FGF21 and pancreatic insulinoma: Furthermore, the plasma concentrations of FGF21 in patients with insulinoma were significantly reduced (before surgery, 381.36 ± 107.12 pg/mL; after surgery, 254.80 ± 64.10 pg/mL) when blood glucose improved after surgery (before surgery, 3.35 ± 0.42 mmol/L; after surgery, 5.64 ± 0.16 mmol/L) (all P < 0.05; Fig. 1).