Endocrine Abstracts

Introduction: Insulinomas are rare, neuroendocrine tumors of the pancreas that cause recurrent hypoglycemia. Diagnosing them can be challenging due to nonspecific symptoms and difficulty in localizing the tumor. This case illustrates the difficulties in detecting an insulinoma over a prolonged disease course.

Case Presentation: A 56-year-old female presented with recurrent episodes suggestive of hypoglycemia. Her first episode occurred in 2018, with fainting and a blood glucose of 2.7 mmol/L. Prior to this, she experienced two episodes: one after a light lunch and walk with fatigue, blurred vision, imbalance, another after breakfast and cycling, where she became shaky 40 minutes later. Symptoms occurred at varying times, without a clear fasting-related pattern, she also noted weight gain. The patient was not on any medications and had no significant family history.

Examination: Her BMI was 33 kg/m², bp: 136/93 mmHg. Cardiovascular, respiratory, abdominal examinations were normal. No unusual rashes /acanthosis nigricans

Investigations: In 2018, oral GTT did not show reactive hypoglycemia, and C-peptide and insulin levels were appropriate for the glucose levels. Prolonged fasting revealed a glucose of 2.8 mmol/L but did not meet hypoglycemia criteria. She was advised to avoid prolonged fasting and consume low-GI foods. In 2022, the frequency of symptoms increased, prompting re-investigation. A 72-hour fasting test showed glucose 2.4 mmol/L elevated C-peptide (526 pmol/L), insulin (31 mU/L). Pancreatic CT was normal. She was discussed at Mdt. Doctate scan ordered and was normal. A year later abdominal pain and diarrhea revealed normal abdominal ct.

Management and Conclusion: The results suggested insulinoma but imaging did not reveal any lesion, she was referred to tertiary center. A repeat CT scan identified a small pancreatic lesion, Endoscopic US confirmed an insulin-secreting tumor, Ki-67 index 16%. Surgery was performed six years after the initial presentation. This case depicts challenges in diagnosing rare causes of hypoglycemia.