The present disclosure refers to a drug delivery system (100), comprising: a reservoir (101) containing a drug to be administered； a drug application device (103) adapted for injection or infusion of the drug； a pumping device (102) adapted to generate a flow of the drug from the reservoir (101) to the drug application device (103)； and a control system (104), comprising a pressure sensor (105) adapted to measure pressure signals indicative of a resistance against the flow of the drug, and a processing device (106) functionally connected to the pressure sensor (105). The control system (104) is configured to: detect a pressure signal indicative of the resistance against the flow of the drug while the drug is administered, by the pressure sensor (105)； compare the measured pressure signal to a reference value； and generate display data for user information and providing the display data to an output device (107) of the drug delivery system (100) if the measured pressure signal is above the reference value. The generating is comprising scheduling a test reminder for a glucose level test event, the glucose level test event scheduled for a test event time, generating display data indicative of the test reminder； and providing the display data to the output device (107) of the drug delivery system (100) at the test event time. Further, a method for operating a drug delivery system is provided.
