Diabetes mellitus is a chronic metabolic disorder marked by persistent hyperglycemia, leading to serious microvascular and macrovascular complications such as diabetic retinopathy (DR), nephropathy (DN), neuropathy (DPN), and cardiovascular disease (CVD). These arise from interconnected mechanisms including oxidative stress, inflammation, AGEs, and endothelial dysfunction. Modern treatment strategies address both underlying pathology and symptoms. Anti-VEGF agents are central to managing DR and DME, with corticosteroids and laser therapy as adjuncts. DN therapy focuses on RAS blockade, tight glycemic and blood pressure control, and early detection through biomarkers. DPN treatment involves glucose regulation, pain management, and experimental therapies targeting oxidative/inflammatory pathways, though clinical efficacy is still emerging. CVD risk is managed through lipid control, antihypertensives, and glucose-lowering agents with heart benefits. A personalized, multidisciplinary approach is essential to reduce complications, enhance life quality, and lower long-term mortality.