Prostate cancer is the most frequently diagnosed malignancy among UK men and accounts for 12% of male deaths. Androgen deprivation therapy (ADT) is commonly used as part of the treatment for prostate cancer. It is effective at suppressing prostate-specific antigen, stabilizing disease, alleviating symptoms in advanced disease, and potentially prolonging survival. However ADT, presumably at least in part owing to low testosterone levels is associated with insulin resistance, the development of metabolic syndrome plus increased overall and cardiovascular disease mortality. We have reviewed the relationship between prostate cancer, ADT, metabolic syndrome, type 2 diabetes, and cardiovascular disease. We have not reviewed other potential medical problems such as osteoporosis. We suggest that there should be a baseline assessment of patients' risk for cardiovascular disease before starting ADT. Consideration should be given to starting appropriate therapies including lifestyle advice, antihypertensive and lipid-lowering agents, insulin sensitizer, plus possibly aspirin. Having started ADT, the patients should have a regular (possibly annual) assessment of their cardiovascular risk factors.