Cardiovascular morbidity and mortality are increased in transplant recipients, and diabetes mellitus is among the main determinants of this increase. This review focuses on the influence of diabetes on survival and functional outcomes in transplant recipients, the prevalences of post-transplantation hyperglycaemia and diabetes, the mechanisms of diabetes in transplant recipients, the respective roles of immunosuppressive drugs, the predictive factors, and the practical implications. Although available studies show that calcineurin inhibitors have diabetogenic effects and that these are more marked with tacrolimus, emphasis should be put on the major diabetogenic role of corticosteroids. This warrants efforts to develop immunosuppressive regimens that eliminate or reduce the need for corticosteroids.