A system for managing a patient's glucose level includes a glucose sensor to generate and store data signals for measurements of the patient's glucose level made by the glucose sensor; an insulin pump; and sensor electronics operatively coupled to the glucose sensor, the sensor electronics comprising a memory storing one or more predetermined characteristics associated with the sensor electronics; and a computing device in electronic communication with the sensor electronics. The computing device comprises a processor configured to operate the sensor electronics to (i) receive the generated data signals, (ii) obtain the one or more predetermined sensor characteristics from the memory and (iii) execute a closed-loop algorithm to provide insulin delivery instructions to an insulin pump by at least using the data signals and predetermined characteristics.