The best insulin injection pen device for caregivers: results of injection trials using five insulin injection devices.

Background: Insulin injection pens have been primarily developed for self-injection among individuals with diabetes. However, an increased elderly population with diabetes has caused an increase in the number of patients who cannot self-inject insulin. Consequently, caregivers inject insulin to the patients ("other-injection"); however, insulin injection devices have not yet been developed for other-injection use.

Methods: We evaluated five devices-OptiClik (Sanofi-aventis, Paris, France), SoloStar (Sanofi-aventis), MirioPen without an antiskid tool (Eli Lilly and Co., Indianapolis, IN), MirioPen with an antiskid tool (Eli Lilly, Hyogo, Japan), and FlexPen (Novo Nordisk A/S, Bagsvaerd, Denmark). In all, 22 respondents (mean +/- SD age, 42.6 +/- 9.3 years [range, 26-57 years]), including 11 men (50.0%) and 11 women (50.0%), injected themselves (self-injection) and others (other-injection). Thereafter, respondents evaluated the ease of use and feel of the pen devices via questionnaires. As a result, we evaluated 220 procedures of insulin injections [22 (respondents) x 5 (devices) x 2 (self and other)] in this study.

Results: FlexPen was selected as the best device for self-injection but as the worst device for other-injection. OptiClik was selected as the second worst device for self-injection but as the best device for other-injection. Moreover, for other-injection, FlexPen was too long and less stable, had poor dial visibility, was difficult to recap, and was comprehensively inferior.

Conclusions: We identified problems that were not apparent during studies evaluating conventional self-injection. We conclude that devices meant for other-injection should have different features from those designed for self-injection and that consideration of caregivers' viewpoints is necessary for developing an insulin device specifically meant for other-injection.