An injector for cm 11transcutaneously introducing a sensor into a patient, including a cannula, a sensor arranged in the cannula, a base element, a sliding element arranged displaceably on the base element in an injection direction, for transcutaneously introducing the cannula having the sensor into the patient in an injection operation. The cannula has a slot in a longitudinal direction of the cannula. The injector has a holding element arranged displaceably on the base element that, in an ejection operation, prevents the sensor from being pulled out as the cannula is withdrawn, by engaging in a distal end region of the sensor through the slot into the cannula. The holding element and/or base element have at least one fixing arrangement to automatically lock the holding element on the base element when the cannula is introduced transcutaneously into the patient. A method for transcutaneously introducing a sensor into a patient is also provided.
