Insulin resistance arises from serine phosphorylation of insulin receptor substrate (IRS) proteins mediated by stress kinases such as c-Jun N-terminal kinase (JNK) and IκB kinase-β (IKKβ), compounded by lipotoxic and cytokine-driven signaling defects. Sustained hyperglycemia diverts glucose flux into four classical pathogenic pathways, the polyol pathway, advanced glycation end-product (AGE) formation, protein kinase C (PKC) activation, and hexosamine biosynthesis, each converging on excess reactive oxygen species (ROS) generation. ROS-mediated activation of NF-κB establishes a selfamplifying loop between oxidative stress and chronic low-grade inflammation, further impairing insulin signaling and accelerating vascular injury. Epigenetic changes underlying “metabolic memory” explain why complications may progress despite subsequent glycemic control. Oxidative stress and inflammation are not peripheral bystanders but central, mechanistically interdependent drivers of T2DM pathogenesis and its complications. Early, intensive metabolic control exploits a therapeutic window before metabolic memory is consolidated, underscoring the need for sensitive biomarkers and targeted antioxidant/anti-inflammatory strategies alongside conventional glycemic management.