Metformin Prostate Cancer Adjuvant Trial

Inclusion Criteria:

Male > 18 years of age
Biopsy confirmed adenocarcinoma of the prostate
Able to swallow and retain oral medication
Hemoglobin A1C <7.0%
Able and willing to participate in the full 12 months of the study
Able to understand instructions related to study procedures
Able to read and write English

Exclusion Criteria:

Metastatic Prostate Cancer
Prostate Specific Antigen Doubling Time < 6 months
Prior Chemotherapy, hormonal therapy, oral glucocorticoid therapy, Gonadotropin-releasing hormone analogue therapy
Current or previous use of 5α-reductase inhibitors, antiandrogen drugs, metformin, oral or injectable diabetes drug
Diagnosis of Type 1 Diabetes Mellitus
Known hypersensitivity to metformin
any condition associated with increased risk of metformin associated lactic acidosis
participation in any investigational or marketed drug trial within 30 days prior to screening or during study period
any unstable, serious co-existing medical conditions including but not limited to myocardial infarction, coronary bypass surgery, unstable angina, cardiac arrhythmias, clinically evident congestive heart failure, or cerebrovascular accident within 6 months prior to screening
history of megaloblastic anemia
abnormal liver function test (total bilirubin, aspartate aminotransferase, alanine aminotransferase, alkaline phosphatase or serum creatinine above upper limit of normal)
history of other malignancies, with the exception of adequately treated non-melanoma skin cancer, stage 1 melanoma, non-muscle invasive bladder cancer, or other solid tumors curatively treated with no evidence of disease for at least 5 years
history or current evidence of substance abuse within 12 months of screening
history of any illness (including psychiatric) that, in the opinion of the investigator, might confound the results of the study or post an additional risk to the subject