Physical exercise is known to result in hypoglycaemia in many insulinoma patients. A physical exercise was found to be necessary in some insulinoma patients to make the correct diagnosis (Jarhult et al. 1981). The percentage of patients with negative fast test and meal test who could be diagnosed to have insulinoma by a physical exercise test remains to be established. In selected patients a "physical exercise test" under medical supervision, with at least serial measurements of plasma glucose and serum insulin, C-peptide and proinsulin
