Diabetes Mellitus: A Comprehensive Review of Types, Pathophysiology, Complications, and Standards of Care in Diabetes 2025

Diabetes mellitus represents a complex spectrum of metabolic disorders with diverse pathophysiological mechanisms unified by the common endpoint of hyperglycemia. The classification into different types—primarily type 1, type 2, gestational, and various rare forms—reflects the heterogeneity of the disease and necessitates tailored approaches to diagnosis and management. The pathophysiology of diabetes involves intricate interactions between insulin secretion and action, with distinct mechanisms leading to beta cell destruction in type 1 diabetes and the dual defects of insulin resistance and progressive beta cell dysfunction in type 2 diabetes. The complications of diabetes demonstrate the profound impact of chronic hyperglycemia on multiple organ systems through both microvascular and macrovascular damage. The selective vulnerability of certain cell types to hyperglycemia-induced injury explains the pattern of complications affecting the kidneys, eyes, nerves, and cardiovascular system. Understanding the unifying mechanisms and specific metabolic pathways involved in these complications has facilitated the development of targeted preventive and therapeutic strategies.
Recent updates from the 2025 Standards of Care in Diabetes reflect the evolving understanding of the disease and its management, with increasing emphasis on technological solutions, individualized approaches, and comprehensive risk reduction. The reconceptualization of diabetes as part of a broader metabolic dysfunction syndrome represents an important paradigm shift that may lead to more integrated approaches to prevention and treatment. Moving forward, continued research into the pathophysiological mechanisms of diabetes and its complications will be essential for developing novel therapeutic targets and improving outcomes for the growing number of individuals affected by this global health challenge.