What Is Insulinoma?

  • 1st Revision: Chloe Vilenstein


Insulinomas are growths that occur in the pancreas. Insulinomas can be non-cancerous (benign) or cancerous (malignant) and cause disruption to the normal function of the pancreas.1 

The pancreas is an important organ of the digestive and endocrine systems. Its endocrine function is to produce hormones such as insulin and glucagon responsible for controlling blood sugar levels. Pancreatic cells produce more insulin when blood glucose levels increase, for example, after a meal, whereas more glucagon is produced when blood glucose levels are low, for example, during fasting.2

An insulinoma affects the production of insulina and glucagon leading to the abnormal control of blood sugar levels - the tumour causes the pancreas to secrete a higher than normal amount of insulin. This leaves patients in a state called hypoglycemia (low blood sugar) which causes a host of unpleasant, potentially dangerous symptoms.2 

Most insulinomas are treatable with either medication, surgery or both.Your doctor will recommend the best course of action based on the stage of the tumour. Although they are rarely cancerous, it is still important to get diagnosed and treated to avoid worsening health.1 

Stages of insulinoma

Most insulinomas are non-cancerous (benign) and appear as a singular, removable tumour. However, around one tenth of insulinoma cases turn out to be cancerous (malignant) and/or grow to cause many masses in or around the pancreas.

Cancer Research UK looks at three defining features to stage an insulinoma tumour including: 

  1. How large the tumour is
  2. If the tumour has spread to the lymph nodes 
  3. If the tumour has spread to other organs like the liver3

Insulinomas can grow as big as 4 cm, however, most tumours grow no bigger than 2 cm. The larger the tumour is and the more it has spread (metastasized), the more advanced the stage of insulinoma.1 

Causes of insulinoma

The root cause of insulinoma is often unknown. However, there are certain conditions that can predispose you to the disease.

These include:

Signs and symptoms of insulinoma

Insulinoma causes you to have low blood sugar levels also called hypoglycaemia and comparatively high blood insulin levels also called hyperinsulinemia

Physical manifestations of low blood sugar and high blood insulin include: 

  • Profuse sweating 
  • Shaking 
  • Rapid heartbeat1

Low blood sugar can also cause distressing emotional symptoms like extreme mood swings, unusual behaviour and mental fog.1

These symptoms will also appear in episodes rather than as a constant state. Episodes can happen before or after eating and after doing strenuous activity.1

Because these symptoms mirror that of other mental health conditions, hypoglycemia due to insulinoma can often be misdiagnosed.5 

Management and treatment for insulinoma

Most insulinomas are treatable by surgery. To locate a tumour doctors will either palpate over the affected area or use an imaging device such as an ultrasound. Your doctor will also have to determine whether you are a suitable candidate for surgery and how much of the pancreas should be removed.6

Tumours are removed using laparoscopy or keyhole surgery - a less invasive procedure than open surgery. During the procedure, the surgeon will remove a predetermined amount of pancreatic tissue containing the insulinoma.Doctors aim to remove as little healthy pancreatic tissue as possible to leave patients with some pancreatic function after the insulinoma has been removed.6

However, surgery may not be an option for everyone. For example, if you have multiple insulinoma tumours or tumours that have spread outside of the pancreas. Patients who cannot receive surgery will be given an alternative method to control their blood glucose levels and minimise their symptoms - usually medication such as octreotide.1 

If you receive surgery, your doctor will prescribe you medication to replace pancreatic enzymes and insulin due to the reduced postoperative pancreatic function you are likely to experience. It will also be necessary to make adjustments to your diet - you will need to switch to a low fat, unprocessed diet in favour of fresh fruits and vegetables and plenty of protein.2 

You may also want to try natural medicine such as dandelion root as this can help support pancreatic function. However, you should always consult your doctor before taking any new medication. You should especially consult your doctor before combining herbal remedies with any prescription medication you are already taking.2 

Diagnosis of insulinoma

Your doctor should use a combined approach to test you for insulinoma. They may palpate over the area where the pancreas is situated to feel for a tumour. Palpation can also be used to determine where the tumour is before it is surgically removed. 

Your GP should also perform a blood test (you will usually be asked to fast beforehand). Your blood will then be analysed for certain markers of insulinoma. These include:

  • Low blood glucose levels
  • High blood insulin levels 
  • No insulin antibodies circulating in the bloodstream 

Identifying a pancreatic tumour can also be done through computerised tomography (CT) scan or magnetic resonance imaging (MRI)  but they may not always be completely effective depending on the stage of insulinoma and the individual patient.1 

Risk factors

Risk factors for developing insulinoma include:

  • Being a smoker 
  • Having diabetes 
  • Being extremely overweight 
  • Having pancreatitis 
  • Inheriting predisposing genes/genetic condition2


If insulinomas are not promptly diagnosed, some complications with symptoms and treatment can arise. 

