Establishing a long-term profile of blood sugar level aiding self-control of the same includes periodically obtaining a specimen from a patient, and detecting a response of the specimen. Obtaining a blood sugar value of the patient based on the response, and storing the blood sugar values periodically measured. Establishing a long-term profile of blood sugar level from the measured blood sugar values in a form of chart. Furthermore, when the variation of the long-term profile of blood sugar level exceeds a standard, generating a warning signal informing the patient. When the variation of the long-term profile of blood sugar level does not exceed the standard, generating a safety signal informing the patient.