Hyperinsulinemic hypoglycemia developing late after gastric bypass

Background: Post-gastric bypass hyperinsulinemic hypoglycemia causing confusion and loss of consciousness was recently described, and appears to be an important late complication of gastric bypass surgery. We report 3 additional patients with this disorder, and describe their responses to high and low carbohydrate test meals. Patients: The patients were 1 woman and 2 men ranging in age from 50 to 65 years who underwent Roux-enY gastric bypass (RYGBP) for morbid obesity. 15 to 37 months after surgery, they started to have episodes of postprandial confusion and loss of consciousness. Results: When given high carbohydrate mixed meals, all 3 demonstrated peak plasma glucose >200 mg/dl (11.1 mmol/l) and peak serum insulin >300 mu U/l (1800 pmol/1). Although serum insulin declined rapidly, all 3 developed hypoglycemia with plasma glucose <42 mg/dl (2.3 mmol/l). Following low carbohydrate test meals, there was little change in plasma glucose or serum insulin and no hypoglycemia. Conclusions: Our data suggest that low carbohydrate diets may be effective in treating post-gastric bypass hyperinsulinemic hypoglycemia. We hypothesize that rapid digestion and absorption of carbohydrate is an important feature of this disorder and may be treated with measures other than pancreatectomy.