The system has a housing (12) with at least two separated chambers (13,14), at least one sensor (3) in a first chamber under sterile conditions and a data medium (11) in a second chamber with calibration data for the sensor. The housing is adapted to an interface of a base station (2) so that the sensor contained within the housing and the associated data medium can be connected to the base station by applying the housing to the interface. An independent claim is also included for the following: (A) a packaging system for replacement components of an inventive system (B) and a method of packaging a sensor for in vivo measurement of an analyte concentration.