Dumping syndrome is a sequel of gastric surgery in adults and Nissen fundoplication in children. The syndrome is characterized by various gastrointestinal symptoms as well as irritability, diaphoresis and lethargy. Shortly after a meal, symptoms are associated with hyperglycemia (early dumping), followed by late dumping symptoms associated with reactive hypoglycemia. Several therapeutic and dietary manipulations failed to control these symptoms in previous reports as well as in an infant we have followed after Nissen fundoplication. Acarbose, an alpha-glucosidase inhibitor, has been used sporadically in adults after gastric surgery, but only once in children. In most of these studies, the effect of acarbose (on reactive hypoglycemia) was evaluated over several hours postprandially or after oral glucose load. In our study, we recorded glucose dynamics by a continuous glucose monitor system over 2 to 3 days before and during acarbose treatment, while the patient was on a well-controlled diet. These measurements (720 before and 832 on therapy) suggested that both early and late dumping symptoms are causally related to the rate of glucose elevation and decline, rather than to glucose peak and nadir, respectively. Acarbose attenuated both postprandial glucose hyperglycemia and reactive hypoglycemia, which subsequently led to a significant reduction in dumping symptoms. In a follow-up of 14 months, acarbose was well tolerated and the frequency of dumping symptoms was remarkably reduced.