An insulinoma is a small and rare type of pancreatic tumor. Surgical removal is the standard treatment, although most insulinomas aren’t cancerous or otherwise life threatening.
One of the functions of the pancreas is to produce hormones, like insulin, that control the level of sugar in your bloodstream.
An insulinoma is a tumor that forms in the pancreas and produces an excess amount of insulin.
Normally, the pancreas stops creating insulin when the sugar has been absorbed and your blood sugar drops too low. This process usually keeps your blood sugar levels stable, but it can be disrupted when you develop an insulinoma.
An insulinoma will continue to produce insulin even after your blood sugar drops too low.
This can lead to hypoglycemia, which is characterized by low blood sugar levels. Hypoglycemia is a dangerous and potentially life threatening condition.
Insulinomas are rare. Most are noncancerous and small, measuring less than 2 centimeters in diameter.
However, they usually need to be removed. Once the tumor is surgically removed, complete recovery is very likely.
Insulinomas don’t always cause noticeable symptoms. When symptoms do occur, they can vary depending on the severity of the condition.
Some people with insulinomas may experience symptoms as a result of hypoglycemia.
Mild symptoms include:
- double vision or blurred vision
- dizziness or lightheadedness
- sudden weight gain
- mood changes
- anxiety and irritability
Symptoms that are seen in more serious cases may include:
Symptoms of a metastatic insulinoma
In some cases, insulinomas can get bigger and metastasize (spread) to other parts of the body. When this occurs, you may have the following symptoms:
Metastatic insulinomas are considered malignant, or cancerous.
Doctors don’t know exactly why people get insulinomas. The tumors typically show up without warning.
These tumors are rare.
They tend to affect people assigned female at birth more often than people assigned male at birth. They most commonly develop in people ages 40 to 60 years.
The risk of insulinoma may also be higher for those with Von Hippel-Lindau disease, an inherited condition that causes tumors and cysts to form throughout the body.
Blood tests and imaging tests can help a doctor diagnose an insulinoma.
A doctor will perform a blood test to check your blood sugar and insulin levels. A low blood sugar level with a high insulin level indicates the presence of an insulinoma.
The test can also detect:
- other hormones that affect insulin production
- proteins that block the production of insulin
- medications that cause the pancreas to release more insulin
The doctor may order a fast if the blood test indicates that you have an insulinoma. You won’t be able to eat or drink anything except water during the fast.
These fasting tests have traditionally lasted 72 hours, but recent research has established that 48-hour fasts are also effective.
You’ll stay in the hospital while you fast so the doctor can monitor your blood sugar levels. They’ll measure your blood sugar levels every 4 to 6 hours.
If you have an insulinoma, you’ll likely have very low blood sugar levels within 48 hours of starting the fast.
To confirm the diagnosis, the doctor may perform imaging tests, such as a CT scan or an MRI. These tests help them determine the location and size of the insulinoma.
If the tumor can’t be found using a CT scan or an MRI, they may perform an endoscopic ultrasound.
During an endoscopic ultrasound, the doctor inserts a long, flexible tube (or endoscope) into your mouth and down through the stomach and small intestine. The tube contains an ultrasound probe, which emits sound waves that produce detailed images of your pancreas.
Once the doctor locates the insulinoma, they will take a small sample of tissue for analysis. This tissue sample can be used to determine whether the tumor is cancerous.
The best treatment for an insulinoma is surgical removal of the tumor. If there’s more than one tumor, a small part of the pancreas may also be removed.
The location and number of tumors determine which type of surgery will be used.
Laparoscopic surgery is the preferred option if there’s only one small tumor. This is a low risk, minimally invasive procedure.
During laparoscopic surgery, a surgeon makes several small incisions in your abdomen and inserts a laparoscope through the incisions. This long, thin tube has a high intensity light and a high resolution camera at the front.
The camera will display the images on a screen, allowing the surgeon to see inside your abdomen and guide the instruments. Then the surgeon will find and remove the insulinoma.
If you have multiple insulinomas, part of the pancreas may need to be removed. This typically cures an insulinoma.
Sometimes, part of the stomach or liver may be removed as well.
In rare cases, removing the insulinoma won’t cure it. This is usually the case when the tumors are cancerous.
Treatments for cancerous insulinomas include:
- Radiofrequency ablation: This uses radio waves to kill cancerous cells in the body.
- Cryotherapy: Cryotherapy involves the use of extreme cold to destroy cancerous cells.
- Chemotherapy: Chemotherapy is an aggressive form of chemical drug therapy that helps destroy cancerous cells.
If surgery wasn’t effective, your doctor may also prescribe medications to help you manage your blood sugar levels.
In general, complications are more likely in people with cancerous insulinomas.
This is particularly true when the tumors have spread to other organs. The surgeon may not be able to remove all of the tumors completely. In this case, additional treatment and follow-up care will be necessary.
Keep in mind that insulinomas are rare in general, and only a small percentage of them are cancerous.
The long-term outlook for people with insulinomas is very good if the tumor is removed. After surgery, most people recover completely without complications.
An insulinoma may return in the future, though. Recurrence is more common in people who have multiple tumors.
Doctors don’t know why insulinomas form, so there’s no known way to prevent them.
However, if you develop an insulinoma, you can reduce your risk of hypoglycemia by maintaining a balanced diet. This diet should largely consist of fruits, vegetables, and lean protein.
You can also keep your pancreas healthy by eating less red meat and quitting smoking if you smoke.