Insulinomas are tumors in your pancreas that produce excess insulin. These tumors are very rare and usually do not spread to other parts of your body.
Insulin is a hormone that regulates the amount of sugar in your blood. Insulinomas can cause hypoglycemia, or low blood sugar levels, because they make extra insulin. This can result in a number of symptoms. These include confusion, dizziness or light-headedness, anxiety, sleepiness, shakiness, sweating, weakness, and a rapid heartbeat. If your blood sugar becomes too low, you can pass out and even go into a coma.
Who’s at risk
Few risk factors are associated with insulinomas, although women seem to be more frequently affected than men. Usually, you develop the condition between ages 40 and 60. Some genetic diseases can increase your chance of developing an insulinoma. Adults with multiple endocrine neoplasia, for example, have about a 10 percent chance of getting an insulinoma. This condition may also affect people with von Hippel-Lindau syndrome. This is an inherited disease that causes tumors and cysts throughout your body.
Doctors often mistake insulinomas for other health problems. In fact, the average time between the onset of your symptoms and a diagnosis is about three years. If your doctor suspects the presence of an insulinoma, he or she may admit you to the hospital for several days to monitor your blood sugar and other substances in your blood. You will not be able to eat or drink anything except water during this time. If you have insulinomas, you will probably develop very low blood sugar levels within 48 hours of starting this test.
To confirm an insulinoma, your doctor may also use one or more imaging tests to determine how big your tumor is and where it's located. A CT (computed tomography) scan is a common procedure doctors use to locate insulinomas. However, doctors may obtain a better picture with endoscopic ultrasound. This is an outpatient procedure that uses a miniature ultrasound probe that is passed into the digestive tract to create an image of your pancreas
Most insulinomas are benign, and surgeons can usually remove them. Sometimes the surgeon performs a laparoscopy. He or she makes small incisions and uses specialized instruments including a small internal camera, rather than performing a surgery that requires making long incisions along your abdomen (called a laparotomy). While you are waiting for your surgery, you may stay in the hospital and receive special intravenous solutions to keep you from becoming hypoglycemic.
Some people who undergo surgery to remove an insulinoma may develop a pancreatic fistula. This is an abnormal leaking of fluid from your pancreas. Your doctor may give you medicine and additional fluids to help your fistula heal. Most fistulas close without the need for additional surgery. A rare complication is a recurrence of an insulinoma elsewhere in the pancreas of a smaller missed insulinoma. Another rare complication is Diabetes Mellitus if a large portion of the pancreas needs to be removed.
There are no known ways to prevent insulinomas.
When to call your doctor
If you have insulinomas, you may experience symptoms related only to your hypoglycemia, like sweating, confusion, and double vision. You may notice these symptoms more when you’re hungry or after exercise. If you experience hypoglycemic symptoms several times in one week, consult your doctor promptly.
How to manage or live with the condition
Almost all insulinomas are benign. Removing the tumor cures the condition. Usually, patients do not experience a relapse or recurrence of the symptoms. You are unlikely to develop diabetes unless your surgeon removes a large part of your pancreas.
A small number of insulinomas are malignant. Your surgeon may not be able to entirely remove them. If this happens, you may need to take medications to stave off hypoglycemia. You may also need chemotherapy to help control the size of your tumors.
- Hanrahan, John, MD
- MMI board-certified, academically affiliated clinician