Potential Insulin Underdelivery from Prefilled and Reusable Insulin Pens in Cases of Premature Needle Withdrawal: A Laboratory Evaluation

Abstract

Background:

Devices for the treatment of diabetes are not always used as recommended in good practice. Our aim was to evaluate potential insulin underdelivery in cases of premature needle withdrawal after injection with insulin pens, which is a commonly observed misuse, especially in young type 1 diabetes patients.

Materials and Methods:

Potential insulin underdelivery was evaluated using five prefilled insulin pens (lispro Kwikpen^® [Eli Lilly, Indianapolis, IN], aspart Flexpen^® [Novo Nordisk, Bagsvaerd, Denmark], glulisine Solostar^® [Sanofi, Paris, France], detemir Flexpen^® [Novo Nordisk], and glargine Solostar^® [Sanofi]) and three reusable insulin pens (Humapen^® Luxura HD with lispro cartridge [Eli Lilly], Novopen^® Echo with aspart and detemir cartridge [Novo Nordisk], and JuniorSTAR^® with glulisine and glargine cartridge [Sanofi]) in a laboratory. For each pen and insulin, we simulated premature needle withdrawal 2 and 3 s after an insulin injection of 5 and 10 units, respectively.

Results:

With prefilled pens, mean potential insulin underdelivery was 0.43±0.30 and 0.44±0.32 units after injection of 5 and 10 units, respectively. With reusable pens, mean potential insulin underdelivery was lower (0.29±0.13 and 0.29±0.12 units after injection of 5 and 10 units, respectively; P<0.001). The results were heterogeneous across pens, ranging from 2.6%/1.6% to 20.2%/8.6% of the selected insulin dose for prefilled/reusable pens, respectively (P<0.001).

Conclusions:

Potential insulin underdelivery varies across prefilled and reusable insulin pens but may represent up to one-fifth of the total injected dose. Clinicians should be aware of the potential consequences of premature needle withdrawal and should reinforce insulin injection education.