The Diabetes Control and Complications Trial is a 21-center randomized prospective study of the effect of diabetes control on the long term complications of diabetes mellitus. The principal outcome variable is retinopathy with nephropathy, neuropathy, and cardiovascular disease being secondary end points. The planning phase (Phase I), and Feasibility study (Phase II) have been successfully completed. In addition in February 1985, the DCCT Study Group was given permission to initiate early recruitment of subjects for the Full Scale Trial (Phase III) pending the assessment of Phase II results. In accordance with the increased recruitment goals for Phase III the time commitment to the study of each of the key personnel was adjusted and additional staff was added to the University of Toronto DCCT research team. In addition the clinic facilities have been expanded to accommodate the increase in personnel and adjustments have been made to facilitate the smooth day to day operation of the clinic. Key personnel are all located in close proximity to each other. Easy access to the clinic along with comfortable and spacious waiting areas for patients have been secured. Through the use of public service radio advertising, newspaper and television interviews, personal contacts with patients and physicians, and presentations at physician and lay group meetings, the University of Toronto DCCT clinic has started screening a large cohort of patients for Phase III. Five additional subjects have been randomized for a total of seventeen to date. In addition several subjects have completed the major portion of the screening-eligibility procedure and will be scheduled for randomization in the near future. These volunteers will all continue in Phase III. Recruitment efforts will continue at the same pace until the recruitment goals are achieved. Only minor modification in the treatment protocols and end point assessments established and validated during Phase II are proposed for the full scale study. Patients at the University of Toronto DCCT center have performed very well in their assigned treatment groups.