Ideally, the blood samples will be taken in a fasted state (i.e. in the morning without having had breakfast), whereas the fitness test will be done after the patient has last had some food. The investigators will therefore provide the participants with a light snack after the blood sample has been taken. In case a patient cannot attend the hospital in the morning in a fasted state then they will arrange the session at a later time of day and the patient will not be required to be fasted (leading to loss of some of the secondary outcome measures which require a fasted state).