Schematic illustrating the association between high glucose, miR-203-3p and the BMP/Smad1 pathway. High glucose results in high expression of miR-203-3p, which represses osteogenesis by i) targeting Smad1 to directly attenuate the BMP/Smads pathway or promote the TGF-β/activin pathway, which has an inhibitory role in osteoblast differentiation, by indirectly reducing Smad1 and Smad2/3 competition for Smad4 and the two pathways act synergistically; ii) targeting Runx2 to attenuate the synergistic effect on the BMP/Smads pathway or downregulating the downstream transcription of osteogenic genes. BMP, bone morphogenetic protein; TGF, transforming growth factor; miR, microRNA; Runx2, runt-related transcription factor 2; OC, osteocalcin; P, phosphate; Col1a1, collagen type 1 α 1.