Insulinoma is a type of pancreatic neuroendocrine tumour (pNET) or islet cell tumour where masses of endocrine cells of the pancreas band together to form tumorous growths. These rare tumours chiefly affect the endocrine cells that function by secreting insulin (the hormone that keeps a check on blood sugar (blood glucose) levels from getting too high). Although, approximately 90% of insulinomas are benign tumours (i.e., they don’t spread outside the pancreas), 10% of them might turn malignant tumours (i.e., they may gradually spread outside the pancreas and infect other healthy tissues). Benign insulinomas are usually cured by removing them surgically from the pancreas.

Also Read: Pancreatic Cancer: Causes, Symptoms And Treatment
Insulinomia

Causes

On eating food, the pancreas produces insulin which assists the body in storing the sugar from the food in the form of blood glucose. In a healthy human being, the pancreas usually stops the production of insulin when the sugar has been absorbed by the body and the blood glucose levels have also dropped. This process primarily helps regulate the blood sugar levels and keeps them stable, but it can get disturbed when you develop an insulinoma. An insulinoma causes the healthy endocrine cells to go rogue which then malfunctions and continues to create and secrete insulin even after the blood sugar levels have dropped.

This can lead to a condition medically termed hypoglycemia, which is characterized by low blood sugar levels in the blood. Hypoglycemia is quite dangerous and potentially fatal condition inducing a feeling of unconsciousness, a racing heartbeat and even seizures.

Also Read: Insulin: Structure, Functions, Blood Test, Adverse Effects

Risk Factors

The primary causative factors that increase the risk of insulinomas in people include:

Age: It is usually diagnosed in people within the age group of 40–60

Gender: Insulinomas are more common in females than their male counterparts

Although the exact causative factor of insulinoma is yet unknown, several medical data and pieces of research have led scientists and doctors to associate insulinoma with the following syndromes and conditions:

Neurofibromatosis type 1 (NF1): This condition mainly affects the nervous system and the skin

Tuberous sclerosis complex (TCS): This is a hereditary health anomaly that may cause epilepsy, benign tumours and growths on the skin

Multiple endocrine neoplasia type 1 (MEN1): Another genetic disorder that chiefly affects the endocrine glands and the duodenum (the first part of the small intestine)

Von Hippel-Lindau Syndrome: A type of congenital health aberration which leads to the formation of tumours throughout the body

Symptoms

Insulinomas initially usually do not give rise to noticeable symptoms. When symptoms do appear, they mainly vary from one individual to another depending upon the severity of their condition.

Some people with insulinomas may experience common signs and symptoms as a result of hypoglycemia. Some of the mild symptoms include:

  • Blurred or double vision
  • Lightheadedness
  • Sweating profusely
  • Intense hunger
  • Sudden weight gain
  • Mood changes
  • Anxiety
  • Irritability
  • Confusion
  • Tremors
  • Weakness

In case insulinoma has grown large, it can affect the brain and neural functions. Some of these severe symptoms include:

  • Seizures
  • Difficulty in concentrating
  • Loss of consciousness
  • Racing heartbeat
  • Coma

Diagnosis

If you notice any of the above-mentioned signs and symptoms, do consult a doctor at the earliest to avoid complications or other fatal injuries. The doctor usually does a thorough physical checkup, acknowledges the patient’s family health history and past medical history and conducts the following diagnostics. These include:

Blood Tests: This is done to detect insulin levels, look for hormones that might affect insulin production, the presence of protein molecules that might block the production of insulin and the presence of medications that might induce the pancreas to release more insulin

Imaging Techniques: These include CT scan, PET scan, MRI scan and Ultrasound

Biopsy: To detect whether the insulinoma cells are malignant

Staging Of Insulinoma

The insulinoma cells are often graded to estimate how quickly a pNET-like insulinoma might grow and spread to other healthy tissues:

Grade 1: Also termed low-grade or well-differentiated stage, the cells in this stage appear more like the normal ones and are not multiplying quickly

Grade 2: Termed intermediate-grade or moderately differentiated stage,  the characteristic features of the tumours of this stage fall in between those of low- and high-grade tumours

Grade 3:  Also called high-grade or poorly differentiated stage, tumours in this advanced stage have cells that look very abnormal and are multiplying and spreading rapidly

Treatment

The most preferred treatment option for curing Insulinoma is Surgery where the surgeon completely removes the tumour.

Surgery: The surgical procedure can be done in three ways. This includes Enucleation (removing the insulinoma without cutting into it), Partial pancreatectomy (removing part of the pancreas where insulinoma is located) and Whipple surgery (an invasive surgical technique that is mainly opted for when the tumour has become malignant. In this case, the doctor surgically removes part of the pancreas, gallbladder, part of the stomach, small intestine, bile duct and nearby lymph nodes.)

In case, surgery is not a preferred option, the doctor may suggest combining surgery with medical or nonsurgical treatments. These include:

Peptide Receptor Radionuclide Therapy (PRRT): The PRRT treatment involves injecting a medication into the bloodstream that combines radioactive atoms and amino acids to aim and kill insulinoma cells

Targeted therapy: This technique uses medicines or other substances to ambush cancer cells without injuring the normal ones

Chemotherapy: This therapy uses several types of medications to destroy the malignant cells

Liver-directed therapy: This treatment is usually targeted at tumours in the liver

Diazoxide: This medication helps remedy low blood sugar conditions

Octreotide/lanreotide: This is an analogue version of somatostatin that assists in regulating neuroendocrine tumour (NET) symptoms