The invention concerns a base part system for a medication delivery device. The base part system to be combined with a detachable reservoir/delivery part according to the application comprises a plate (1) provided with a mounting surface (1a) and openings (12a, 12b) through which two or more subcutaneous units in the form of at least two subcutaneously positioned cannulas (22a, 22b) or at least one subcutaneously positioned cannula and e.g. a subcutaneously positioned part of a sensor extend during use. During use at least one subcutaneous unit in form of a cannula part is attached to the plate (1) with fastening means (25). The subcutaneous unit comprises a body part (7) placed above the patients skin which is provided with handling means (26) allowing a user to detach the subcutaneous unit from the plate (1) and to remove the used subcutaneous unit from the patient.
