A 12-year-old girl is brought to her pediatrician for evaluation of fatigue, weight loss, bedwetting, and extreme thirst. She had been healthy with no significant past medical history until 2 weeks ago when she started exhibiting these symptoms. The physical examination is notable for a fatigued girl with dry mucous membranes. Her weight is 5 kg less than at her well child examination 5 months before. Laboratory studies show a random blood glucose of 351 mg/dL, a hemoglobin A1C of 11.4%, and metabolic acidosis. Her urine is positive for ketones. What is the final diagnosis?.