Diabetes mellitus is a group of metabolic disorders with great challenge in its treatment due to its pathological complication. In recent decade, there is extensive use of applying nanotechnology to medicinal plants as a trend in diabetes treatment due to phytochemical constituents. The present study aimed to evaluate the hypoglycemic effect of selenium cleome droserifolia nanoparticles (Se-CNPs) and/or Galvus met® treatment on streptozotocin induced diabetes mellitus in male rats. Fifty male Wistar rats were divided equally into five groups: control group, control diabetic group, diabetic group treated with Se-CNPs, diabetic group treated with Galvus met® and diabetic group treated with Se-CNPs plus Galvus met®. Glucose and insulin levels, Alanine Aminotransferase (ALT) and Aspartate Aminotransferase (AST), Total Cholesterol (TC), Triacylglycerols (TG), High Density Lipoprotein (HDL-c), Very Low Density Lipoprotein cholesterol (VLDL-c), Low Density Lipoprotein cholesterol (LDL-c) and (NEFAs), urea and creatinine were evaluated. Also, histopathological changes in pancreatic tissue were examined. The results showed significant elevation in serum glucose concentration, ALT and AST activities, TG, LDL-c, VLDL-c and Non Esterified Fatty Acids (NEFAs), urea and creatinine levels while a significant decrease in serum insulin and HDL-c concentration in untreated diabetic rats when compared with control. Meanwhile, daily administration of Se-CNPs and/or Galvus met® to diabetic rats showed significant amelioration of these parameters.