Normally, the pancreas makes more insulin when your blood sugar is high and less when those levels drop. But when you have an insulinoma, the tumor will keep making insulin even when your blood sugar gets too low.
These tumors are usually small (less than an inch), and almost all of them are not cancer. In most cases, surgery can cure the problem.
Because these tumors make too much insulin, they can cause symptoms of low blood sugar, also known as hypoglycemia. You could have:
Hypoglycemia is common in people with diabetes. It often happens because they took too much of their medicine, missed a meal, or got more exercise than usual, all of which can lower blood sugar. An insulinoma can also cause hypoglycemia when you haven’t eaten in a while, but it can happen at any time.
What Causes an Insulinoma?
It’s not clear why some people get these tumors. Women are slightly more likely to have them than men, and most people get them between ages 40 and 60. You’re also more likely to have an insulinoma if you have certain genetic diseases, including:
- Multiple endocrine neoplasia type 1 -- when tumors grow in glands that produce hormones
- Von Hippel-Lindau syndrome -- when tumors and cysts grow in many organs throughout the body
- Neurofibromatosis type 1 -- noncancerous tumors in the nerves and skin
- Tuberous sclerosis -- noncancerous tumors that grow in organs such as the brain, eyes, heart, kidneys, skin, and lungs
Getting a Diagnosis
It can be tough for doctors to diagnose an insulinoma. Its symptoms are the same as other common health problems. It may take time before your doctor can find it.
To find out if you have an insulinoma, your doctor will need to confirm:
To do that, your doctor will need to watch what happens to your blood sugar after you fast for a day to two. You may need to stay in the hospital during this time, and you won’t be able to eat or drink anything except water. Your doctor will test your blood to see if you have both low blood sugar and a high insulin level.
You may also get an imaging test such as a CT scan so your doctor can see where the tumor is.
The main treatment for an insulinoma is surgery to remove the tumor. Most of the time, that will cure you.
The type of surgery you get depends on the type, size, and location of the tumor. Surgeons can usually remove just the insulinoma from the surface of the pancreas and leave the organ intact.
Sometimes the surgeon may need to remove part of the pancreas connected to the tumor. But this type of surgery is less common.
You might be able to have laparoscopic surgery to remove an insulinoma. In this operation, doctors make several smaller cuts in your body instead of one large one. They use special instruments to do the surgery. That means you’ll have less pain as you heal, stay fewer days in the hospital, and can return to normal life more quickly.
Most people won’t need any more treatment after surgery.
If your doctor thinks surgery won’t work for you, you can try other treatments to manage low blood sugar. You might take medicine and eat smaller meals more often throughout the day.
Cancerous insulinomas are rare, and they need different treatment. If your doctor can’t remove the whole tumor, you may need to take other medicine to prevent low blood sugar. You may also need chemotherapy.