The Sarcopenia Study

Inclusion Criteria: Heart Failure (HF) Patients: Stage A/B HFpEF 1. Established clinical diagnosis of HFpEF (EF\>50%) 2. Clinically stable for ≥ 3 months (no admissions to hospital) 3. Age ≥65 4. Willing to provide written consent for participation in the study. HF Patients: Stage C/D HFpEF and HFrEF 1. Established clinical diagnosis of HFpEF (EF\>50%) OR HFrEF (EF\<40%) 2. Clinically stable for ≥ 3 months (no admissions to hospital) 3. Age ≥65 4. Willing to provide written consent for participation in the study. Healthy volunteers 1\. Age \>18 2. Able to provide written informed consent Asymptomatic T2D 1. Male or female, aged ≥18 and ≤75 years. 2. Diagnosis of stable T2D (determined by i) formal diagnosis in primary care physician case records, ii) a record of diagnostic oral glucose tolerance test OR glycated haemoglobin level ≥6.5%). Exclusion criteria: Heart failure 1. Absolute contraindication to MRI 2. Inability to walk/undertake the 6-Minute Walk Test (6MWT) 3. Neuromuscular disorders that may impact skeletal muscle assessment, such as motor neurone disease, multiple sclerosis, skeletal muscle myopathies and myositis 4. Regular or intermittent oral corticosteroid use 5. Untreated hyper or hypothyroidism 6. Heart failure-related hospitalisations in the last 3 months Healthy volunteers 1. Previous or current signs of HF 2. Risk factors for the development of HF, such as hypertension, diabetes Mellitus or coronary artery disease Asymptomatic Type 2 Diabetes Mellitus (T2D) 1. Angina pectoris or limiting dyspnoea (\>NYHA II) 2. Major atherosclerotic disease: Symptomatic CAD, history of MI, previous revascularisation, stroke/transient ischaemic attack or symptomatic peripheral vascular disease. 3. Atrial fibrillation or flutter. 4. Moderate to severe valvular heart disease. 5. History of heart failure or cardiomyopathy. 6. Type 1 diabetes mellitus (T1DM). 7. Low fasting C-peptide levels suggestive of adult-onset T1DM. 8. Stage III-V renal disease (estimated glomerular filtration rate ≤30ml/min/1.73m2). 9. Absolute contraindications to MRI.