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Symptoms of insulinoma

Insulinoma is a type of neuroendocrine tumour (NET) of the pancreas. Its symptoms can be vague. See your GP if you are worried.

Symptoms

Insulinomas make the hormone insulin, which controls the amount of blood sugar in the body. So doctors call them a type of functioning neuroendocrine tumour of the pancreas. 

The most common symptoms of insulinomas are caused by changes in the blood sugar level. You usually have symptoms when your blood sugar is low.

Having low levels of blood sugar can be dangerous if you don’t eat something straight away. You might have fits (seizures) and become unconscious (coma).

Weakness and tiredness

You might feel very tired a lot of the time.

Headaches

Headaches are a common symptom of many illnesses. You should see your doctor if you:

  • have very bad headaches (especially if you wake up every day with a headache)
  • have headaches more and more often
  • have headaches when you didn’t have them before
  • have headaches and sickness together

Problems with your eyes

You might have double vision and blurred vision.

Forgetfulness and confusion

You might forget things more easily and you, or the people that are close to you, may notice that you are confused.

Behaving in a way that isn’t normal for you

The people that are close to you might notice this. 

Hunger and sickness

You might feel that you are hungry all the time. You may also feel or be sick.

Sweating and tremors

You might have a sudden onset of sweating and feel like you are shaking or having tremors.

Palpitations

You may feel that your heart is racing. This can make you feel dizzy, breathless and lightheaded.

Whipple’s triad

The Whipple’s triad is a collection of symptoms that help doctors diagnose an insulinoma. It includes:

  • symptoms of a low blood sugar such as feeling dizzy and sweating
  • a blood sugar level lower than 2.2 mmol per litre of blood
  • feeling better after eating food with a high amount of sugar, or after having a glucose drip

When to see your doctor

You should see your doctor if you have any symptoms that are unusual for you, won’t go away, or are getting worse. Although your symptoms are unlikely to be cancer, it is important to get them checked by a doctor.
Last reviewed: 
11 Jul 2019
  • Suspected cancer: recognition and referral
    National Institute for Health and Care Excellence (NICE), June 2015

  • Diagnosis and management of insulinoma
    T Okabayashi and others
    World Journal of Gastroenterology, 2013. Vol 19, Issue 6, Pages 829-837

  • ENETS Consensus Guidelines Update for the Management of Patients with Functional Pancreatic Neuroendocrine Tumors and Non-Functional Pancreatic Neuroendocrine Tumors
    M Falconi and others
    Neuroendocrinology, 2016. Vol103, Pages 153–171

  • Well-differentiated pancreatic tumor/carcinoma: insulinoma
    W de Herder and others
    Neuroendocrinology, 2006. Vol 84, Pages 183-188 

  • Neuroendocrine gastro-entero-pancreatic tumors: ESMO Clinical Practice Guidelines for diagnosis, treatment and follow up
    K Oberg and others
    Annals of Oncology, 2012. Vol 23, Supplement 76, Pages 124-130

  • Guidelines for the management of gastroenteropancreatic neuroendocrine (including carcinoid) tumours (NETs)
    J K Ramage and others
    BMJ, 2012. Vol 61, Pages 6-32

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