ABSTRACT:
Diabetes Mellitus (DM) represents a complex group of metabolic disorders characterized by chronic hyperglycemia resulting from defects in insulin secretion, insulin action, or both. This paper provides a comprehensive overview of the primary classifications—Type 1, Type 2, and Gestational Diabetes—detailing their distinct etiological pathways.The pathophysiology of Type 1 Diabetes is explored through the lens of autoimmune-mediated destruction of pancreatic $\beta$-cells, leading to absolute insulin deficiency. Conversely, the discussion on Type 2 Diabetes focuses on the progressive combination of insulin resistance in peripheral tissues and a compensatory, yet ultimately failing, insulin secretory response. We further examine the molecular mechanisms involving inflammatory cytokines, oxidative stress, and the role of genetics and lifestyle in disease progression. By synthesizing current understanding of these mechanisms, this paper underscores the importance of differentiated diagnostic and therapeutic approaches to mitigate long-term microvascular and macrovascular complications