This study employed a new‐user cohort design to determine whether, in Japanese adults with type 2 diabetes without prior major cardiac or renal disease, initiating treatment with a biguanide versus an SGLT2 inhibitor—while refraining from using the alternative class during the first year yet allowing any other concomitant medications—produces long‐term differences in the hazards of major cardio‐cerebrovascular events, diabetic complications, or total pharmacotherapy costs. The gene discussed is SLC5A2; the disease is kidney disorder.