72 year old woman presented for evaluation of recurrent hypoglycemia for 6 weeks. Hypoglycemic episodes were almost always post prandial. She has history of gastric restriction surgery 4 years ago due to obesity and subsequently lost 100 pounds over 4 years. She has no past medical history of diabetes and she does not use insulin or oral hypoglycemic agent. She has no access to these medications either. She had mental status change, diaphoresis, shaking of extremities and palpitations on initial presentation which resolved. Physical exam was otherwise unremarkable. Her initial labs including 72-hour fast during which BG did not drop below 45 mg/dL, Sulfonylurea screen was negative, beta hydroxybutyrate was elevated and her Hemoglobin A1C was 4.6. She continued to have recurrent hypoglycemic episodes requiring continues dextrose 5% infusion. A computer tomography scan did not show any pancreatic masses and magnetic resonance imaging of the brain was negative for any pituitary mass. She would become hypoglycemic despite frequent oral replacement with simple carbohydrates like orange juice. Due to recurrent hypoglycemia she had a mixed meal test with serial testing of glucose, insulin, connecting-peptide, glucagon, glucagon like peptide-1 and gastric inhibitory polypeptide were within normal. Patient was diagnosed of having an inappropriate insulin response to the ingestion of simple carbohydrates. Nutrition consult recommended placing patient on complex carbs. Patient was also initiated on Acarbose at 50mg three times daily prior to meals to help prevent hypoglycemic episodes. She had significant improvement in her hypoglycemic episodes and was discharged home with follow up with endocrinology as outpatient.
Hospitalists frequently manage patients with recurrent hypoglycemia. Endogenous hyperinsulinemia hypoglycemia has been reported to occur rarely after Roux-en-Y gastric bypass surgery. Cause of this hypoglycemia is still unclear. This case is interesting in fact that recurrent hypoglycemia occurred after gastric banding. Also, insulin concentration after mixed meals was normal, but this does not exclude hyperinsulinemia response to simple carbohydrates. This case highlights that hyperinsulinemia induced hypoglycemia should be suspected even in patients with gastric banding. Aggressive management is required during each episode. Early detection of the cause through simple methods can eliminate unnecessary testing and avoid financial burden on the patient.
Suspecting inappropriate insulin response to the ingestion of simple carbohydrates in patients with gastric banding can result in early diagnosis, management and most importantly prevent fatal effects of hypoglycemia. Specific and simple treatment strategy like dietary modification can prevent future hypoglycemic episodes in such patients.