BDNF and type 2 diabetes mellitus: Interestingly, at all levels of pairwise comparisons of differential expression among the three groups, several signaling cascades are related to insulin signaling or T2D but are not limited to, e.g., the MAPK signaling cascade, the mTOR signaling cascade, TLR signaling, p53 signaling, WNT signaling, and neurotrophin signaling pathways.