Methods, systems, and apparatuses for delivering therapeutic fluid to a user are disclosed. The apparatus includes a pump mechanism for pumping therapeutic fluid to the user having a reusable part which includes a housing and a disposable part configured to be inserted into the housing of the reusable part and to be connected with the reusable part. The connection of the reusable part and the disposable part enables operation of the pump mechanism and disconnection of the reusable part and the disposable part disables operation of the pump mechanism.
