Plasma glucose, insulin, glucagon, free fatty acid, ketone body, lactate and pyruvate were measured in 14 patients undergoing gastrectomy under general anesthesia with nitrous oxide and oxygen. Lactated ringer solution with glucose load (10 g.hr-1) was administered in seven patients [glucose loading group: Glucose (+)] and the other seven patients received only lactated ringer solution [glucose free group: Glucose (-)]. Blood glucose increased significantly in both groups, but a significant difference appeared between Glucose (+) and Glucose (-). Plasma insulin activity and IRI/BS ratio increased in Glucose (+) and a significant difference was found between the two groups. No remarkable change in plasma glucagon level was found in both groups. Free fatty acid and ketone bodies (acetoacetate, beta-hydroxybutyrate) decreased significantly in Glucose (+), but they increased significantly in Glucose (-) and significant differences were found between the two groups. The rate of changes of beta-hydroxybutyrate was consistently higher than that of acetoacetate. Lactate and pyruvate increased significantly in both groups. These results suggest that continuous glucose loading may facilitate insulin release from the pancreas and suppress the hyperketonemia and hyperlipidemia during partial gastrectomy.