In this study, an electronic insulin pen was designed for diabetic patients dependent on insulin use in order to prevent wrong timing and wrong dosage caused from old age, vision or mental illness. During design, the patients' necessities such as easy-to-use, have been considered. The insulin pen that can be used electronically for routine dose injections, and that is called as Bilensulin, was designed to be able to used manually in the emergency. It is aimed that the patient can set the dose easily by using the fairly simple menu of the device. Additionally, the device was designed as reusable by changing the insulin cartridge. Because the tube chamber was designed to be suitable for all types of insulin, it can be used by changing cartridge without using different pen. Dose accuracy was tested by performing insulin dose measurements on a sensitive balance, and dose of Bilensulin was compared with the three types of insulin pens. The patent has been applied for this designed electronic insulin pen. The mechanism of change of cartridge has been put into the foreground in terms of ease of use and constituted the sub-structure of the patent application. Currently, the studies on the device are continuing.