From the beginning of his medical practice he kept a diabetes registry, the first of its kind in the world. His carefully assembled data from his medical ledgers eventually allowed him to predict a global diabetes epidemic that is evident today. In 1908, in conjunction with physiologist Francis G. Benedict, Joslin carried out extensive metabolic balance studies examining fasting and feeding in patients with varying severities of diabetes. His findings would help to validate the observations of Frederick Madison Allen regarding the benefit of carbohydrate- and calorie-restricted diets. The patients were admitted to units at New England Deaconess Hospital, helping to initiate a program to help train nurses to supervise the rigorous diet program.