Additionally, in the BM of T2DM-N and T2DM-NI patients, both PGP9.5-positive and SP-positive nerve fibres showed a marked increase in diameter (Fig. 1c, ANOVA p < 0.0001 and p < 0.01, respectively), as well as vacuolisation and infiltration with CD68-positive macrophages (Fig. 1d). Here, CD68 is linked to type 2 diabetes mellitus.