An insulinoma is a small tumor in the pancreas that may lead to low blood sugar levels, or hypoglycemia. Surgical removal is the usual treatment, after which a person should make a full recovery.

Most insulinoma tumors are small and noncancerous. However, some might be cancerous.

In this article, learn more about insulinoma tumors, including their symptoms, possible causes, and treatment options.

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The pancreas is an endocrine organ with various roles, including creating insulin, which allows cells to absorb glucose from the blood.

The pancreas also produces other hormones and enzymes that help break down food proteins and fats for energy. It also regulates insulin levels and maintains optimum blood sugar.

Having either low or high blood sugar can lead to serious health problems. Normally, if a person’s blood sugar becomes too low, the pancreas stops creating insulin.

However, an insulinoma tumor will continue to produce insulin regardless of the body’s blood sugar levels. This may result in hypoglycemia.

Insulinoma tumors can be difficult to diagnose. However, after a doctor has confirmed a diagnosis, surgical removal may resolve the symptoms and allow the person to recover.

In some cases, other or additional treatments may be necessary.

Insulinoma tumors will not always cause symptoms, especially when they are small or in the earliest stages.

If symptoms do appear, they can range from mild to severe, and they may appear as a result of low blood sugar.

Mild symptoms may include:

  • confusion
  • weakness
  • sweating
  • a rapid heartbeat

A person may also experience other symptoms, such as headaches, blurry vision, forgetfulness, or persistent hunger.

In more severe cases, low blood sugar from insulin overproduction may cause a person to pass out or go into a coma.

There is no defined cause of insulinoma tumors, and healthcare professionals do not yet know why they spontaneously appear.

Some cases may occur due to rare inherited conditions, such as multiple endocrine neoplasia type 1 (MEN1).

One article notes that MEN1 may contribute to the development of insulinoma tumors in about 6% to 7.6% of cases.

Insulinoma tumors are rare. In fact, according to some research, they occur in about one to four cases per million each year.

The following sections look at some risk factors for the condition.


The median age for diagnosis is 47–50 years old.


Some genetic conditions may increase a person’s chance of developing an insulinoma tumor.

For example, having a family history of endocrine disorders may prompt doctors to consider MEN1. The National Institute of Diabetes and Digestive and Kidney Diseases notes that MEN1 symptoms appear equally in both males and females and may start appearing in their 20s.

Healthcare professionals may also consider the following conditions as possible risk factors for the development of insulinoma tumors:


Additionally, sex seems to play a role, with more females than males developing the condition.

Diagnosing insulinoma is challenging and can take time. Some research notes that doctors achieve a correct diagnosis within 5 years of a person experiencing their first symptom in about 53% of cases.

They may have difficulty confirming a correct diagnosis because the symptoms can appear before tumor detection or because they may appear similar to those of other conditions.

Diagnosis typically occurs in two parts. Healthcare professionals will initially complete a physical check, then they will administer tests to check for insulinoma.

Learn more about diagnosis in the sections below.

The Whipple triad

A set of factors called the Whipple triad may help doctors home in on a diagnosis of insulinoma by helping them diagnose hypoglycemia.

The three factors are:

  • fasting low blood sugar
  • symptoms of low blood sugar
  • relief from symptoms after administration of glucose

Although fasting glucose levels alone are not enough for diagnosis, they may provide an indication of the condition. In fact, some research has found that fasting low blood sugar levels occur in 73% of people with the condition.

Glucose levels

A doctor may ask a person to complete a 72-hour fast to enable them to test their glucose levels.

Multiple tests of glucose levels after eating may also help doctors identify how their body responds to factors that affect blood sugar.

Imaging tests

After establishing a diagnosis of an insulinoma tumor, doctors use imaging tests such as CT and MRI scans to help locate it.

If the tumor is difficult to find or the doctor cannot find it using these imaging tests, they may recommend more invasive procedures, such as an endoscopic ultrasound. This procedure involves sending a small tube through the mouth to the digestive tract and firing small sound waves into the tissues to get a detailed image.

Invasive imaging tests such as endoscopic ultrasound scans may be more sensitive and accurate than CT or MRI scans for pancreatic tumors.

Following diagnosis, a doctor can prescribe treatment.

Treatment for an insulinoma tumor may vary based on factors such as the size and location of the tumor and any possible complications. A healthcare professional may consider surgical removal of the tumor to be the best option.

A single insulinoma with no known source may be curable by surgically removing it.

If the tumor appears in a cluster or involves a larger part of the pancreas, the doctor may also recommend removing surrounding tissue from the pancreas.


Depending on the size and severity of the insulinoma tumor, the doctor may recommend different surgeries or treatment options.

One option is laparoscopic surgery. This type of surgery may be useful for single small tumors.

A surgeon will make several small incisions in the abdomen, inserting narrow tubes that include instruments and a camera. The resulting images will show on a screen, allowing the healthcare professionals to guide the tools and perform the surgery.

After finding the tumor, the surgeon will incise and remove it. If the surrounding tissue is involved or there are multiple tumors, they may need to remove part of the pancreas. If the tumor has spread or other areas are involved, they may remove these tumors or tissues as well.

Removing the tumor typically cures the condition and allows the person to recover. According to one article, 87.5% of people experience no more symptoms after successful surgical removal.

Other treatments

People with malignant tumors or conditions such as MEN1 may have a higher rate of unsuccessful surgery or recurrence, which may mean that other treatment options are necessary.

Sometimes, a person may not be eligible for surgery. In other, rare cases — such as when the tumor is malignant — symptoms may continue after surgery.

Other treatment options before or after surgery may include:

About 60% of people become symptom-free when using the drug diazoxide. However, if symptoms persist after surgery, a doctor may continue prescribing drugs to treat low blood sugar.

Insulinoma is a rare type of tumor that appears in the pancreas and creates more insulin than the body needs. Diagnosis can take time and require multiple tests.

Surgery may be a treatment option, along with drugs, chemotherapy, and cryotherapy.

Factors that may affect recovery include malignancy, recurrence, underlying conditions, and complications from surgery.

Anyone who is experiencing symptoms of insulinoma or low blood sugar should contact a doctor for diagnosis.