A method for detecting in-vivo properties of a biosensor (110) is disclosed. Herein the biosensor (110) is, in interoperation with an electronics unit (202), adapted for electrochemically determining at least one value of an analyte (136) in a sample of a body fluid (140), wherein the biosensor (110) comprises at least one working electrode (120), wherein the working electrode (120) is covered by a membrane (132) and includes an enzyme (134) for providing a reaction with the analyte (136), wherein the membrane (132) has an electrical resistance and the working electrode (120) has an electrical capacitance. Further, the electronics unit (202) is adapted for measuring a raw current and a current response indicative of an admittance of the biosensor (110). Herein, the method comprises the steps of: a)providing a sensitivity-to-admittance relation of the biosensor (110)； b) measuring a raw current in the biosensor (110)； c) measuring an in-vivo current response indicative of the in-vivo admittance of the biosensor (110), wherein the in-vivo current response is measured at at least one first operating point (156) and at at least one second operating point (158), wherein the first operating point (156) is selected for providing a first characteristic value being related to the electrical resistance of the membrane (132), and wherein the second operating point (158) is selected for providing a second characteristic value being related to the electrical capacitance of the working electrode (120)； d) determining an analyte (136) value in a sample of a body fluid (140) by using the raw current and compensating an in-vivo sensitivity drift in the biosensor(110) by correcting the measured value for the raw current by determining an actual value of the sensitivity by using the first characteristic value, whereby the sensitivity-to- admittance relation as provided during step a) is taken into account；and e)monitoring a fail safe operation of the biosensor (110) based on the first
