of 19 U versus 29 U during the hybrid phase, while basal insulin needs remained the same in both phases.
Tsoukas reported that gastrointestinal side effects were significantly more common during the fully automated than hybrid phases, at 30% versus 9%, which he said was “no surprise” given that pramlintide exerts its effects on the gastrointestinal tract. However, he suggested that a longer run-in period, or a lower ratio of pramlintide to insulin, might reduce these symptoms.
He also suggested that adjusting this ratio might influence post-prandial hyperglycemia, and added that the system should be tested in an outpatient setting.
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