On this day in 1893, a student at Harvard Medical School made the first entry in a ledger he would keep for the rest of his long career. Elliott Joslin examined a frail young Irish girl, who was suffering from diabetes. Long before he became one of the world's leading authorities on diabetes, he understood the importance of careful documentation. Keen observation of his patients helped him develop a novel approach to the treatment of diabetes. He prescribed a strict diet that regulated blood sugar levels and helped patients manage their own care. The introduction of insulin in 1921 confirmed the effectiveness of Joslin's approach. Elliott Joslin saw 15 patients a day until a week before his death in 1962, at age 93.

Unlike many other men who made Boston a center of medical innovation, Elliott Joslin was born in Massachusetts — in the town of Oxford, 40 miles west of Boston. The son of a wealthy shoe manufacturer, Elliott was an unusually focused, driven young man. He attended Yale College, graduated at the top of his Harvard Medical School class, and served an internship at Massachusetts General Hospital. After additional study in Europe, he returned to Boston in 1898 and opened a private office in the house his father had bought in the Back Bay.

Although Joslin had been interested in diabetes since medical school, he began his career as a general practitioner. Physicians who specialized in one particular disease were still rare in American medicine, and it would be almost 20 years before Elliott Joslin emerged as one of the most influential people in the study and treatment of diabetes.

Mary Higgins's case sparked his interest and convinced him of the need to chart in detail the course of a patient's illness. Joslin began keeping a diabetic ledger in 1893; Mary Higgins was the first entry in the first volume. He documented every patient he treated for the next 70 years. Eventually, his ledgers filled 80 volumes and became the central registry for diabetes in the United States, the first system for recording patient diabetes data outside of Europe.