Sugar Swing After Surgery: Hyperinsulinemic Hypoglycemia With Possible Nesidioblastosis After Roux-en-Y Gastric Bypass Surgery

Abstract

Bariatric surgery is a procedure performed to achieve weight loss and manage obesity. However, it can result in various complications including post-surgical hypoglycemia. Nesidioblastosis is a rare hypoglycemic syndrome marked by diffuse hyperplasia of pancreatic β cells with distinct histologic features. Recent case reports have indicated an association of nesidioblastosis with certain bariatric procedures, often specifically linked to Roux-en-Y gastric bypass (RYGB) surgery. In this case report, we describe a 78-year-old male with a complex medical history who presented with altered mental status and severe hypoglycemia (13 mg/dL), despite having no history of diabetes or use of hypoglycemic medications. The patient's clinical condition improved after receiving a 50% intravenous dextrose injection and subsequently placed on a 10% dextrose infusion. Adrenal insufficiency was ruled out with normal cortisol level, and tests for β-hydroxybutyrate, dehydroepiandrosterone (DHEA) sulfate, and hypoglycemia panels were all negative. However, further investigations were significant for elevated serum insulin, C-peptide, and proinsulin levels. The patient then underwent an abdominal computed tomography (CT) scan, which revealed a grossly normal liver, spleen, pancreas, and adrenal glands, along with evidence of prior gastric bypass surgery. Further evaluation confirmed a history of Roux-en-Y gastric bypass surgery, which was performed to address morbid obesity and obstructive sleep apnea. Following the procedure, the patient began experiencing hypoglycemic episodes. Subsequently, the patient was diagnosed with hyperinsulinemic hypoglycemia with possible nesidioblastosis. This diagnosis was made based on severe recurrent postprandial hypoglycemia, accompanied by elevated endogenous insulin production, and a pancreas that appeared grossly normal on imaging. The patient was treated with acarbose to prevent carbohydrate-driven blood sugar and insulin spikes, octreotide to inhibit insulin secretion, and dietary guidance to avoid high glycemic index foods. This case emphasizes the potential link between bariatric surgeries and metabolic disturbances, underscoring the importance of identifying uncommon hypoglycemic syndromes.