Polycystic ovary syndrome (PCOS) is the most common endocrinopathy in women of reproductive age. PCOS is not only the leading cause of anovulatory infertility but is also associated with an array of metabolic disorders, among which impaired glucose metabolism has been a topic of intense research. The aim of the present narrative review is to summarize the findings of the studies that have evaluated the prevalence and incidence of prediabetes and type 2 diabetes mellitus (T2DM) in patients with PCOS, to analyze the factors underpinning the association between T2DM and PCOS and to discuss the current strategies for screening and management of impaired glucose metabolism in this population. Both prediabetes and T2DM are highly prevalent in patients with PCOS. Accordingly, regular screening is recommended in this population for the early identification of impaired glucose metabolism, particularly in overweight or obese patients and in those with a family history of T2DM. Prevention of T2DM in patients with prediabetes is primarily based on lifestyle changes, while metformin might be considered in selected cases. The treatment of T2DM is similar in patients with and without PCOS but appropriate contraceptive measures should be implemented in patients receiving treatments other than insulin, metformin or glyburide.