Diabetes mellitus (DM) is one of the most common complications after kidney transplantation and is associated with unfavorable outcomes including death. DM can be present before transplant but post-transplant DM (PTDM) refers to diabetes that is diagnosed after solid organ transplantation. Despite its high prevalence, optimal treatment to prevent complications of PTDM is unknown. Medical therapy of pre-existent DM or PTDM after transplant is challenging because of frequent interactions between antidiabetic and immunosuppressive agents. There is also frequent need for medication dose adjustments due to residual kidney disease and a higher risk of medication side effects in patients treated with immunosuppressive agents. Sodium-glucose cotransporter 2 inhibitors have demonstrated a favorable cardio-renal profile in patients with DM without a transplant and hence hold great promise in this patient population although there is concern about the higher risk of urinary tract infections. The significant gaps in our understanding of the pathophysiology, diagnosis, and management of DM after kidney transplantation need to be urgently addressed.