Interventions Against Insulin Resistance in Pulmonary Arterial Hypertension

The investigators propose to test the hypothesis that interventions to improve insulin resistance will improve exercise capacity and World Health Organization (WHO) functional class in PAH. The investigators propose three specific aims to test this 1) A prospective 2x2 factorial design 12-week clinical trial of metformin or placebo and activity intervention or usual care to assess effect on six minute walk and WHO functional class, 2) Assessment of the interventions in Aim 1 in a subset of patients on right ventricle (RV) and peripheral muscle function and lipid content and markers of pulmonary vascular disease to define how these interventions may work in PAH and 3) Identify and prospectively test peripheral blood markers of metformin response in PAH. The broad goals of this work are to demonstrate the efficacy and mechanisms of interventions against insulin resistance in PAH and to identify which patients are most likely to benefit from these interventions, moving to precision medicine in PAH. The investigators are planning a factorial design trial. Patients will be randomized twice. The first is metformin or placebo and is quadruple randomized. The second is mobile health (mHealth) intervention via texts or standard of care and is not blinded to the patients, but is to the investigator and thus is triple randomized.