In this 12-month clinical trial, a 3-month run-in period will precede the interventional phase of the study. All patients will be placed on treat-to-target insulin regimen alone during the run-in phase. At the end of the 3-month run-in period, all participants will continue on treat-to-target insulin regimen, and will then be randomized to either of the 2 arms of the study: an experimental arm, consisting of treat-to-target insulin regimen plus metformin, and a control arm consisting of treat-to-target insulin regimen plus placebo. Both the physicians and patients will be blinded to the oral agents being administered to patients.