An article published in the January 4th, 2014 issue of the journal European Urology reported the outcome of a Swiss trial involving men with hormone-resistant (refractory) prostate cancer (defined as a testosterone level of less than 50 ng/dL with progressive disease) who were given the anti-diabetic drug metformin. For the trial, 44 non-diabetic men who had not been treated with chemotherapy for progressive, metastatic hormone-resistant prostate cancer causing few or no symptoms were given 1,000 mg (one gram) of metformin twice a day until disease progression. Assessment of disease status- included computer tomography of the abdomen, pelvis and chest, bone scanning and serum prostate cancer-specific antigen (PSA) level measurement- was conducted every 12 weeks. After initiation of metformin therapy, 36% of the group was progression-free at 12 weeks and 9% were still progression-free at 24 weeks. PSA doubling time, a measure of disease progression, was beneficially prolonged in 52% of patients after the initiation of metformin. It should be noted that metformin is also associated with improved insulin sensitivity. It should be administered only under a physician’s approval, care and control.