Background: Androgen deprivation therapy (ADT) for prostate cancer treatment induces a metabolic syndrome, which may contribute to non-cancer-related morbidity and mortality. Metformin may abrogate these effects. Additionally, metformin has potential antineoplastic activity in various malignancies including prostate cancer. Materials and methods: A literature review using PubMed with the keywordsAMPK, androgen deprivation therapy, insulin resistance, metabolic syndrome, metformin and prostate cancer was undertaken. Results: This overview will look at the current evidence linking ADT and metabolic syndrome while discussing ongoing clinical trials under way assessing the effectiveness of metformin in abrogating these effects. The potential antineoplastic activity of metformin, mediated by multiple proposed mechanisms based on evidence from preclinical and clinical studies, will also be elucidated in this review. Conclusions: Overall available data support the potential dual benefit of metformin on ADT-induced metabolic syndrome and in its antineoplastic activity in prostate cancer, justifying the need for ongoing clinical trials to confirm these effects as the evidence currently available for standard practice is lacking.