Background: The accuracy and convenience of pen devices for insulin injection have improved quality of life for patients with insulin-treated diabetes mellitus (DM). Prefilled, disposable pens have the advantage of simplicity, with minimal training and attention required and no installation of new cartridges necessary.
Objective: The aim of this study was to assess patient preference, efficacy, and safety profiles of a prefilled, disposable pen (FlexPen) and conventional vial/syringe injection method for insulin injection therapy among patients with DM.
Methods: In a multicenter, randomized, open-label, crossover study, patients with type 1 or 2 DM were transferred from previous QD or BID conventional insulin therapy to a mixture of 70% insulin aspart protamine suspension and 30% insulin aspart injection (NovoLog Mix 7030) for 4 weeks of dose optimization using their usual type of syringe. Patients were then randomly assigned to use either vial/syringe or a prefilled, disposable pen to inject the biphasic insulin aspart 7030 mixture for the next 4 weeks, followed by 4 weeks of use of the other injection device. Efficacy, safety profiles, and patient preference for the delivery systems were compared.
Results: A total of 121 patients (mean [SD] age, 57.0 [12.4] years; age range, 28-81 years; mean [SD] body mass index, 31 [5.5] kg/m(2)) were enrolled. One hundred three patients completed the study. Seventy-four percent of patients (78105) indicated a preference for the pen over the vial/syringe method (95% CI, 71%-87%), compared with 20% (21105) who preferred the vial/syringe. Eighty-five percent (88104) considered the pen more discreet for use in public (compared with 9%  for the vial/syringe), 74% (77104) considered it easier to use overall (compared with 21%  for the vial/syringe), and 85% (89105) found the insulin dose scale on the pen easier to read (compared with 10%  for the vial/syringe). Patients had statistically significant improvement in glycosylated hemoglobin values during the study (P < 0.05). No statistically significant differences in fasting plasma glucose, mean 4-point blood glucose profiles, or serum fructosamine values were found between groups. Overall, the safety profiles during treatment periods with the pen were comparable to those with the vial/syringe.
Conclusions: In this trial, differences in efficacy and safety profiles between the vial/syringe and prefilled, disposable pen appeared negligible. However, more patients expressed a preference to continue use of the pen.