Alteration of consciousness is a common problem in clinical practice. Many of pathologic and metabolic disorders can decrease the conciousness level, transient or permanently.

Hypolycemia is one of the most common metabolic disorders. Hypoglycemia is a biachemical abnormality, not a disease. An abnormally low glucose concentration can be caused by a number of factors, such as, drug, tumors, altered gastrointestinal anatomy nad, failure of both endoctrine and nonendoctrine tissues.

Although Insulinomas are rare tumors, the correct diagnosis is extremely important. Not only they are usually curable, but also if patients remain undiagnosed for long periods, they may develop, permanent neuropsychiatric sequelas.

In this article, while discussing about clinical presentation of Insulinoma and how to approach it, we represent a patient with proved insulinoma.