Metformin for Older Patients With Heart Failure With Preserved Ejection Fraction

Inclusion Criteria: * Heart failure with preserved ejection fraction (HFpEF) will be defined in accord with the American College of Cardiology/American Heart Association 2013 guidelines statement on Management of heart failure and as previously described. The 4 key inclusion criteria for HFpEF include: 1) clinical signs and symptoms as scored by National Health and Nutrition Examination Survey (NHANES)-HF Clinical Score ≥3 and the Rich Criteria; 2) a normal left ventricular (LV) ejection fraction (≥50%) by echocardiography; 3) LV diastolic dysfunction \> grade 1 (American Society of Echocardiography Recommendations); 4) no evidence of significant ischemic, valvular, pulmonary or other medical disorder to account for their symptoms. * Age ≥60 * Stable HF symptoms and medications for ≥3 weeks * Final eligibility will be based upon all information available at the conclusion of the baseline visits tests, including review of hospital and outpatient records, history, physical examination, echocardiogram, and familiarization/screening exercise test by a board-certified investigator cardiologist who have extensive experience in heart failure investigations in older persons with HFpEF Exclusion Criteria: * History of treatment with metformin or other anti-diabetic drug intended to treat diabetes * Body mass index (BMI) \<25.0 * Uncontrolled dysrhythmia * Uncontrolled hypertension (systolic blood pressure \[SPB\]\>200 mmHg or diastolic blood pressure \[DBP\]\>100 mmHg at rest) * Si…