RT Book, Section A1 Masharani, Umesh A2 Papadakis, Maxine A. A2 McPhee, Stephen J. A2 Rabow, Michael W. A2 McQuaid, Kenneth R. SR Print(0) ID 1193133365 T1 Postprandial Hypoglycemia T2 Current Medical Diagnosis & Treatment 2023 YR 2023 FD 2023 PB McGraw-Hill Education PP New York, NY SN 9781264687343 LK accessmedicine.mhmedical.com/content.aspx?aid=1193133365 RD 2024/03/28 AB Hypoglycemia sometimes develops in patients who have undergone gastric surgery (eg, gastrectomy, vagotomy, pyloroplasty, gastrojejunostomy, Nissan fundoplication, Billroth II procedure, and Roux-en-Y), especially when they consume foods containing high levels of readily absorbable carbohydrates. This late dumping syndrome occurs about 1–3 hours after a meal and is a result of rapid delivery of high concentration of carbohydrates in the proximal small bowel and rapid absorption of glucose. The hyperinsulinemic response to the high carbohydrate load causes hypoglycemia. Excessive release of GI hormones such as GLP-1 likely play a role in the hyperinsulinemic response. The symptoms include lightheadedness, sweating, confusion and even loss of consciousness after eating a high carbohydrate meal. To document hypoglycemia, the patient should consume a meal that leads to symptoms during everyday life. An oral glucose tolerance test is not recommended because many normal persons have false-positive test results. There have been case reports of insulinoma in patients with hypoglycemia following Roux-en-Y surgery. It is unclear how often this occurs. A careful history may identify patients who have a history of hypoglycemia with exercise or missed meals, and these individuals may require a formal 72-hour fast to rule out an insulinoma.