Use of Pens versus Vials for Insulin Delivery

San Francisco—It is estimated that diabetes affects 7.5% to 7.9% of Americans and the estimated annual economic burden of type 2 diabetes in the United States is $159.5 billion. Patient outcomes are affected by various factors, including the method utilized to deliver the proper type of insulin at the proper time. Research has shown that patients exhibit a preference for pens over syringe/vial as an insulin delivery mechanism.

Researchers recently conducted a retrospective analysis to compare insurance claims of a nationwide sample of patients with type 2 diabetes who initiated mealtime analog insulin therapy with either a prefilled pen or conventional syringe/vial. They presented analysis results at a poster session at the AMCP meeting. The poster was titled Outcomes Associated with the Use of Mealtime Insulin Pens versus Vials in Patients with Type 2 Diabetes.

The primary objective of the analysis was to compare medication adherence, hypoglycemic events, and changes in HbA1c levels among adults who initiate mealtime insulin therapy with a pen (n=4429) or syringe/vial (n=3645). Data from the i3 InVision™ DataMart database for the time period January 2, 2006, through June 30, 2010, were used in the analysis.

Adherence was measured using the adjusted medication possession ratio (MPR), calculated as the usual MPR multiplied by the ratio of average number of days between refills divided by the average days’ supply. Persistence was measured as the number of days from initiation on ITT therapy until last use. The occurrence of a hypoglycemic event was measured using a previously validated algorithm of International Classification of Diseases, Ninth Revision, Clinical Modification codes for using an administrative database to examine hypoglycemia. Change in HbA1c was assessed in patients with a valid HbA1c test in both the 6-month preperiod and 12-month postperiod (n=760); for patients with multiple HbA1c values in the pre- or postperiod, the test result closest to the index date was used as the preindex value while the last valid test was used as the postperiod HbA1c value.

Results revealed significant differences between the pen group and the syringe/vial group in terms of age, geographic area of residence, physician, copayment amount, prior hospitalization, number of medications prescribed, and mean Charlson Comorbidity Index (P<.001 for all comparisons).

After controlling for differences in patient characteristics, initial prescription information, and general health of study participants, the use of pens was associated with a 6.9% higher adjusted MPR (P<.001), a 19% higher likelihood of achieving an adjusted MPR threshold of ≥0.80, and a 31-day longer period of persistence (P<.001). Use of the pen compared with use of the syringe/vial was associated with a 0.38 reduction in HbA1c scores (P=.018).

There was no significant difference between the 2 groups in the likelihood of experiencing a hypoglycemic event in the postperiod.

In summary, the researchers stated, “After controlling for differences in patient characteristics, this analysis revealed that those whose insulin was delivered via pen versus a conventional syringe/vial had better adherence to insulin therapy, superior glycemic control, and no greater risk of a hypoglycemic episode during the 12-month study period.

This study was sponsored by Eli Lilly and Company.