Pharmacokinetics of diluted (U20) insulin aspart compared with standard (U100) in children aged 3–6 years with type 1 diabetes during closed-loop insulin delivery: a randomised clinical trial
The aim of this study was to compare the pharmacokinetics of two different concentrations of insulin aspart (B28Asp human insulin) in children aged 3–6 years with type 1 diabetes. Young children with type 1 diabetes underwent an open-label, randomised, two-period crossover study in a clinical research facility, 2–6 weeks apart. In random order, diluted (1:5 dilution with saline [154 mmol/l NaCl]; 20 U/ml) or standard strength (100 U/ml) insulin aspart was administered via an insulin pump as a meal bolus and then overnight by closed-loop insulin delivery as determined by a model predictive algorithm. Plasma insulin was measured every 30–60 min from 17:00 hours on day 1 to 8:00 hours on day 2. We measured the time-to-peak insulin concentration (t max ), insulin metabolic clearance rate (MCR I ) and background insulin concentration (ins c ) using compartmental modelling. Eleven children (six male; age range 3.75–6.96 years, HbA1c 7.6% ± 1.3% [60 ± 14 mmol/mol], BMI standard deviation score 1.0 ± 0.8, duration of diabetes 2.2 ± 1.0 years, total daily dose 12.9 [10.6–16.5] U, fasting C-peptide concentration 5 [5–17.1] pmol/l; mean ± SD or median [interquartile range]) participated in the study. No differences between standard and diluted insulin were observed in terms of t max (59.2 ± 14.4 vs 61.6 ± 8.7) min for standard vs diluted, p = 0.59; MCR I (1.98 × 10−2 ± 0.99 × 10−2 vs 1.89 × 10−2 ± 0.82 × 10−2 1/kg/min, p = 0.47), and ins c (34 [1–72] vs 23 [3–65] pmol/l, p = 0.66). However, t max showed less intersubject variability following administration of diluted aspart (SD 14.4 vs 8.7 min, p = 0.047). Diluting insulin aspart does not change its pharmacokinetics. However, it may result in less variable absorption and could be used in young children with type 1 diabetes undergoing closed-loop insulin delivery. Trial registration: Clinicaltrials.gov NCT01557634 Funding: Funding was provided by the JDRF, 7th Framework Programme of the European Union, Wellcome Trust Strategic Award and the National Institute for Health Research Cambridge Biomedical Research Centre.