A comparison of the handling and accuracy of syringe and vial versus prefilled insulin pen (FlexPen)

Diabetes Technol Ther. 2009 Oct;11(10):657-61. doi: 10.1089/dia.2009.0006.


Background: To determine the preferable method for self-injecting insulin, we compared the handling, safety, and dose accuracy of a conventional disposable syringe and vial with FlexPen (Novo Nordisk A/S, Bagsvaerd, Denmark), a prefilled pen.

Methods: Insulin therapy-naive healthcare professionals (HCPs) (n = 30), unfamiliar with insulin delivery, injected 10 U of insulin into a sponge pad using either a syringe and vial or the FlexPen, both with 30-gauge 8-mm needles, on day 1. The following day, they used the alternative method. They evaluated the handling of the two methods on device-specific questionnaires and compared overall preference on a third questionnaire. To evaluate dose accuracy, 30 insulin therapy-experienced HCPs and 20 insulin therapy-naive HCPs were asked to deliver 10 U of insulin using each method, and the amount discharged was weighed.

Results: FlexPen was rated easier to use and overall more preferable than the syringe and vial by insulin therapy-naive HCPs (P < 0.001). The pen device was more accurate than the syringe and vial when used by experienced HCPs (mean +/- SD dose delivered, 9.91 +/- 0.11 U vs. 9.82 +/- 0.25 U, respectively; P < 0.001) and by insulin therapy-naive HCPs (9.91 +/- 0.12 U vs. 9.74 +/- 0.85 U; P < 0.001).

Conclusions: Insulin therapy-naive HCPs found FlexPen easier to handle and preferable to use compared to a conventional syringe and vial. Both insulin therapy-experienced and -naive HCPs were able to deliver insulin significantly more accurately with the FlexPen than with a syringe and vial (P < 0.001).

Publication types

  • Comparative Study
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Drug Delivery Systems / instrumentation*
  • Health Personnel
  • Humans
  • Hypoglycemic Agents / administration & dosage
  • Injections / instrumentation
  • Insulin / administration & dosage*
  • Self Administration / instrumentation*
  • Surveys and Questionnaires
  • Syringes*


  • Hypoglycemic Agents
  • Insulin