What is an insulinoma?
Insulinoma is a rare tumor of the pancreas. It is made up of cells called islet beta cells, which produce insulin in the pancreas and regulate blood sugar. In general, your pancreas makes more insulin when your blood sugar is high, and when your blood sugar is low. Insulinoma produces insulin at all times, even when your blood sugar is very low.
You may hear of an insulinoma called a “neuroendocrine tumor” because it begins in specific cells in your body called neuroendocrine cells. These tumors are usually small (less than an inch) and most are not cancerous. In most cases, surgery will cure them.
An insulinoma is a rare tumor of the beta cells in the pancreas that results in an excessive amount of insulin being produced. As insulinomas produce insulin, they can cause hypoglycemia and lead to dangerously low blood sugar levels. They generally occur in people between the ages of 40 and 60.
Insulinomas can be a cause of diabetes if the treatment of this disease requires a significant amount of the pancreas to be removed. 90 per cent of insulinomas are benign (non-cancerous), but most of the time these tumors will need to be removed by surgery. 10 per cent of people will have more than one tumor, while in one out of 10 cases, the tumor will spread to another body part.
How is insulinoma related to diabetes?
Secondary diabetes is caused by insulinomas if all or a substantial amount of the pancreas is removed because insulin is no longer being produced. It can cause hypoglycemia, and people with diabetes are more likely to develop hypoglycemia due to medications such as insulin, sulfonylureas, and glinides. However, research suggests that insulinomas are rare in people with prediabetes.
The link between diabetes mellitus and insulinomas of the pancreas is unclear. However, they concluded that when a diabetic patient using insulin experiences a significant reduction in insulin requirements, insulinomas should be considered as a cause. Edemas and others have suggested that insulinomas may coexist with diabetes mellitus, but Muhammad Fouad Hamid and others report that this event is very rare.
Symptoms of insulinoma
People with this disease do not always have noticeable symptoms. When symptoms do occur, they can vary depending on the severity of the condition.
- Double vision or blurred vision
- Anxiety and irritability
- Humour changes
- Sudden weight gain
The most serious symptoms of insulinoma affect the brain. They also affect the adrenal glands, which regulate the stress response and heart rate. Occasionally there are symptoms of epilepsy, a neurological disorder that causes seizures. Symptoms seen in more severe cases of this disease may include:
- Fits or convulsions
- Fast heart rate (more than 95 beats per minute)
- Difficult to focus
- Loss of consciousness or coma
In some cases, insulinomas become larger and spread to other parts of the body. When this happens, you may experience the following symptoms:
- Abdominal pain
- Back pain
- Jaundice or yellowing of the skin and eyes
Causes and risk factors
It is not clear why some people develop insulinomas. Women are slightly more likely to have them than men. Most of the people are between 40 and 60 years old. If you have certain genetic conditions, you are more likely to have an insulinoma, including:
- Multiple endocrine neoplasia type 1: When tumors grow in the hormone-producing glands
- Von Hippel-Lindau syndrome: When tumors and cysts grow in many organs of the body
- Neurofibromatosis type 1: Non-cancerous tumors of the nerves and skin
- Tuberous sclerosis: Non-cancerous tumors that grow in your brain, eyes, heart, kidneys, skin, and lungs.
Insulinomas are very rare. They are very small and are less than 2 cm in diameter. Only 10% of these tumors are cancerous. Cancerous tumors are more common in people with type 1 multiple endocrine neoplasia. It is an inherited disease that causes tumors in one or more hormone glands. The risk of insulinoma is also higher in people with Von Hippel-Lindau syndrome. This inherited condition causes tumors and cysts to form throughout the body.
Doctors have a hard time diagnosing this disease. Its symptoms are similar to other common health problems. It will take a while before your doctor finds it.
They will do tests like:
Blood tests and suppression tests: To find out if you have an insulinoma, your doctor will test your blood sugar, insulin, C-peptide, and proinsulin during a 72-hour rest period.
- You may have symptoms of low blood sugar, especially after not eating or exercising a lot.
- When you have these symptoms, your blood sugar is low
- Once your blood sugar level goes up, your symptoms will go away
To do this, they will see what happens to your blood sugar level after you fast for a day or two. At this point, you must be in the hospital and cannot eat or drink anything but water. The doctor will test your blood to see if you have low blood sugar and high insulin levels.
Imaging tests: You can also get an imaging test like a CT scan, ultrasound, or MRI so your doctor can see where the tumor is.
How is insulinoma treated?
Surgical removal of the tumor is the best treatment for this disease. If there is more than one tumor, even a small part of the pancreas can be removed. It usually cures the condition. Various surgeries may be done to remove the insulinoma. The location and number of tumors determine which surgery will be used.
Laparoscopic surgery is the preferred option if there is a small pancreatic tumor. This is a minimally invasive and low-risk approach. During laparoscopic surgery, your surgeon will make several small incisions in your abdomen and insert the laparoscope through the incisions. The laparoscope is a long, thin tube with a high-intensity light and a high-resolution camera on the front. The camera displays images on the screen, allowing the surgeon to look inside your abdomen and guide the instruments. When it is found, it is removed.
If there are multiple insulinomas, some part of the pancreas needs to be removed. Sometimes even part of the stomach or liver can be removed. In rare cases, removing the cancer may not cure the condition. This generally applies when the tumors are cancerous. Cancer Insulinoma Treatments:
- Radiofrequency ablation, which uses radio waves to kill cancer cells in the body.
- Cryotherapy, which involves the use of extreme cold to destroy cancer cells.
- Chemotherapy, which is an aggressive form of chemotherapy that helps kill cancer cells.
If surgery is not effective, your doctor may prescribe medication to control blood sugar levels.
Complications of insulinoma
Most of the time, surgery cures this disease. There may be side effects or complications after surgery, including:
- If your surgeon removes most of the pancreas, high blood sugar (diabetes)
- Pancreatic fistula
- Low digestive enzymes
If your disease is cancer, problems may include:
- Blood sugar is low if cancer has spread to the liver.