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

AbstractInduction of tolerance to insulin, the only beta-cell-speci®c antigen in Type 1diabetes, is under testing for prevention of Type 1 diabetes in the USmulticentre trial DPT1. Recently a multicentre double-blind trial with oralinsulin in patients with recent onset Type 1 diabetes, conducted by our group,has been completed and showed that oral insulin administration at the dose of5 mg daily for one year starting at the time of disease onset had no effect onresidual beta-cell function as assessed by C-peptide secretion. A similar trialusing different doses was carried out at the same time and similarly showedno bene®cial effect on the decline of beta-cell function during the ®rst yearafter diagnosis. In this study oral insulin was administered at the daily dosesof 2.5 and 7.5 mg over a one-year period. Such results challenge the currentview that induction of oral tolerance can be established when the immuneprocess is already active.

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.