Through the use of a questionnaire, we compared the usability of FlexPen^®, a new portable prefilled insulin injector, with that of various conventional pens. The 175 diabetic patients who participated in this study were divided into four age groups. The insulin injectors were evaluated based on various usability factors including ease of gripping, weight, dosage scale legibility, ease of setting dosage, ease of pressing the injection button, stability during injection, simplicity of operation, portability and overall ease of use.
The results of the questionnaire indicated that FlexPen^® had improved usability in terms of weight, dosage scale legibility, ease of setting dosage and simplicity of operation, though there was no improvement as regards ease of pressing injection button. This aspect of usability was given low marks by subjects in the older age groups. There was no significant difference between it and the conventional pens as regards ease of gripping, stability during injection and portability. Overall, there was no big variation in evaluation scores for FlexPen^® among the four age groups.
The results of the present study indicate that FlexPen^® has many technical improvements that give it superior usability to conventional insulin pens and it may be useful for patients with disability in their fingers. However, we would like to further discuss the choice of the optimal insulin pen with doctors based on the results of this study.