A comparison study of patient ratings and safety of 32- and 34-gauge insulin pen needles

Objective: Our aims were to compare diabetic patients’ evaluations of straight 32- and tapered 34-gauge 4-mm needles for usability and preference as well as the frequency of injection adverse events during insulin self-injection and to analyze the relationship between patients’ preferences and their background characteristics including thumb force measured by manual muscle testing. Methods: We enrolled 60 insulin-treated patients and measured their maximum thumb force. Patients were randomized into two groups (32- and 34-gauge) with reverse order of needle use: 1 week with one type of needle and the next week with the other. The usability of and preference for the needles were measured using the visual analog scale (VAS), and the frequency of injection adverse events was evaluated. Results: Mean maximum thumb strength was 83.5 ± 25.4 N, tended to decrease with age and was significantly lower in females than in males. The mean VAS scores regarding smooth insertion and pain during insulin delivery were significantly different, favoring the 34-gauge needle. However, the mean VAS scores regarding ease of pushing an injection button and overall preference showed no significant difference between the two needles. There was no significant difference in the frequency of injection adverse events including breaking needles. Conclusion: Our patients had sufficient thumb force to push the injection button regardless of needle type. Although significant differences regarding smooth insertion or pain during insulin delivery were perceived, there was no difference in overall preference between the two needles, indicating the usability and safety of the two needles are not different in clinical use.