Metformin Hydrochloride in Preventing Oral Cancer in Patients With an Oral Premalignant LesionThis phase IIa trial studies how well metformin hydrochloride works in preventing oral cancer in patients with an oral premalignant lesion (oral leukoplakia or erythroplakia).Closed for Recruitment Principal Investigator Miriam RosinBody Locations and Systems Oral CancerArea VancouverAge 18 and above