Oral insulin and the induction of tolerance in man: reality or Fantasy?

Induction of tolerance to insulin, the only beta-cell-specific antigen in Type 1 diabetes, is under testing for prevention of Type 1 diabetes in the US multicentre trial DPT1. Recently a multicentre double-blind trial with oral insulin in patients with recent onset Type 1 diabetes, conducted by our group, has been completed and showed that oral insulin administration at the dose of 5 mg daily for one year starting at the time of disease onset had no effect on residual beta-cell function as assessed by C-peptide secretion. A similar trial using different doses was carried out at the same time and similarly showed no beneficial effect on the decline of beta-cell function during the first year after diagnosis. In this study oral insulin was administered at the daily doses of 2.5 and 7.5 mg over a one-year period. Such results challenge the current view that induction of oral tolerance can be established when the immune process is already active. Copyright (C) 2000 John Wiley & Sons, Ltd.