Sodium/glucose cotransporter-2 inhibitors (SGLT2i) are a new type of glucose-lowering drug that can reduce blood glucose by inhibiting its reabsorption in proximal tubules and by promoting urinary glucose excretion. SGLT2i are widely used in the clinical treatment of type 2 diabetes mellitus (T2DM). In recent studies, SGLT2i were found to not only reduce blood glucose but also protect the heart and kidney, which can significantly reduce cardiovascular events, delay the progression of renal failure, greatly improve the quality of life of patients, and reduce medical expenses for families and society. As adverse cardiac and renal events are the most common and serious complications of T2DM, it is very important to understand the cardio- and renoprotective mechanisms of SGLT2i. This article reviews the historical development, pharmacological mechanism, heart and kidney protection and safety of SGLT2i. The information presented provides a theoretical basis for the clinical prevention and treatment of diabetes and its complications and for the development of new glucose-lowering drugs.