Fast-Acting Insulin Aspart Use with the MiniMedTM 670G System

Background: This study assessed the efficacy and safety of ultrarapid insulin Fiasp(R) in the hybrid closed-loop MiniMed (TM) 670G system. Methods: This was a pilot randomized double-blinded crossover study among established MiniMed (TM) 670G users comparing percentage time in range (TIR) and hypoglycemia for Novolog(R) and Fiasp. After 2 weeks optimization with their home insulin, participants were randomized to receive Novolog or Fiasp for 2 weeks, followed by the other insulin for the next 2 weeks. Data from the second week of blinded insulin use were analyzed to allow 1 week for 670G adaptation. During the second week, individuals were asked to eat the same breakfast for 3 days to assess differences in meal pharmacodynamics. Results: Nineteen adults were recruited with mean age of 40 +/- 18 years, diabetes duration of 27 +/- 12 years, and median hemoglobin A1c of 7.1% (6.9, 7.5), using 0.72 (0.4, 1.2) units/(kg center dot day). For Novolog and Fiasp, respectively, the %TIR (70-180 mg/dL) was 75.3 +/- 9.5 and 78.4 +/- 9.3; %time 180 mg/dL was 21.6 +/- 9.0 and 19.3 +/- 8.9; mean glucose was 147 +/- 12 and 146 +/- 12 mg/dL; coefficient of variation was 28.6% +/- 4.5% and 26.8% +/- 4.4%; %time in auto mode 86.4 +/- 9.2 and 84.4 +/- 9.2. All comparisons were nonsignificant for insulin type. Total daily dose (Novolog 48.8 +/- 28.4 vs. Fiasp 52.4 +/- 31.7 units; P = 0.01) and daily basal (Novolog 17.6 [15.5, 33.8] vs. Fiasp 19.1 [15.3, 38.5] units; P = 0.07) correlated with TIR and %time >180 mg/dL. For insulin delivery in auto mode there was no statistical difference in total daily dose or daily basal between arms. Paired analysis for matched breakfast meals revealed no significant differences in time to maximum glucose, peak glucose, or glucose excursion. Conclusions: In this pilot study, the use of either Novolog or Fiasp in a commercially available MiniMed 670G system operating in auto mode resulted in clinically similar glycemic outcomes, with a slight increase in daily insulin requirements using Fiasp.