INS and diabetes mellitus: Although there is a need to evaluate other aspects of insulin pen use, such as subjects’ preferences and adherence to therapy in cost-effectiveness and longitudinal studies, considering the increasing trend in diabetes prevalence and health charges attributed to this cause, our results showed that use of the higher-costing insulin pens is not associated with improved glycemic control, better lipid profile, or reduced heart attack and ischemic strokes in adult patients with diabetes in Iran.