Metformin for the Prevention of Oral Cancer in Patients With Oral Premalignant Lesions

Inclusion Criteria: * Age 18-85 * Clinical appearance of lesion * Homogenous leukoplakia * Non- homogenous leukoplakia * Erythroplakia * Proliferative verrucous leukoplakia * Histologic appearance * No dysplasia * Mild dysplasia * Moderate dysplasia * Severe dysplasia * Diabetics: if on metformin, will get them to 2000 mg per day, if not, will add metformin in consultation with endocrinologist * All subjects must be able to comprehend and sign a written informed consent document * Willing and able to be available for the duration of the study * In general good health with no contraindication to biopsy or metformin therapy * Laboratory results Exclusion Criteria: * Carcinoma in-situ, verrucous carcinoma, invasive squamous cell carcinoma (SCCa) * Exclude systemic causes of the lesion: pemphigus, pemphigoid, systemic lupus erythematosus (SLE), lichenoid drug reaction, human immunodeficiency virus (HIV), syphilis * Exclude local inciting factors: rule out (r/o) but allowing 2 weeks to pass and see if there is resolution, if not and doesn't resolve with local measures, medical treatment, enroll * Frictional: sharp tooth * Trauma * Immunosuppression by natural illness or medically induced * Hypersensitivity or allergic reaction to metformin or some other contraindication