Fasting- and meal-stimulated peptide hormone concentrations before and after gastric surgery for morbid obesity.

The influence of morbid obesity and of gastric surgery operation in circulating peptide hormone concentrations was studied in 26 patients. Plasma hormone levels were determined in the fasting state and after a standardized test meal before and six to nine months after gastric surgery. Before surgery fasting and postprandial blood glucose and hormone levels did not significantly differ in morbidly obese subjects from those in obese or normal subjects, except that in morbidly obese subjects, postprandial gastrin concentration remained at peak levels and did not return to fasting levels 120 minutes after the test meal. An average weight loss of 92 lb following the gastric surgery operation was accompanied by a decrease of fasting glucose and insulin levels and a decreased postprandial insulin response. There were no significant differences in plasma levels of pancreatic glucagon, of pancreatic polypeptide in the basal state, or of pancreatic glucagon after the test meal between the preoperative and postoperative groups. As compared to preoperative values, fasting gastrin levels decreased after surgery, the postprandial release of gastrin was virtually absent, and that of pancreatic polypeptide reduced. The significance of altered postprandial pancreatic polypeptide response and of the reversal of prolonged postprandial hypergastrinemia to a state of low circulating gastrin levels following gastric surgery on gastrointestinal secretion and mucosa remain to be determined.