Metformin for Older Patients With Heart Failure With Preserved Ejection Fraction

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)
• •Significant anemia (\<9.5 g hemoglobin \[Hb\]) (eligibility will be determined by complete blood count)
• •Significant renal insufficiency (estimated glomerular filtration rate \[eGFR\] \<45 ml/min/1.73 m2) (eligibility will be determined by comprehensive metabolic panel)
• •Acute or chronic metabolic acidosis
• •Type 2 diabetes, or HbA1c\>6.5
• •Low vitamin B12 (\<232 pg/mL)
• •Known valvular heart disease, infiltrative cardiomyopathy, or hypertrophic obstructive cardiomyopathy with active obstruction as the primary etiology of HF
• •Evidence of significant chronic obstructive pulmonary disease (COPD) defined as either: a. On continuous home oxygen therapy for COPD; b. Hospitalization for COPD in last 6 months
• •Any condition that in the judgement of the investigator precludes participation in study or study procedures such as significant dementia, mobility impairment, uncontrolled psychiatric disease, etc.
• •Alcohol abuse (\>14 drinks/week)
• •Current or recent cancer, or chemotherapy/radiation treatment
• •Pregnancy-women of child-bearing potential are excluded from participation in this study.
• •A treadmill exercise test revealing: a. Evidence of significant ischemia; b. Electrocardiogram: 1mm flat ST depression; c. Stopped exercising due to chest or leg claudication or any reason other than exhaustion/fatigue/dyspnea; d. Exercise SBP \> 240 mmHg, DBP \> 110 mmHg ; e. Unstable hemodynamics or rhythm; f. Unwilling or unable to complete adequate exercise test
• •Exclusions for microbiome testing: a. Antibiotics use within last 30 days; b. Diarrhea and/or vomiting within last 30 days; c. Surgery related to gut in last 6 months; d. Inflammatory bowel disease (such as Crohn's disease or ulcerative colitis), or irritable bowel syndrome
• •Plans to leave area within 1 year
• •Currently participating in other investigational study
• •Refuses informed consent