A medical device for treating a user, the medical device comprising: a first housing portion adapted to be carried by a user; a second housing portion configured to be selectively operatively engaged with and disengaged from the first housing portion; a magnetic source having at least one of a certain magnetic field and a certain magnetic strength provided on at least one of the first housing portion and the second housing portion; a sensor for detecting at least one of the certain magnetic field and the certain magnetic strength provided on the other of the first housing portion and the second housing portion; and circuitry configured to provide a first signal in a case where the first housing portion and the second housing portion are brought together and the sensor detects at least one of the certain magnetic field and the certain magnetic strength of the magnetic source; the circuitry further configured to provide a second signal in a case where the first housing portion and the second housing portion are brought together and the sensor detects at least one of a magnetic field different from the certain magnetic field and a magnetic strength different from the certain magnetic strength of the magnetic source; characterised in that the circuitry is further configured for detection by the sensor of a gauss level of the magnetic source within a first range and detection of a gauss level that is below or exceeds the first range, which provides an indication that the first housing portion and the second housing portion are improperly connected; and in that the circuitry is further configured to provide a signal to control electronics of the medical device system to disable the medical device system or certain portion thereof if a gauss level beyond a second range is detected by the sensor a first housing portion adapted to be carried by a user; a second housing portion configured to be selectively operatively engaged with and disengaged from the first housing portion; a magnetic source having at least one of a certain magnetic field and a certain magnetic strength provided on at least one of the first housing portion and the second housing portion; a sensor for detecting at least one of the certain magnetic field and the certain magnetic strength provided on the other of the first housing portion and the second housing portion; and circuitry configured to provide a first signal in a case where the first housing portion and the second housing portion are brought together and the sensor detects at least one of the certain magnetic field and the certain magnetic strength of the magnetic source; the circuitry further configured to provide a second signal in a case where the first housing portion and the second housing portion are brought together and the sensor detects at least one of a magnetic field different from the certain magnetic field and a magnetic strength different from the certain magnetic strength of the magnetic source; characterised in that the circuitry is further configured for detection by the sensor of a gauss level of the magnetic source within a first range and detection of a gauss level that is below or exceeds the first range, which provides an indication that the first housing portion and the second housing portion are improperly connected; and in that the circuitry is further configured to provide a signal to control electronics of the medical device system to disable the medical device system or certain portion thereof if a gauss level beyond a second range is detected by the sensor