Insulinoma is a neuroendocrine tumor of the pancreas that results in the production of excessive insulin.

Neuroendocrine tumors – more precisely known as gastroenteropancreatic neuroendocrine tumors or gastro-entro-pancreatic tumors – are neoplastic growths that attack the interface between the endocrine (hormonal) system and the nervous system.

Growths resulting from insulinomas are typically less than 2cm in size and more than 90% of them are benign (non-cancerous).

Signs and Symptoms

The common symptoms that patients with insulinomas complain about are related to low levels of glucose (sugar) in the blood. This includes tiredness, weakness, tremors, recurrent headache, diplopia (when a single object is perceived as two images), and blurred vision.

When severe hypoglycemia (the state produced by extremely low levels of glucose in the blood) is present, patients may experience seizures, coma, and permanent neurological damage resulting in an array of psychiatric symptoms. A patient suddenly becoming massively obese is another occasional effect of insulinomas.

Diagnosis

Diagnosing an insulinoma requires the simultaneous measurements of glucose and insulin levels in the blood. If glucose levels are low and insulin levels are high, then a diagnosis is confirmed. Following the biochemical analyisis, the tumor must be physically detected in the pancreas.

Due to the small size of these tumors, detection is difficult. CT scans, MRI’s, octreotide scans, and ultrasounds are commonly used to locate insulinomas.

Treatments

Surgical removal of the tumor is the preferred way to treat insulinomas. More than 90% of these growths are benign and will not require any further treatment after the removal. Furthermore, removal of the tumor will cure most patients of the symptoms.

Typically, an enucleation is performed to remove the tumor. This procedure removes only the tumor (most insulinomas occur on the surface of the pancreas) and preserves the surrounding pancreas. Insulinoma recurrence after enucleation is very low.
Pancreatic resection (removal) is a less common treatment of insulinoma.

If the tumor has spread beyond the surface of pancreas and/or if the tumor is malignant, then a partial removal of the pancreas is usually necessary. This procedure is not a commonality since most insulinomas occur exclusively on the surface of the pancreas.

If a patient is not a surgical candidate or has an inoperable tumor, there are medications to aid the body in blocking the excess amounts of insulin excreted from the pancreas.

Prognosis

Nearly all patients with benign tumors can be cured completely with surgerical removal of the tumor and/or part of the pancreas. Patients with multiple tumors will often develop persistent or recurrent hypoglycemia and about two percent of insulinoma patients will develop diabetes mellitus after the surgery.