BACKGROUND: The objective of this study was to assess feature preferences,patient acceptance, reliability, and safety of the new Lilly Humulin/Humalog 3.0 ml prefilled insulinpen in a clinical setting. MATERIAL/METHODS: A total of 330 patients in Croatia with type 1 or type 2diabetes mellitus who required at least one injection of insulin per day were treated with Humulin 30/70or Humalog for 4 to 6 weeks using the new prefilled pen. Questionnaires concerning various aspects ofthe pen performance were administered at endpoint. RESULTS: The features of the Lilly 3.0 ml pen deviceranked most highly by patients (% of excellent or good ratings) were cartridge visibility (93%), attaching/replacingneedles (93%), ease of dose correction (92%), checking insulin flow (90%) and dialling of insulin dose(89%). Features of the pen device rated most highly by patients in comparison with the delivery systemsused before the study and the percentage of patients rating those features as much better or better wereease of dose correction (74%), cartridge visibility (67%), audible dialing clicks (55%) and size of dosenumbers (52%). Most respondents (78%) preferred single-unit versus two-unit dosage increments. The majorityof patients rated the new prefilled pen as being more convenient and easier to use, and indicated thatit represented a significant or modest an improvement over their previous insulin injection method. CONCLUSIONS:The results of this study indicate that the new Lilly 3.0 ml prefilled pen is acceptable for patientswho were previously using either reusable devices or the traditional syringe and vial.

Keywords: Adolescent, Aged, 80 and over, Croatia, Diabetes Mellitus, Type 1, Diabetes Mellitus, Type 2, Equipment Design, Injections, Insulin, Patient Compliance, Patient Education, Patient Satisfaction, Questionnaires, Reproducibility of Results, Syringes