Serious symptomatic states of insulinoma include:

  • Abnormal vision
  • Seizures 
  • Coma1

Cancerous insulinomas are also more difficult to treat and usually reduce life expectancy if surgery cannot be performed. Metastasis of a cancerous insulinoma to the liver may also lead to more invasive treatments being needed such as chemotherapy, partial removal of the liver or liver transplantation.1


How can I prevent insulinoma

Because the cause of insulinoma is relatively unknown and/or due to uncontrollable genetic factors, it cannot be completely prevented by any one measure.4

However, there are some things you can do to assist the functioning of your pancreas, especially if you possess one or more of the risk factors of insulinoma. A healthy diet is one of main ways conditions like diabetes, obesity, and pancreatitis are managed - all of which can overwork your pancreas and predispose you to pancreatic disorders like insulinoma.2

Preventative dietary adjustments you can make include:

  • Reducing your sugar intake
  • Reducing your intake of processed and fatty foods
  • Consuming more ‘healthy fat’ for example, unsaturated plant-based fats like coconut oil and olive oil
  • Swapping a high consumption of meat with plenty of plant-based protein sources such as beans
  • Eating fruits and vegetables rich in antioxidants such as leafy greens, blueberries and sweet potatoes.
  • Eating various foods or taking supplements containing essential dietary vitamins and minerals to avoid deficiencies (like vitamin D and folic acid)
  • Eating regular, smaller-portioned meals everyday
  • Boiling and steaming your food instead of frying2

How common is insulinoma

Insulinoma is thought to occur in less than 1% of the population as it is a rare tumour.1 

People assigned female at birth (AFAB) and the elderly are more likely to present with insulinoma.5 

When should I see a doctor

If you are struggling with any of the physical and/or mental symptoms described above you should consult your doctor. Whether the cause of your symptoms is insulinoma or another condition, it is important to receive a diagnosis to be able to get the proper treatment and avoid any complications.


If you experience hypoglycemia (low blood sugar) and its accompanying symptoms, it is important to talk to your doctor to receive a diagnosis. If your doctor suspects insulinoma theywill most likely perform tests and scans to confirm the site of the tumour and decide whether surgery is a viable treatment option. It is important to treat insulinoma promptly as the tumour may grow and spread throughout the body if it is not removed from the pancreas. There are additional medication options to help control your blood sugar and reduce the severity of your hypoglycemic symptoms and it is also recommended that you take care of your digestive health through dietary modification. 

You also shouldnot overlook your mental health while dealing with poor physical health.Your doctor should always be available to talk through any concerns you may have about either and your family, friends and any school or workplace should be informed of your condition so they can support you through your diagnosis and treatment. 


  1. Okabayashi T, Shima Y, Sumiyoshi T, Kozuki A, Ito S, Ogawa Y, et al. Diagnosis and management of insulinoma. World J Gastroenterol [Internet]. 2013 Feb 14 [cited 2023 Apr 28];19(6):829–37. Available from: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3574879/ 
  2. Karpińska M, Czauderna M. Pancreas—its functions, disorders, and physiological impact on the mammals’ organism. Front Physiol [Internet]. 2022 Mar 30 [cited 2023 Apr 28];13:807632. Available from: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9005876/ 
  3. Stages of pancreatic NETs [Internet]. [cited 2023 Apr 28]. Available from: https://www.cancerresearchuk.org/about-cancer/neuroendocrine-tumours-nets/pancreatic-nets/stages-grades/stages 
  4. Insulinoma [Internet]. 2021 [cited 2023 Apr 28]. Available from: https://www.hopkinsmedicine.org/health/conditions-and-diseases/insulinoma 
  5. Service FJ, Dale AJ, Elveback LR, Jiang NS. Insulinoma: clinical and diagnostic features of 60 consecutive cases. Mayo Clin Proc. 1976 Jul 1;51(7):417–29.
  6. 6. Norton JA. Intraoperative methods to stage and localize pancreatic and duodenal tumors. Annals of Oncology [Internet]. 1999 Jan 1 [cited 2023 Apr 28];10:S182–4. Available from: https://www.sciencedirect.com/science/article/pii/S092375342031139X 
This content is purely informational and isn’t medical guidance. It shouldn’t replace professional medical counsel. Always consult your physician regarding treatment risks and benefits. See our editorial standards for more details.

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Amy Murtagh

BSc Veterinary Bioscience - Bachelors of Science, University of Glasgow

Amy is a recent graduate from Glasgow's School of Biodiversity, One Health and Veterinary Medicine with a particular interest in science communication in these subject areas.

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