Diabetic ketoacidosis — branching viva

Emergency department: a 5-year-old girl not known to have diabetes is brought in drowsy with a two-week history of drinking and passing urine excessively, now vomiting and breathing deeply with a sweet smell to her breath. Capillary glucose reads high, blood ketones are 5 mmol/L, and a venous gas shows pH 7.05 with a bicarbonate of 5 mmol/L. She is dehydrated but not shocked. The examiner asks: what is your diagnosis and how do you grade it, what is your fluid and insulin plan and in what order, why is her potassium misleading, and what complication must you watch for and how would you treat it — then branches to a pump user with unexplained ketosis, a persisting acidosis with a normalising glucose, and the resolution criteria for transition to subcutaneous insulin.