Study of Metformin Plus Oligomeric Procyanidin Complex for Pharmacologic Manipulation of AGE (Advanced Glycation Endproducts) Levels in Prostate Cancer Patients

Inclusion Criteria: 1. Confirmation of adenocarcinoma of the prostate that is documented by one of the following: pathology report or clinic note with documented history of prostate cancer. 2. Subjects must be receiving ADT with a GnRH agonist or antagonist, with or without an anti-androgen, with a current testosterone level documented to be \<50ng/dL at enrollment. Subjects whose ADT is interrupted may enroll or continue on study as long as the testosterone is documented to remain \<50ng/dL for the entire duration of study participation. Subjects who have undergone orchiectomy are also eligible. 3. Subjects must have adequate hematologic, renal, and hepatic function at baseline, as follows: * Hematology parameters: ANC \>1000/mcL, platelets \> 100,000/mcL, Hgb \>8.0gm/dL * Renal Function: eGFR of ≥ 45mls/min using Cockkroft and Gault formula (see appendix C). * Liver Function: Total bilirubin ≤ULN, AST and ALT \<1.5xULN, Prior radiation therapy allowed 4. Subjects may have diabetes mellitus but must not be taking metformin. 5. Able to swallow and retain oral medication 6. ECOG performance status of 0 - 2 7. Ability to sign written informed consent 8. Testosterone level \<50ng/dL at time of enrollment. 9. Age 18 or older. Exclusion Criteria: 1. Known allergy to grapes or grape seed 2. Known hypersensitivity or intolerance to metformin. 3. Any condition associated with increased risk of metformin-associated lactic acidosis (e.g. congestive heart failure defined as NYHA Class III or IV functional status, history of acidosis of any type; habitual intake of 3 or more alcoholic beverages per day). 4. Prior cytotoxic chemotherapy for metastatic prostate cancer; prior treatment with genomically-targeted agents, or Provenge is allowed. 5. History of receiving more than 2 classes of ADT. 6. Current use of metformin, or strong antioxidants (extracts from grape seed, milk thistle; pine bark, green tea, saw palmetto; resveratrol; flavonoids; catechins; ellagic acid), large quantities of red grapes, white button mushrooms, red wine 7. PSA doubling time of \<6 months, measured over the 3 months prior to enrollment.