Title : A bitter aftertaste: Nesidioblastosis emerging post-nissen fundoplication
Abstract:
Background: Hypoglycemia in non-diabetic individuals is uncommon and diagnostically challenging, especially in patients with prior upper gastrointestinal surgery. While dumping syndrome is often implicated in postprandial hypoglycemia, the presence of fasting hypoglycemia necessitates evaluation for endogenous hyperinsulinemic conditions such as insulinoma or nesidioblastosis.
Case: We report a 54-year-old man with a history of Nissen fundoplication who developed frequent symptomatic hypoglycemia, occurring both postprandially and during fasting. He experienced up to three episodes daily. Continuous glucose monitoring (CGM) confirmed persistent hypoglycemia and initial dietary modifications and pharmacologic interventions (acarbose, diltiazem) failed to control symptoms. A 72-hour fast revealed glucose <55 mg/dL with inappropriately elevated insulin, C-peptide, and proinsulin levels. Imaging ruled out insulinoma. Based on biochemical and clinical findings, a diagnosis of noninsulinoma pancreatogenous hypoglycemia syndrome (NIPHS), or nesidioblastosis, was made. Treatment with diazoxide significantly reduced hypoglycemic episodes and improved quality of life.
Discussion: This case highlights nesidioblastosis as a rare but important cause of post-surgical hyperinsulinemic hypoglycemia. While most reported are seen after Roux-en-Y gastric bypass, it can also occur following fundoplication procedures. Although postprandial hypoglycemia is often attributed to dumping syndrome, the presence of fasting hypoglycemia should raise concern for endogenous causes such as insulinoma or nesidioblastosis. CGM proved invaluable for diagnosis and safety, particularly in hypoglycemia unawareness. Pharmacologic therapy with diazoxide was effective and well-tolerated.
Conclusion: Clinicians should maintain a high index of suspicion for endogenous hyperinsulinemic disorders in post-gastric surgery patients who present with fasting or mixed-pattern hypoglycemia. Early use of CGM and targeted therapy can improve outcomes, even in the absence of surgical or histologic confirmation.