1)Coronary event or procedure(myocardial infarction, unstable angina, coronary artery bypass, surgery or coronary angioplasty) in the previous twelve weeks; 2) PSA > 4ng/ml; 3)Hemoglobin A1c > 8%; 4)h/o prostate carcinoma; 5)Hepatic disease (transaminase > 3 times normal) or cirrhosis; 6)Renal impairment (defined as GFR<30); 7)HIV or Hepatitis C positive status; 9)Participation in any other concurrent clinical trial; 10)Any other life-threatening, non-cardiac disease; 11)Use of over the counter health supplements which contain androgens; 12)Use of an investigational agent or therapeutic regimen within 30 days of study; 13)prostate nodule or severe enlargement on digital rectal examination; 14)Use of testosterone currently or in the past 4 months; 15)Hematocrit > 50%; 16)History of untreated severe obstructive sleep apnea(defined as apnea-hypopnea index ≥30); 17)symptoms suggestive of severe BPH; 18)Congestive heart failure, class III or IV; 20)Known to have anemia secondary to iron, B12 or folic acid deficiency; 21)bone marrow disorder such as myelodysplasia or aplastic anemia; 22) currently suffering from symptomatic depression, with or without treatment; 23) history of severe depression in the past which needed hospitalization; 24)currently suffering from foot ulcer, significant periodontal disease or any other chronic infectious condition; 25)planning to have children. 26) Subjects on testosterone or with testosterone replacement in the past 4 months will be excluded.