Diabetes mellitus (DM), one of the most metabolic illnesses, has a major influence on health and quality of life. Phytotherapy has gained a significance as one of the complementary alternative and safe treatment modalities against diabetes than the synthetic medication. Momordica charantia (MC) and Murraya koenegii (MK) are extensively used as antidiabetic agent. In this study, we have examined the effect of oral administration of extracts of MC-fruits and MK leaves in comparison with standard antidiabetic drug, Metformin (120mg/kg body weight) in alloxan induced diabetic albino rat on biochemical parameters such as fasting blood glucose (FBG), hemoglobin, serum creatinine, albumin and urea, serum glutamate oxaloacetate and pyruvate transaminase (SGOT and SGPT), catalase, superoxide dismutase (SOD), and lipid peroxidase (LPO). The results show a significant decrease (p=0.05) in serum glucose levels (range 5.39±0.11 mmol/L to 6.41±0.09 mmol/L) in MC and MK treated diabetic rats and non-diabetic rats fed with both MC and MK (400mg/kg body weight), metformin (4.41±0.07 mmol/L) compared to the alloxan induced non treated diabetic rats (8.41±0.08 mmol/L). The administration of diabetic rats with plant extracts for 14 days periods brought a remarkable alteration in returned blood glucose levels that are close to normal values reported in control group (4.44±0.14 mmol/L. For all the parameters evaluated, the results observed were significant and in close comparison with the standard antidiabetic drug, Metformin. This indicates that the extracts of MC and MK have diminishing effect on severity of diabetes. [ABSTRACT FROM AUTHOR]