YM-543, also known as ASP-543, is a selective SGLT2 inhibitor. Sodium-glucose cotransporter 2 (SGLT2) is a specifically expressed transporter in the kidney that plays an important role in renal glucose reabsorption, and its inhibition may present a novel therapeutic strategy for treating diabetes. YM543 potently and selectively inhibited mouse and human SGLT2 activities at nanomolar ranges. In vivo single oral administration of YM543 dose-dependently and significantly reduced blood glucose levels and improved glucose tolerance with a concomitant increase in urinary glucose excretion in KK/Ay type 2 diabetic mice, effects that were sustained even after 12 h.