Diabetes mellitus is a chronic metabolic disorder characterized by elevated blood glucose levels resulting from defects in insulin secretion, insulin action, or both. It is a global health concern affecting over 500 million people worldwide, with rising prevalence due to lifestyle and genetic factors. The condition is broadly categorized into Type 1 diabetes, Type 2 diabetes, gestational diabetes, and other specific types due to genetic or secondary causes. Chronic hyperglycemia in diabetes is associated with long-term damage, dysfunction, and failure of various organs, especially the eyes, kidneys, nerves, heart, and blood vessels. Diagnosis typically involves measuring fasting blood glucose, oral glucose tolerance, or HbA1c levels. Effective diabetes care includes glycemic control, cardiovascular risk management, lifestyle modifications, and regular monitoring for complications. Advances in pharmacotherapy, continuous glucose monitoring (CGM), and digital health tools are transforming diabetes management and patient outcomes. The multifaceted nature of diabetes demands integrated care models, patient education, and early intervention strategies to mitigate its global burden.