Prior diabetes diagnosis, low admission glucose <100 mg/dl, any condition affecting HbA1c e.g. known haemoglobinopathies, recent blood loss, significant anaemia (Hb <10), red blood cell transfusion within 6 months of admission, significant kidney disease or EPO, >65 y/o with very poor health or end‐stage disease on palliative care, pregnancy, admission due to DKA or hyperglycaemic hyperosmolar state, HbA1c measurement within 3 months of admission. Here, GSTM1 is linked to anemia (phenotype).