This study proposes a program in which the effects of conventional treatment of insulin dependent diabetes mellitus by intermittent subcutaneous depot injection of insulin will be compared with the effects of a program of continuous subcutaneous infusion of insulin. The effects to be compared will be those on endocrine and biochemical abnormalities in diabetes, and on functional and anotomical changes associated with long-term diabetes in those organs affected by the so-called complications of the disease, the eyes, kidneys, and nervous system. A defined group of volunteer subjects will be recruited and randomly allocated to the two treatment programs. After a planning phase an initial relatively short-term study phase will be used to address the question whether the treatments result in significantly different levels of control of glycemia, and whether the given target levels of control of glycemia can be achieved by means of the infusion program described. The principal biochemical indices to be determined will be the blood glucose concentration, the proportion of glycosylated hemoglobin in the blood, the free insulin concentrations in the blood, the functions of the kidney in terms of creatinine clearance, and protein excretion, the functions of the peripheral nerves in terms of conduction velocities and latencies, and the functions and conditions of the eyes in terms of visual acuity, the features of retinopathy classified according to the so-called "Early Treatment Diabetic Retinopathy Study", and fluorescein angiography. The specified number of subjects will be assessed at 4 month intervals in terms of the so-called complications, and more frequently in terms of the control of glycemia, for a total period of two years as suggested in the RFA.