Astellas Pharma Inc. said its Suglat tablets have been approved in Japan for treating type 1 diabetes mellitus.

The drug was granted Japanese marketing approval for treating type 2 diabetes mellitus in January 2014.

People with diabetes have abnormally high blood sugar levels. In type 1 diabetes, the patient's body does not produce insulin — a hormone needed to keep blood sugar levels in check — while in type 2 diabetes, patients do not respond to insulin as well as they should.

Suglat was discovered through a collaboration between Tokyo's Astellas and Hanishina, Japan-based Kotobuki Pharmaceutical Co. Ltd.