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Glucose-responsive insulinoma in a patient with postprandial hypoglycemia in the morning

Keiji Iida1, Takeshi Ohara, Yasuhisa Hino

  • 1Division of Diabetes and Endocrinology, Hyogo Prefectural Kakogawa Medical Center, Kakogawa. iida@hp.pref.hyogo.jp

Internal Medicine (Tokyo, Japan)
|October 9, 2010
PubMed

Insights

A case study highlights glucose-responsive insulinoma, a rare cause of postprandial hypoglycemia. This condition, where insulin secretion is triggered by glucose, requires careful diagnosis in patients with reactive hypoglycemia.

Area of Science:

  • Endocrinology
  • Gastroenterology
  • Oncology

Background:

  • Postprandial hypoglycemia, particularly in the morning, can be a debilitating condition.
  • Reactive hypoglycemia is often considered, but other causes should be investigated.
  • Insulinoma, a pancreatic tumor producing excess insulin, is a rare but critical differential diagnosis.

Observation:

  • A 79-year-old obese woman presented with morning postprandial hypoglycemia.
  • Oral glucose tolerance test showed parallel insulin (IRI) and C-peptide response to glucose.
  • Prolonged fasting led to severe hypoglycemia (30 mg/dL) with inadequately suppressed insulin levels.

Findings:

  • Abdominal CT identified a pancreatic uncinate process tumor.
  • Histological examination post-surgery confirmed a benign insulinoma.
  • The case demonstrates a glucose-responsive insulinoma presenting as reactive hypoglycemia.

Implications:

  • Glucose-responsive insulinoma should be considered in the differential diagnosis of postprandial hypoglycemia.
  • Accurate diagnosis is crucial for appropriate management and to rule out malignancy.
  • This case underscores the importance of comprehensive testing for persistent hypoglycemia.

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