From the Guidelines
Surgical removal of the tumor, typically through enucleation or partial pancreatectomy, is the primary treatment for insulinoma, with a cure rate of over 90% for benign tumors. The diagnosis of insulinoma is often confirmed by serum insulin, proinsulin, and C peptide levels, as well as a 48- to 72-hour observed or inpatient fast, which can help identify the presence of these tumors 1.
Diagnostic Approach
Before surgery, patients should undergo multiphasic CT or MRI scans to rule out metastatic disease, and somatostatin scintography may be considered if octreotide or lanreotide is being considered as a treatment for metastatic disease 1. The Imamura-Doppman procedure, which involves injecting calcium into selective pancreatic arteries and measuring insulin levels in the hepatic vein, can also be used to localize the tumor 1.
Preoperative Management
Preoperative management includes stabilizing glucose levels with diet and/or diazoxide, and everolimus can also be considered in this scenario 1. Patients should monitor blood glucose levels regularly and carry fast-acting carbohydrates like glucose tablets or juice to treat hypoglycemic episodes. Dietary management includes eating small, frequent meals high in complex carbohydrates and protein while avoiding simple sugars.
Medical Therapy
If surgery is delayed or not possible, medical therapy with diazoxide (200-600 mg daily in divided doses) can inhibit insulin release, and other medications like octreotide (starting at 50 mcg subcutaneously 2-3 times daily) or everolimus (10 mg daily) can be considered for refractory cases 1. However, somatostatin analogues like octreotide or lanreotide should be used with caution in patients with insulinoma, as they can worsen hypoglycemia 1.
Surgical Management
The primary treatment for exophytic or peripheral insulinomas is enucleation, which can be performed laparoscopically for localized solitary tumors within the body and tail of the pancreas 1. If enucleation is not possible, pancreatoduodenectomy or distal pancreatectomy with preservation of the spleen may be considered. Laparoscopic procedures are safe for patients with insulinomas and may be associated with shorter hospital stays 1.
Malignant Insulinomas
For malignant insulinomas, which represent about 10% of cases, additional treatments may include chemotherapy, targeted therapies, or peptide receptor radionuclide therapy. Insulinomas cause symptoms through autonomous insulin secretion unrelated to blood glucose levels, leading to neuroglycopenic symptoms like confusion, visual disturbances, and seizures, as well as autonomic symptoms including sweating, tremors, and palpitations 1.
From the FDA Drug Label
Diazoxide Oral Suspension is indicated for the management of hypoglycemia due to hyperinsulinism associated with the following conditions: ... islet cell adenoma,
- Insulinoma is another term for islet cell adenoma.
- The drug label indicates that diazoxide is used for the management of hypoglycemia due to hyperinsulinism associated with islet cell adenoma.
- Therefore, diazoxide can be used in the management of insulinoma (islet cell adenoma) when it causes hypoglycemia due to hyperinsulinism 2.
From the Research
Definition and Pathophysiology of Insulinoma
- Insulinoma is a rare neuroendocrine tumor that causes oversecretion of insulin, leading to symptoms of hypoglycemia 3
- It is the most common pancreatic neuroendocrine tumor (NET) and is usually benign and solitary 3, 4
Diagnosis of Insulinoma
- Diagnosis is confirmed by a supervised fast, and early detection is important 3
- A factory-calibrated continuous glucose monitoring (CGM) system can be useful for evaluating the course of medical treatment, monitoring hypoglycemic episodes, and detecting unconscious hypoglycemia 5
Management of Insulinoma
- Surgical management is considered the only curative method, with tumor enucleation being the procedure of choice when technically feasible 6, 3
- Medical treatment includes pharmacotherapy such as diazoxide, somatostatin analogs, and mTOR inhibitor - everolimus 6, 5
- Conservative treatment with drugs targeting insulin-induced hypoglycemia, non-operative invasive procedures, and curative open or laparoscopic tumor resection are also available options 4
Treatment of Hypoglycemia in Insulinoma
- Hypoglycemia symptoms are frequently pervasive and disabling, with many patients showing impaired hypoglycemia awareness that can lead to life-threatening severe hypoglycemia 7
- A stepwise algorithm for the management of hypoglycemia, stratified by localized versus metastatic disease, can be proposed 7
- Nutritional management of hypoglycemia, including the use of cornstarch products and artificial nutrition, can also be considered 7