Fasting hypoglycaemia may also be seen with large retroperitoneal mesenchymal tumours secreting Insulin-like growth factor I/II associated with weight loss and cachexia
About
- Typically small benign tumours of the pancreatic beta cells
- May be part of MEN Type 1 syndromes
- Fulfills Whipples triad - see below
Clinical
- Hypoglycaemic symptoms - palpitations, sweating, hunger, anxiety etc
- Patients learn to eat frequently to avoid fasting hypoglycaemia
- Therefore patients are usually obese rather than thin
Whipple's Triad
- Symptoms come on with fasting or exercise
- Hypoglycaemia documented with symptoms
- Glucose relieves symptoms
- Now would add that Insulin is inappropriately high
Investigations
- They are typically small tumours and difficult to localise
- Diagnosed with a low blood glucose and high Insulin level and C-peptide
- Prolonged fasting up to 72 hours to provoke symptoms
- A high Fasting Insulin and low C-peptide suggests exogenous Insulin
- High resolution Abdominal CT/MRI of pancreas
- Selective intraarterial calcium infusions (IACS): can show increase in insulin secretion after infusion of the splenic and superior mesenteric arteries. Then needs to hunt for the insulinoma.
Management
- ABC, treat hypoglycaemia, 10% Glucose may be needed
- Surgical excision is usually curative: there may not be a tumour but diffuse islet cell hyperplasia (nesidioblastosis) needing distal pancreatectomy
- Diazoxide is used to reduce hypoglycaemia when the tumour not resectable as too small to be found or malignant or comorbidities (inhibits Insulin release)
- Somatostatin analogues mat help e.g. octreotide