FGF1 and type 2 diabetes mellitus: In comparison, the axonal demyelination was largely alleviated in the T2DM + aFGF group, which was also confirmed by quantifying the proportion of demyelinated axons and analyzing the G-ratio (T2DM + aFGF vs. T2DM: P < 0.01 for abnormal myelin and P < 0.05 for G-ratio; Fig. 2d and e).