This project is going to ask dialysis patients (both diabetic and non-diabetic) to undergo a series of tests at three different time points over a one year period: a baseline set of tests, tested when haemoglobin is maintained at 130-140g/L and repeat the tests when haemoglobin is maintained at 105-115g/L. The current recommendation for haemoglobin is 110-120g/L. Patients will not be required to take any study medication but a specialist kidney doctor, using their usual medications of iron and erythropoietin therapy, will change their haemoglobin levels.