The invention relates to an assessment method to process a signal corresponding to a glucose concentration by performing a retrospective analysis, whereas the assessment contains the steps of starting the assessment initiated by a first trigger, collecting data to be analysed, analysing the collected data initiated by a second trigger, and displaying the results of the analysis. The invention further relates to a device, which is designed and programmed to perform said assessment method, consisting of at least a measuring device (45) for collecting the data to be analysed, a computing device (52) for analysing the collected data, a storage device (50) for recording the collected data and the analysis, a display (47) for visualising the analysed data, and a communication link (51) for transmitting data between the measuring device and the computing/storage device and display, respectively. The user has the opportunity of choosing the time period the analysis is performed for. By employing a user triggered and retrospective analysis of data, collected in particular during or after a relevant event such as a meal, it is ensured that the analysis relates to a certain event-specific context and therefore enhances the usefulness of the assessment of a glucose concentration.
