The invention is directed to lead configurations for sensors that allow for less invasive sensor replacement procedures. In one configuration, a sensor lead assembly includes an outer lead body and an inner lead including a sensor such as an electrochemical glucose sensor. The inner lead can be positioned in an inner conduit of the outer lead body. The outer lead body may be substantially permanently implanted in the patient, and the inner lead can be implanted through the inner conduit of the outer lead body. Once the sensor of the inner lead has worn out or otherwise exhausted its useful life, the inner lead can be removed, and a new inner lead can be implanted in place of the old inner lead.