Insulinoma is the most common functioning tumor of-

Beta-cell tumours or insulinomas are the most common of pancreatic endocrine neoplasms . It may produce sufficient insulin to induce clinically significant hypoglycemia. Clinical picture is dominated by hypoglycemic episodes.,which occurs if blood glucose level falls below 50 mg /DL of serum. Clinical manifestations are confusion,stupor and loss of consciousness. (Ref:ROBBINS Textbook of pathology) ref img