Metformin Hydrochloride in Preventing Oral Cancer in Patients With an Oral Premalignant Lesion

Inclusion Criteria: * Participants with oral leukoplakia or erythroplakia with mild, moderate, or severe histologic dysplasia, or hyperplasia not associated with mechanical factors such as ill-fitted dentures * Measurable disease - minimum lesion size of 8 x 3 mm before initial biopsy * Karnofsky performance status \>= 70% * Leukocytes \>= 3,000/microliter * Absolute neutrophil count \>= 1,000/microliter * Platelets \>= 100,000/microliter * Total bilirubin =\< 1.5 × institutional upper limit of normal (ULN) * Aspartate aminotransferase (AST) (serum glutamic oxaloacetic transaminase \[SGOT\])/alanine aminotransferase (ALT) (serum glutamate pyruvate transaminase \[SGPT\]) =\<1.5 × institutional ULN * eGFR \> 40 mL/min using the Cockcroft-Gault equation * Life expectancy \> 3 months * Willing to use adequate contraception (barrier method, abstinence, subject has had a vasectomy or partner is using effective birth control or is postmenopausal) for the duration of study participation * Ability to take oral medication * Ability to understand and the willingness to sign a written informed consent document Exclusion Criteria: * Patients with diabetes who are taking insulin or oral agents * History of diabetic ketoacidosis * Participants may not be receiving any other investigational agents within past 3 months * History of allergic reactions attributed to compounds of similar chemical composition to metformin or prior use of metformin within the last year * Uncontrolled intercurre…