Objectives: This study is aim to investigate the anti-diabetic effects of Glycine soja Siebold et Zucc. (GS) in diabetic mellitus animal model. Methods: Male BKS.Cg-m＋/＋ Leprdb/J mice (db/db mice) randomly assigned to 3 groups and treated with saline, metformin (150 mg/kg/day, positive control), and GS extract (2 g/kg/day). Body weight, food intake, and fasting blood glucose were monitored every week. After a conse-cutive 6-week treatment, the levels of lipid metabolites and insulin in plasma were measured with biochemistry analyzer. Results: As well as fasting blood glucose and food intake, the levels of triglyceride, total cholesterol, and low-density lipoprotein in plasma were also dramatically decreased in GS group. Also, GS extract administration decreased the total fat mass. However, GS extract could not change the level of high-density lipoprotein and insulin. Furthermore, there was no difference in body weight between control and GS extract-treated group. Conclusions: GS may have a potential to ameliorate diabetes mellitus by improving fasting blood glucose level and lipid metabolites. Further studies are warranted to investigate the underlying molecular mechanism of GS.