Lead Sponsor: Columbia University

Collaborators: National Institute on Aging (NIA), University of Rochester, Emory University, University of Cincinnati, Stanford University, University of Miami, University of Iowa, University of California, Irvine, Medical College of Wisconsin, Boston University, University of Washington, Georgetown University, Johns Hopkins University, University of New Mexico, The University of Texas Health Science Center at San Antonio, Wake Forest University, NYU Langone Health, University of Texas Southwestern Medical Center, University of Kansas Medical Center, University of California, Berkeley, Cornell University, University at Buffalo, Rush University, State University of New York - Upstate Medical University, Eastern Virginia Medical School, Pennington Biomedical Research Center

Intervention / Treatment: DRUG: Placebo oral tablet, DRUG: extended release metformin