Insulinoma	

Insulinoma (fasting hypoglycaemia) is a rare but important cause of hypoglycaemia and occurs with an incidence of approximately one case per million population per year. Hypoglycaemia and its associated neuroglycopenia are the presenting, and usually only the discernible, abnormalities. Characteristically there is a history, often going back several years, of episodic alterations in consciousness – these last from a few minutes to several hours and occur with increasing frequency and severity. 

See also:
• Imaging in Parathyroid/bone Disease