INS and pancreatic insulinoma: Fasting serum insulin concentrations were significantly higher in 74 patients with insulinoma than in 28 controls (median 18.9 μIU/mL, range 2.8-300 μIU/mL vs. median 3.9 μIU/mL, range 2.2-10.7 μIU/mL, P <0.0001; Supplementary Figure 1).