The present disclosure refers to a method for determining a blood glucose level for a patient, the method comprising detecting a present sensor signal in a present continuous interstitial blood glucose measurement for a patient; providing measurement data representing the present sensor signal; providing sensor signal correction data representing a patient-specific signal correction, the sensor signal correction data being determined from a former interstitial blood glucose measurement for the patient and comprising at least one of time delay data representing a patient-specific time delay Δt between a blood glucose value measured in a continuous interstitial blood glucose measurement and a blood glucose reference value measured in a capillary blood glucose measurement, and sensor sensitivity data representing, for the patient, a patient-specific sensor sensitivity for the sensor, determining corrected measurement data representing a corrected present sensor signal by applying the sensor signal correction data to the present sensor signal; and determining a blood glucose level for the patient from the corrected measurement data.