Type 1 diabetes (T1D) is a chronic autoimmune condition characterized by immune-mediated destruction of pancreatic β-cells, leading to absolute insulin deficiency. This chapter explores the complex pathogenesis of T1D and its association with other autoimmune disorders such as Hashimoto’s thyroiditis and celiac disease. Accurate diagnosis through clinical evaluation and laboratory testing is critical for timely intervention. Management encompasses both acute and long-term strategies. Acute care focuses on diabetic ketoacidosis (DKA) and includes fluid resuscitation, insulin therapy, and electrolyte correction. Long-term management revolves around individualized insulin regimens, lifestyle modification, nutritional counseling, exercise, and psychosocial support. Emerging therapies such as immunomodulatory agents (e.g., teplizumab), β-cell replacement, and artificial pancreas systems offer promising advances. The chapter also reviews complications including acute issues like DKA and hypoglycemia, as well as chronic microvascular and macrovascular complications. With early diagnosis and modern intensive management, individuals with T1D can achieve improved outcomes and quality of life. A proactive, multidisciplinary approach remains essential for optimizing prognosis.