The invention concerns a measuring device for the optical analysis of a diagnostic test element (10) comprising a light source (16), a photodetector (24) and a device (12) for positioning the test element (10) between the light source (16) and photodetector (24) where the light source (16) has one or several organic light-emitting diodes (OLEDs) and the OLEDs (14) for a composite structure with an imaging optics (20) and/or a photodetector (24) by means of a support substrate.