An analysis device for in vivo determination of an analyte in a patient's body, comprising a transdermal measurement probe (2) adapted to be introduced through the skin surface (4) into the body, with a probe head (6) including an electro-chemical analysis sensor (7) with two measurement electrodes (25, 26, 27), a body-wearable probe connection unit (3) adapted to be worn on the body and for connection to the transdermal measurement probe (2), a test circuit (22) connected with the measurement electrodes (25, 26, 27), wherein after contact of the measurement electrodes (25, 26, 27) with a body fluid the test circuit (22) generates a test signal characteristic for the desired analysis result, an evaluation circuit (23) for evaluating test signals from the test circuit (22) and for generating an information about the desired analysis result, wherein the test circuit (22) is integrated in the probe head (6) as part of probe head electronics (10), the probe head (6) is coupled to light conductor (8, 18), the probe head (6) includes an optical sensor (17) for converting electrical signals from the probe head electronics (10) into light signals, and for transmitting the light signals via the light conductor (8, 18) coupled to the probe head (6), and the probe connection unit (3) contains a light receiver (28) for receiving the light signals from the measurement probe (2) for further processing.