Diabetes mellitus is a common chronic metabolic disease that seriously harms human health. Therefore, there is a need to develop recent co-treatment strategies of plant origin which might have no side effects and are cost-effective. Watercress (Nasturtium Officinale) has anti-diabetic, antioxidant, and anti-inflammatory effects as documented previously. This study was conducted on 60 healthy male albino rats to investigate fasting blood glucose, insulin hormone, blood lipid profile (triglycerides, total cholesterol, LDL, and HDL), kidney functions (creatinine and urea), liver functions (ALT and AST) and cumulative blood sugar (HbA1c). The study was designed by dividing the rats into 4 groups: Group 1 (Negative Control Group), Group 2 (Diabetes positive Control injected with (45mg/kg body weight) Streptozotocin intraperitoneally), Group 3 (100 mg watercress /Kg body weight for 8 weeks, daily) and Group 4 (200 mg watercress /Kg body weight for 8 weeks, daily). Blood was collected after scarification on weeks 2, 4, 6, and 8 of the experiment for serum separation, and blood was collected on EDTA tubes for HbA1c at week 8 only. The results of this study indicated that the treated group exhibited a significant and progressive decrease in fasting blood glucose, triglycerides, total cholesterol, LDL, HDL, creatinine, urea, ALT, and AST and a significant and progressive increase in insulin hormone at all experiment times compared to the controls. Shifting to HbA1c, the 3rd and 4th groups showed a significant decrease compared with the controls at 8 weeks of the experiment. We concluded that administration of watercress aqueous extract at 200 mg watercress /kg body weight has hypoglycemic and hypolipidemic activity.