Inclusion Criteria:  • HbA1c > 48 mmol/mol  Exclusion Criteria:  they present with severe renal impairment (eGFR < 30ml/min) they use concomitantly GLP-1 Receptor agonists (which reduce glucagon and therefore hydroxybutyrate production); they currently participating in a very low calorie diet or restricted carbohydrate diet (which artificially increase endogenous ketone production); they present uncontrolled hypertension (systolic blood pressure > 180 mmHg); they have a history of myocardial infarction or cerebro-vascular events in the last 3 months; have a a BMI > 40 kg/m2; they are unable to exercise; they have an allergy or intolerance to ketone esters ; they are unable to give informed consent have any other serious medical condition which in the opinion of study investigators would interfere with safety or data interpretation.