Background: This study compared patient preference for Humalog® KwikPen™ 200 units/mL (insulin lispro; hereafter, IL 200 pen; Eli Lilly and Company, Indianapolis, IN) versus the Humalog KwikPen 100 units/mL (insulin lispro; hereafter, IL 100 pen; Eli Lilly and Company, Indianapolis, IN) in patients with diabetes requiring >20 units of mealtime insulin and diabetes caregivers. This study also determined which attributes had the greatest influence on pen preference selection. Methods: In this 2-period, crossover, simulated-use study, 106 participants were randomized to 1 of 8 sequences that varied the pen order (IL 100 pen or IL 200 pen) and dosing order (15 units = low dose or 50 units = high dose) for a total of 4 simulated injections. Participants then completed a self-administered questionnaire to select their overall preference between the 2 pens and then rated the importance of 11 pen attributes in contributing to their overall preference. Results: Of the 90 participants expressing an overall preference, significantly more preferred the IL 200 pen to the IL 100 pen (IL 200 pen: 80 respondents; IL 100 pen: 10 respondents; 95% confidence interval [0.81, 0.94], P < .0001). The total amount of insulin in the pen, the ease in pressing the injection button, and the amount of fluid injected were key attributes influencing IL 200 pen preference. Conclusions: Based on these key attributes, the IL 200 pen was significantly preferred over the IL 100 pen by patients with diabetes who require >20 daily mealtime insulin units or diabetes caregivers and may improve the injection experience for these patients.