Significance of early and late positive responses to insulin hypoglycaemia in patients with intact vagi.

Insulin tests were performed on 100 subjects with duodenal ulcer who had not undergone surgery. Thirty-seven per cent had ;late' positive responses to insulin. It was suggested that a late response to insulin after surgery was not necessarily an indication of ;adequate' vagotomy. The secretory responses to insulin before operation revealed no difference in peak acid concentrations or outputs between those with early and late responses. Basal acid concentrations were higher in those with late responses, though the difference was only significant when the division between early and late responses was made at 60 minutes. The distribution of the timing of the peak responses suggested that the division into ;early' and ;late' responders was artificial.