INS and type 2 diabetes mellitus: When acting as regulators, metabolites have an impact on the pathogenesis of T2DM in at least the following aspects: (1) Metabolites can regulate the downstream signaling pathway of insulin and directly affect insulin sensitivity; (2) Accumulation of harmful metabolic intermediates; (3) Cause organelle dysfunction; (4) Directly or indirectly mediates the inflammatory response of target tissues.