Question category: Endocrinology
A 64 year old male presents unwell. He has been suffering from vomiting and diarrhoea for the last few days and has been unable to eat and drink. He is normally well although does suffer from type 2 diabetes mellitus which is normally well controlled. He is currently only on metformin. On examination he is tachycardic and tachypnoeic. There is nil else of note. Bloods reveal an elevated urea (11.0 mmol/L) and creatinine (190 mmol/l) and a bicarbonate of 16mmol/l. An arterial blood gas reveals hydrogen ions of 55. The anion gap is elevated. Urinalysis reveals protein+ but nil else. What is the most likely cause?