Hyperinsulinemic hypoglycemia developing late after gastric bypass

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.

The patients were 1 woman and 2 men ranging in age from 50 to 65 years who underwent Roux-en-Y gastric bypass (RYGBP) for morbid obesity. 15 to 37 months after surgery, they started to have episodes of postprandial confusion and loss of consciousness.

When given high carbohydrate mixed meals, all 3 demonstrated peak plasma glucose >200 mg/dl (11.1 mmol/l) and peak serum insulin >300 microU/l (1800 pmol/l). 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.

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.