A patient who underwent subtotal gastrectomy develops sweating, palpitations, abdominal cramps and diarrhoea 2 to 3 hours after meals, with capillary blood glucose of 45 mg/dL at symptom onset, relieved by eating sugar. Which mechanism explains this late dumping syndrome?

• A Osmotic shift of fluid into the jejunum causing hypovolaemia
• B Duodenogastric bile reflux damaging the gastric remnant mucosa
• C Loss of gastric reservoir causing rapid gastric emptying alone
• D Exaggerated incretin (GLP-1) release producing an insulin surge and reactive hypoglycaemia ✓

Explanation

Late dumping occurs 2 to 3 hours after meals: rapid delivery of carbohydrate into the small bowel triggers an exaggerated incretin response, particularly GLP-1, driving excessive insulin secretion and reactive hypoglycaemia. Osmotic fluid shifts and vasoactive mediator release explain early dumping within 30 minutes, not the delayed hypoglycaemic episode. Bile reflux causes alkaline reflux gastritis, an unrelated post-gastrectomy problem. Acarbose or octreotide is used for refractory late dumping.

Reference: Sabiston Textbook of Surgery, 21st ed.

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