Diabetes mellitus is a group of metabolic disorders characterized by hyperglycemia resulting from defects in insulin secretion, insulin action or both. Though there are various synthetic drugs available for the treatment of Diabetes Mellitus, they are associated with one or more side effects. Hence herbal drugs are gaining popularity to treat diabetes. The present study was aimed to evaluate the antihyperglycemic effects of Narengi crenulata leaf extracts i.e Narengi crenulata methanol extract (NCME) and aqueous extract (NCAE) in streptozotocin (STZ) induced diabetic rats. Animals were divided into 6 groups (n=6). Group I (normal control), Group II( diabetic control), Group III (diabetic +NCME 500mg/Kg bw), Group IV (diabetic + NCAE 500mg/kg BW), Group V (Diabetic NCME+ 750mg/kg bw), and Group VI (diabetic NCAE+ 750mg/kg.bw). Among these extracts, the aqueous extract NCAE (Group VI) at a dose of 750 mg/kgbw. has produced significant antihyperglycemic effect when compared to the 500mg/kg bwt. dose of NCAE and the two doses of NCME. Blood glucose levels were measured after administration of the extracts at every one hour interval upto six hours in all the groups of rats.