Fully closed-loop insulin delivery using faster insulin aspart was as safe and effective as the same system using standard insulin aspart, but there were no clear benefits associated with the use of the faster insulin formulation, according to study results published in Diabetes Care.
While hybrid closed-loop insulin therapy is associated with improvements in glycemic control, the users of these systems still experience the burden of feed-forward actions, such as carbohydrate counting or premeal insulin bolusing to avoid postprandial glycemic excursion. In the current study, researchers aimed to assess the safety and efficacy of fully closed-loop insulin therapy using faster insulin aspart compared with standard insulin aspart in young adults with type 1 diabetes.
The double-blind randomized controlled crossover trial included participants aged 18 to 25 years from the Slovenian National Diabetes Registry who had a clinical diagnosis of type 1 diabetes, use of insulin pump therapy for ≥3 months, hemoglobin A1c <9.0%, and normal body mass index.
The participants underwent two 27-hour inpatient periods that included 40 minutes of moderate to vigorous exercise and unannounced/uncovered meals; thus, the researchers were able to evaluate closed-loop glucose control during and after physical activity. The order of the interventions was randomized. During both interventions, the fuzzy-logic control algorithm DreaMed GlucoSitter (DreaMed Diabetes, Petah Tikva, Israel) was used.
The primary end point was the difference between groups for time in range (TIR; 70-180 mg/dL) during the 27-hour study period. Secondary end points included mean sensor glucose concentrations; time spent at glucose levels <60 mg/dL, 70 mg/dL, and >250 mg/dL; postprandial glucose profiles; and amount of insulin used.
The study cohort included 20 young adults with type 1 diabetes (11 women; mean age, 21.3±2.3 years; mean diabetes duration, 13.0±4.2 years) who volunteered to participate.
The median percentage of TIR for the 27-hour observational period was 53.8% for faster insulin aspart and 58.6% for the standard insulin aspart (P =.167).
There was no difference between the groups in TIR for the overnight period (83.9% with faster insulin aspart vs 88.0% with standard insulin aspart; P =.227) or for the exercise period (79.2% and 83.3%, respectively; P =.227). The percentage of time in hypoglycemia <70 mg/dL was 0.0% in both groups.
Baseline-adjusted prandial interstitial glucose increments 1 hour after the meal were greater with faster insulin aspart compared with standard insulin aspart for all meals considered together (30.9 mg/dL vs 21.7 mg/dL; P =.017), but there was no difference between the groups for meals when considered separately.
There was a significant difference between the groups in the calculated gap between measured plasma insulin and estimated insulin-on-board levels from the insulin pump data (P =.029 at the beginning of the exercise; P =.003 at the end of the exercise; P =.004 2 hours after the exercise), with smaller differences for the standard insulin aspart group.
No reports of diabetic ketoacidosis, severe hypoglycemia, or other serious adverse events were noted during the study period.
The researchers noted several study limitations, including the short duration of the study, possible selection bias as the participants were highly motivated volunteers, and the fact that treatment was administered in supervised settings with close monitoring.
“Our observations indicate that the difference in insulin pharmacodynamics should be taken into account when optimizing insulin delivery settings in order to allow for potential additional benefits from the faster insulin formulations,” concluded the researchers.
Dovc K, Piona C, Yeşiltepe Mutlu G, et al. Faster compared with standard insulin aspart during day-and-night fully closed-loop insulin therapy in type 1 diabetes: a double-blind randomized crossover trial [published online October 1, 2019]. Diabetes Care. doi:10.2337/dc19-0895