A medical device includes a base having a first surface to be secured to a patient's skin. A first insertable member has a length portion extending from the first surface of the base for insertion. A second insertable member has a length portion extending from the first surface of the base for insertion through the patient's skin. The first insertable member includes a sensor member for sensing a biological condition, and the second insertable member includes an infusion cannula for infusing an infusion media. The distal end of the first insertable member and the distal end of the second insertable member are spaced apart by a first distance of at least 5.0 mm, for reducing interference of the infusion media from the infusion cannula with an operation of the sensor member.