INS and type 2 diabetes mellitus: Secondly, in a large-scale, 10-year prospective study of T2DM patients (the METSIM study), it was observed that vitamin D, branched-chain amino acids, low-density cholesterol, triglycerides, proinsulin levels, fatty acids, glycerol, mannose, glycoprotein acetyl (GlycA), and acetyl acetate are associated with an increased risk of T2DM and also serve as T2DM biomarkers (27, 28).