Screening for TODAY Screening is done in a series of steps to help staff evaluate potential participants, assess whether they can safely tolerate metformin, and see how well they perform the study tasks of taking medication and keeping records. During an initial screening phase, potential participants: are given information about the study have their medical history and records reviewed receive blood, urine and other tests If they are still found to be eligible, potential participants complete a run-in phase, where TODAY staff: work to get participants on the maximum tolerated dose of metformin (500-1000 mg bid) wean them from all other diabetes medications provide a comprehensive program of standard diabetes education assess participants ability to keep records, monitor blood sugars, attend screening visits and do other TODAY tasks. If participants successfully complete the screening process, they will be randomized into one of the three treatment arms. Those who are ineligible will be referred back to their physicians/clinics.