Last updated: October 2, 2025
Insulinomas are the most common functional pancreatic neuroendocrine tumors, occurring at about 4 cases per million annually. They mainly affect middle-aged individuals, often sporadic, but can be associated with MEN-1, VHL, NF1, and tuberous sclerosis. About 10% are multiple, less than 10% are malignant, and 5–10% are linked to MEN-1, which can include multiple and potentially malignant tumors.
Hyperinsulinemia from insulinomas causes Whipple’s triad: hypoglycemia, serum glucose <40 mg/dL, and symptom relief with glucose. Symptoms include neuroglycopenic signs (confusion, seizures) and autonomic symptoms (sweating, tremors). Insulinomas can cause hypoglycemia during fasting or after meals.
Diagnosis involves supervised fasting (up to 72 hours) with measurements of insulin, C-peptide, and proinsulin to confirm endogenous hyperinsulinemic hypoglycemia, excluding other causes like exogenous insulin or secretagogues. Elevated C-peptide and proinsulin improve diagnostic accuracy.
Surgery is first-line and highly effective, with a 5-year disease-free rate of 100%. Non-invasive imaging may miss small tumors; if so, selective arterial calcium stimulation with hepatic venous sampling is recommended. Medical options include diazoxide and octreotide for those who cannot undergo surgery. Accurate localization is crucial for successful removal while preserving pancreatic tissue.
Presentation
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Anatomy
Indications
To successfully remove the tumor while preserving healthy pancreatic tissue, the insulinoma must be precisely identified and localized. However, insulinomas are often challenging to detect with non-invasive imaging because they are typically small at presentation and can be located anywhere in the pancreas. If non-invasive methods fail to locate a suspected insulinoma, selective arterial calcium stimulation with hepatic venous sampling should be considered.
Contra Indications
- None specific
Workup
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Material
Essentials
- 4-F or 5-F vascular sheath for access via the common femoral vein
- 4-F or 5-F vascular sheath for access via the common femoral artery
- Cobra or reverse-curve catheter for arterial selection
- Digital subtraction angiography (DSA) equipment for breath-hold imaging
- High-flow microcatheter (coaxial) for selecting distal splenic, proximal splenic, common hepatic, proper hepatic, and gastroduodenal arteries
- Contrast media for injection and angiography
- Diluted calcium gluconate 10% in saline (~0.025 mEq Ca²⁺/kg) for insulinoma stimulation
- Secretin (30 units in 5 mL saline) for gastrinoma stimulation
- Blood collection supplies (tubes, syringes) for obtaining 5-mL samples before and after stimulation, including at 30, 60, 120, and optionally 210 seconds for gastrinomas
- Labels for samples and labeling materials
- Serum gel tubes for insulin and gastrin samples
- Ice and freezer storage for sample preservation
- Equipment for glucose monitoring during the procedure
Hepatic Venous Sampling
* 6 Fr short sheath (right internal jugular vein)
* no flush 6 Fr 65 cm Cobra catheter, with added side hole
* 42 labeled 10 cc syringes
Selective Arterial Calcium Stimulation
* 5 Fr short sheath (right common femoral artery)
* normal saline flush 5 Fr 100 cm Sim 1 catheter 130 cm
* Progreat microcatheter and Fathom microwire
* 10% calcium gluconate solution (940 mg/10 cc) diluted to 5 cc aliquots of 1 mg/kg (0.025 mEq Ca/kg)
Non Essentials
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Positioning
Supine
Steps
- Place a 4-F or 5-F vascular sheath via the common femoral vein to select the right hepatic vein; confirm position with a digital subtraction venogram
- Insert a 4-F or 5-F sheath via the common femoral artery to select the celiac artery; use a Cobra or reverse-curve catheter
- Perform digital subtraction angiography (DSA) with breath hold to identify pancreatic arteries and anatomical variants
- Use a high-flow microcatheter coaxially to select distal splenic, proximal splenic, common hepatic, proper hepatic, and gastroduodenal arteries
- If conspicuous, add stimulation sites at the mid-splenic artery between the pancreatica magna and caudal pancreatic arteries; avoid direct selection to reduce pancreatitis risk
- Confirm arterial position with contrast injection and perform arterial stimulation:
For insulinoma, dilute calcium gluconate 10% in saline (~0.025 mEq Ca²⁺/kg)
For gastrinoma, deliver 30 units of secretin in 5 mL saline - Allow at least 10 minutes between stimulations
- Obtain blood samples:
Discard the initial aspirate, then collect 5-mL samples before stimulation and at 30, 60, 120 seconds post-stimulation; for gastrinomas, also at 210 seconds - Remove microcatheter and reposition the arterial catheter into the superior mesenteric artery for final stimulation and sampling
- Label all samples accurately; process insulin samples (serum gel, keep on ice) for chemiluminescence immunoassay; process gastrin samples (serum gel, freeze) similarly
- Periprocedural glucose monitoring is recommended, although hypoglycemia is rare
Tips & Tricks
- Groin hematoma, occurring in 3%–4% of cases.
- None specific
Folder
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Literature
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