Not Just an Accident: A Case of Insulinoma

Abstract

Insulinomas are a rare cause of recurrent hypoglycemia in non-diabetic patients. Diagnosis requires hypoglycemia (plasma glucose <50 mg/dL), neuroglycopenic symptoms, and prompt relief of symptoms following the administration of glucose, known as Whipple's triad. The gold standard diagnostic tests are measuring insulin, C-peptide, and glucose during a 72-hour fast. In the preoperative period and in patients with unresectable or metastatic tumors, medical management with diazoxide and octreotide can be considered for recurrent hypoglycemia.We present a case of insulinoma in a 37-year-old woman who initially presented after a seizure-related motor vehicle accident. Upon admission, her initial glucose level was 32 mg/dL, indicating a likely hypoglycemic seizure. During her hospitalization, she had recurrent episodes of fasting and postprandial hypoglycemia, ranging from 32-70 mg/dL. She exhibited the characteristics of Whipple's triad when values dropped below 50 mg/dL. These episodes necessitated continuous infusions of 10% dextrose. Tests for insulin autoantibodies, sulfonylurea screens, and thyroid function yielded unremarkable results.A 72-hour fasting test was initiated to investigate potential endogenous causes of excessive insulin production. Laboratory results from a venous glucose level of 46 mg/dL indicated a notable rise in C peptide and insulin levels, alongside beta hydroxybutyrate suppression, all of which fulfilled the diagnostic criteria for insulinoma. An abdominal magnetic resonance imaging (MRI) unveiled a 1.3 cm mass in the pancreatic tail.This case emphasizes the importance of employing a focused approach when evaluating non-diabetic individuals displaying hypoglycemia with positive Whipple's triad. This targeted method not only enables early detection of this rare condition but also assists in eliminating other common causes of recurrent hypoglycemia in non-diabetic individuals. Moreover, in addition to this diagnosis being rare, it is important to note that patients with insulinomas typically do not exhibit a glucose level low enough to induce seizures during their initial presentation.