Islet Cell Tumor: Symptoms and Signs

Approved by the Cancer.Net Editorial Board, 05/2014

ON THIS PAGE: You will find out more about body changes and other things that can signal a problem that may need medical care. To see other pages, use the menu on the side of your screen.

People with an islet cell tumor may experience the following symptoms or signs. Sometimes, people with an islet cell tumor do not show any of these symptoms. Or, these symptoms may be caused by a medical condition that is not a tumor.   


  • Ulcers caused by too much stomach acid
  • Diarrhea


  • Hypoglycemia, which causes fatigue, nervousness and shakiness, dizziness or light-headedness, seizures, and fainting episodes
  • Confusion


  • Hyperglycemia, which causes frequent urination, increased thirst, and increased hunger
  • Rash that spreads on the face, abdomen, or lower extremities


  • Watery diarrhea
  • Too little potassium in the blood, which can cause an irregular heartbeat, muscle cramping and weakness, and decreased reflexes
  • Too little acid in the stomach, which can cause digestive problems and poor absorption of vitamins and nutrients
  • Flushing or redness of the face, neck, or chest
  • Fatigue
  • Nausea


  • Type 2 diabetes, sometimes called adult-onset diabetes
  • Gallstones
  • Steatorrhea, a condition where the body cannot absorb fat, causing oily and loose stools with a particularly bad odor
  • Diarrhea
  • Weight loss
  • Too little hydrochloric acid in the stomach, which can cause digestive problems and poor absorption of vitamins and nutrients

Other symptoms

  • Abdominal pain
  • Jaundice, yellowing of the skin and whites of the eyes
  • Vomiting blood
  • Sweating
  • Rapid heart rate
  • Anxiety
  • Headache
  • Convulsions
  • Loss of consciousness
  • Clouding of vision
  • Unexplained weight gain or loss
  • Inflamed mouth and tongue
  • A mass or lump in the abdomen

If you are concerned about one or more of the symptoms or signs on this list, please talk with your doctor. Your doctor will ask how long and how often you’ve been experiencing the symptom(s), in addition to other questions. This is to help find out the cause of the problem, called a diagnosis.

If a tumor is diagnosed, relieving symptoms remains an important part of your care and treatment. This may also be called symptom management, palliative care, or supportive care. Be sure to talk with your health care team about symptoms you experience, including any new symptoms or a change in symptoms.

The next section helps explain what tests and scans may be needed to learn more about the cause of the symptoms. Use the menu on the side of your screen to select Diagnosis, or you can select another section, to continue reading this guide.