Endocrine Abstracts

Introduction: Hyperinsulinaemic hypoglycemia after gastric bypass surgery is a rare but probably underestimated complication. The mechanisms leading to hypoglycemia are complex and incompletely understood and involve several factors: A part from decreasing insulin resistance, caloric restriction and alteration of nutrient delivery, enhanced secretion of insulin and incretins (GLP1 and GIP), altered physiology of other hormones and dysregulation of counterregulatory effectors seem to play a major role. Treatment strategies include nutritional counselling with carbohydrate restriction and various medical treatments. Partial pancreatectomy is reserved for severe treatment-refractory cases.

Case report: A 53-year-old woman presented with postprandial hypoglycemia and neuroglycopenia 3 years after Roux-en-Y gastric bypass. A CGMS over 1 week demonstrated several hypoglycemic episodes typically occurring 2–3 h after meals. Endogenous hyperinsulinism was documented in a mixed meal test which was stopped after 2 h when the patient had severe neuroglycopenic symptoms and a plasma glucose of 1.9 mmol/l. ¹⁸F-DOPA-PET showed diffuse uptake within the pancreas but no focal enhancement. Despite carbohydrate restriction the patient continued to have neuroglycopenic symptoms. Diazoxide was begun but had to be withdrawn due to side effects. After discussion of other treatment options, the patient was started on liraglutide (Victoza) which was titrated to a dose of 1.2 mg daily. Frequency and severity of postprandial hyperinsulinemic hypoglycemia decreased markedly and neuroglycopenia resolved completely.

Conclusions: GLP1 analogues might be a new treatment option for hyperinsulinaemic hypoglycemia after bariatric surgery. However, the exact mechanism of action remains to be elucidated. It can be assumed that a stimulation of glucagon secretion with concurrent inhibition of insulin secretion in low blood glucose states by GLP1 analogues partly explains the stabilising effect on glucose metabolism in these patients. Nevertheless, further studies are needed.