Changes in the postoperative insulin test in relation to recurrent duodenal ulceration

The gastric secretory response to insulin changes in many patients between `immediate' tests, within two weeks of vagotomy, and `delayed' tests, done at least six months later. Patients who develop recurrent duodenal ulceration after vagotomy and pyloroplasty show highly significant increases in peak and rise in concentration and output of acid. Those who do not have recurrent dyspepsia show varied individual changes in the test results, but for the group as a whole there is no increase in the peak response and only a slight increase in the rise in acid concentration and output. These findings are interpreted as evidence for vagal recovery, either from neuropraxia or by collateral nerve sprouting, as a major factor in the production of recurrent ulceration. Indeed, it appears to be as important as the functional state of the vagi at the end of the operation. Consequently, only the delayed insulin tests can be of any value in the prediction or diagnosis of recurrence.