New-onset diabetes mellitus after transplantation (NODAT) is common in kidney recipients, threatening health and longevity by predisposing to microvascular and cardiovascular disease and by reducing graft survival. Several risk factors, already present before or arising after transplantation, in particular the employed immunosuppressive regimens, have been related to the development of NODAT. The real incidence of NODAT after kidney transplantation is difficult to establish, because different classification systems and definitions have been employed over the years. Awareness of NODAT and of the NODATrelated factors is of paramount importance for the clinicians in order to individuate higher risk patients and arrange screening strategies. The risk of NODAT can be reduced by planning preventive measures and by tailoring immunosuppressive regimens according to the patient characteristics. Once NODAT has been diagnosed, the administration of specific antihyperglycemic therapy is mandatory to reach a tight glycemic control, which contributes to significantly reduce posttransplant mortality and morbidity. In this review, we summarize current knowledge on risk factors, diagnosis, treatment of NODAT.