Prostate cancer is the most common gender-specific malignancy in men in the USA. Androgen-deprivation therapy (ADT) is commonly used in the treatment of metastatic or recurrent prostate cancer. The use of ADT is increasing with the advocacy of adjuvant and neoadjuvant ADT for treating asymptomatic patients with locally advanced prostate cancer. Although the use of ADT has resulted in improved survival in men with advanced prostate cancer, ADT, with its resulting severe hypogonadism, causes profound metabolic side-effects. We comprehensively reviewed previous reports using Medline searches of English-language literature (1950 to the present), with the keywords ‘hypogonadism’, ‘testosterone’, ‘androgen deprivation therapy’, ‘hormonal treatment’, ‘prostate cancer’, ‘diabetes’, ‘metabolic syndrome’, and ‘cardiovascular disease’. Men with prostate cancer who undergo long-term ADT are at greater risk of developing dyslipidaemia, insulin resistance, hyperglycaemia and metabolic syndrome. These metabolic and physiological changes are a direct result of the induced severe hypogonadism and might predispose patients to a greater risk of cardiovascular morbidity and mortality. There is a need for prospective studies aimed and designed to investigate the metabolic and cardiovascular adverse effects of ADT, and assess the benefit/risk ratio, especially in special populations such as diabetics.