A medical apparatus for supplying a medication fluid into an organism and for detecting a substance of the organism is disclosed. The medical apparatus has a casing, cannula, and an insertion needle. The casing has a chamber accommodating the medication fluid and an opening in fluid communication with the chamber. The cannula has a lumen in fluid communication with the chamber. The insertion needle has a receptacle. A portion of the insertion needle is removably arrangeable with the lumen. The receptacle is configured to at least partially receive a sensor system for detecting the substance of the organism. A seal is adapted to annularly sealingly surround a portion of the sensor system when the insertion needle is removed from the opening and the portion of the sensor system is arranged in the opening.
