Noninsulinoma Hyperinsulinemic Hypoglycemia Syndrome Emerging Post-Nissen Fundoplication

Abstract Hypoglycemia presents a rare and complex diagnostic challenge, particularly in individuals with a history of upper gastrointestinal procedures such as Nissen fundoplication. Given the overlapping clinical presentations, it is essential to distinguish between insulinoma and noninsulinoma hyperinsulinemic hypoglycemia syndrome. In this report, we outline the case of a 54-year-old man with a history of Nissen fundoplication who presented with recurrent, severe hypoglycemic episodes, often occurring without warning, and significantly impairing his quality of life. Continuous glucose monitoring (CGM) revealed frequent hypoglycemia in both the postprandial and fasting states. Diagnostic evaluation excluded insulinoma but confirmed inappropriate endogenous insulin secretion, consistent with nesidioblastosis. The patient was successfully managed with diazoxide, which significantly reduced the frequency and severity of hypoglycemic events. This case underscores the importance of considering endogenous hyperinsulinemia in postfundoplication patients with unexplained hypoglycemia. It also highlights the utility of CGM and pharmacologic therapy in improving safety, enabling individualized care, and reducing the risk of hypoglycemia unawareness and its associated complications.