Objectives: In this study, we investigated the anti-diabetic and anti-inflammatory effects of water extract from leaves of Ligustrum japonicum (WLJ) in db/db mouse. Methods: The db/db mice were treated orally with WLJ (300 mg/kg/day) for 10 weeks to examine the long-term effects on hyperglycemia and glomerular tissue as well as biochemical and functional abnormalities in the kidney. Results: WLJ treatment markedly reduced plasma levels of glucose, triglyceride, creatinine, and systolic blood pressure in diabetic db/db mouse. Treatment of WLJ significantly increased plasma level of high density lipoprotein (HDL)-cholesterol. We also found that overexpressions of vascular cellular adhesion molecule (VCAM)-1 and endothelin (ET)-1 were observed in aortic tissue of db/db mouse, whereas, WLJ suppressed both expression of VCAM-1 and ET-1 in aorta. In renal tissue, overexpressions of ICAM-1 and TGF-b1 were found in untreated db/db mouse, however, significantly decreased those levels by WLJ treatment. The insulin immunoreactivity of the pancreatic islets remarkably increased in WLJ treated db/db mouse compared with untreated db/db mouse. Taken together, WLJ treatment ameliorated hyperglycemia and hyperlipidemia via improvement of insulin secretion and lipid metabolism, respectively, Furthermore, WLJ treatment also ameliorated hypertension via inhibition of inflammatory process in vascular and renal tissues, Conclusions: Ligustrum japonicum has an anti-diabetic and anti-inflammatory effects in db/db mouse, Thus, these results suggested a beneficial effect of Ligustrum japonicum in treatment with diabetes and diabetic vasculopathy.