Metformin for the Treatment of Endometrial Hyperplasia

Inclusion Criteria: * Be between the ages of 18-75 years old * Have a confirmed diagnosis of endometrial hyperplasia without atypia based upon endometrial biopsy * Have no contraindications to short-term metformin therapy * Have a creatinine clearance of ≥ 90 ml/min, as calculated by the Cockroft-Gault formula * Have normal serum transaminase values (AST and ALT) * Need to be able to undergo metformin treatment for a duration of 12 weeks prior to repeat endometrial biopsy Exclusion Criteria: * Are currently taking metformin or have taken metformin in the past 6 months or have a history of an allergic reaction or intolerance at any time to metformin * Have a history of liver or renal dysfunction. * Have a random glucose of ≤ 65 or ≥ 200 * Have a recent history of alcoholism. Former alcoholics who have abstained from alcohol for 5 years or more may be enrolled in this study. * Have a history of vitamin B12 deficiency * Are pregnant * Are currently taking insulin * Are taking a drug that may significantly interact or influence the metabolism of metformin * In the opinion of the investigator, the patient is felt not to be appropriate for the study