Diabetic ketoacidosis is an acute complication of Diabetes Mellitus characterized by hyperglycemia, metabolic acidosis, dehydration, and ketosis, in patients with profound insulin deficiency. It occurs predominantly in patients with type 1 diabetes and is frequently precipitated by infections, insulin withdrawal or undiagnosed type 1 diabetes. The authors review its pathophysiology, diagnostic criteria and treatment options in adults, as well as its complications.