Insulin dependent diabetes (IDD) most often results from the autoimmune destruction of pancreatic beta cells. During this process, autoantibodies to islet cell constituents (islet cell cytoplasm, 64KDa protein [GAD]) and to insulin arise and can be used for disease prediction if found before onset or for classification at onset in cases in which type of diabetes is not clear. Approximately 4-5% of immediate family members have at least one of these antibodies. The younger the age and the higher the antibody titer, the greater the chance of IDD developing. Because studies using immunosuppression in newly-diagnosed IDD have shown transient prolongation of beta cell function, efforts to use such therapies prior to diabetes onset may prevent beta cell destruction and clinical disease. A multicenter trial is underway in Florida to screen relatives for diabetes-related antibodies and then to enter those found positive and at increased risk in a study to prevent diabetes. Details of the study and its rationale are presented.