Euglycaemic diabetic ketoacidosis is a serious but rare adverse effect of treatment with sodium-glucose cotransporter-2 (SGLT-2) inhibitors. A man in his 60s with type 2 diabetes mellitus underwent total hip replacement for an intracapsular neck of femur fracture. His SGLT-2 inhibitor was continued perioperatively and blood glucose levels were normal throughout the admission. A diagnosis of severe euglycaemic diabetic ketoacidosis was made in the operating theatre which required treatment in a critical care unit. This resulted in increased morbidity due to decreased postoperative mobilisation and a new requirement for subcutaneous insulin. This case highlights the need for withholding SGLT-2 inhibitors in patients admitted for emergency surgery and a need for regular ketone monitoring in these patients, even in the context of normoglycaemia.