Fluctuating islet-cell autoimmunity in unaffected relatives of patients with insulin-dependent diabetes.

Complement-fixing islet-cell antibodies (CF-ICA) were found in 20 out of 685 unaffected first-degree relatives of children with type 1 diabetes. During a 5-year follow-up, 7 of the 20 became diabetic, 1 continued to show the antibodies without any abnormality of glucose tolerance, and 12 subjects lost them without the disease developing. Although CF-ICA are useful as a marker of active insulitis they should not at present be used to define subjects who might benefit from preventive immunosuppression.