If this ratio occurs in a single artery, it is diagnostic of insulinoma; however, if an insulin ratio >2 is measured in multiple arteries, this is diagnostic of nesidioblastosis. The SACST showed an insulin ratio >2 in the proximal splenic artery, gastroduodenal artery (GDA), and proper hepatic artery (PHA), consistent with a diagnosis of nesidioblastosis (Table 1, Figure 1). This evidence concerns the gene INS and pancreatic insulinoma.