Insulinoma Symptoms
Why symptoms happen
An insulinoma can release insulin when blood glucose is already low, causing hypoglycaemia, or a hypo.
Possible symptoms
Sweating, hunger, weakness or a racing heartbeat.
Confusion, irritability or difficulty thinking clearly as the brain receives too little glucose.
Temporary problems with speech or movement.
In severe cases, seizures (fits) or unconsciousness.
Timing and warning signs
Episodes often occur when you have not eaten, including overnight, but sometimes follow meals. Some people gain weight.
Repeated hypos can make warning signs less noticeable. This is called hypoglycaemia unawareness.
Getting a diagnosis
Symptoms alone cannot confirm an insulinoma. These symptoms have other causes. Doctors check whether symptoms coincide with measured low blood glucose and improve after carbohydrate: Whipple’s triad. Further blood tests investigate the cause.
Read how an insulinoma is diagnosed.
When to get urgent help
Call 999 if someone with suspected severe low blood glucose is unconscious or is not responding normally. Do not give food or drink to someone who cannot swallow safely. Stay with them.
This emergency advice is based on NHS guidance on hypoglycaemia.
Full reference
Hofland J, Falconi M, Christ E, Castaño JP, Faggiano A, Lamarca A, Perren A, Petrucci S, Prasad V, Ruszniewski P, Thirlwell C, Vullierme MP, Welin S, Bartsch DK. European Neuroendocrine Tumor Society 2023 guidance paper for functioning pancreatic neuroendocrine tumour syndromes. Journal of Neuroendocrinology. 2023;35(8):e13318. Question 1. https://doi.org/10.1111/jne.13318
Read the ENETS guidance (PDF).
Updated 27 September 2026.