Strategy in the diagnosis of insulinoma.

A simple diagnostic strategy in the diagnosis of insulinoma in adult subjects is proposed based upon the literature and own experiences. It comprises measurement of plasma proinsulin, insulin and C-peptide as well as blood glucose after an overnight fast. When a low or normal proinsulin concentration is found, organic hyperinsulinaemia is very unlikely, while elevated proinsulin, after exclusion of uremia, hepatic cirrhosis, thyreotoxicosis and surreptitious administration of insulin or sulfonylurea drugs, strongly indicates this condition.