Osteogenesis induction is driven by Wnt-dependent, NOTCH- and BMP4/TGFβ-signaling cascades, and the BMP4/TGFβ-signaling axis is crucial for osteogenesis [43,44,45]; however, SMAD4 expression during osteogenesis was found to be equal in the NGT and T2DM groups. Here, BMP4 is linked to type 2 diabetes mellitus.