A healthy 18-year-old girl presented to a local emergency room with 48 h of abdominal pain and vomiting. A radiological and biochemical diagnosis of moderate acute pancreatitis was made. Bloodwork demonstrated prominent hypertriglyceridaemia (HTG) of 19.5 mmol/L (severe HTG: 11.2–22.4), detectable urine ketones and a random blood glucose of 13 mmol/L dropping to 10.5 mmol/L on repeat (normal random <11). Ketone levels were deemed consistent with fasting ketosis after 48 h of vomiting. There was no known history of diabetes in the patient. Management included aggressive rehydration and pain control, yet the patient rapidly decompensated into shock requiring intensive care unit support. Blood gases revealed severe metabolic acidosis (pH 6.99) and unsuspected underlying diabetic ketoacidosis was diagnosed. The HTG gradually resolved following intravenous fluids and insulin infusion with slower correction of the metabolic acidosis. Importantly, her glycated haemoglobin was 12%, indicating the silent presence of chronic glucose elevations.