FGF21 and gestational diabetes: Our finding of a significantly higher plasma FGF21 in the background of essentially similar CSF FGF21 levels leading to a lower CSF/Plasma FGF21 ratio in women with GDM compared to control subjects implies either that there is a deficiency of FGF21 transport across the BBB or that discrepancies in the production and/or metabolism of FGF21 by the central nervous system may explain the differences in CSF/plasma FGF21 ratio between the GDM and control subjects in our study.