Due to therapeutic efficacy, Costus igneus Nak. (CI), (popularly known as insulin plant) is one medicinal plant in the limelight of having cure for diabetes. An oral diabetic agent Glimepiride was selected to evaluate the activity in per se and in combination with Costus igneus. The study drugs (glimepiride or Costus igneus leaf juice) were administered orally and blood glucose levels were determined using Glucometer at stipulated time intervals. It perhaps works in pathophysiologic/metabolic deranged conditions as observed by its per se effect in streptozotocin-induced diabetic rats’ contrast to its effect in normal rats. The results of our study confirm that, the combined action of glimepiride and Costus igneus leaf juice has greater antidiabetic effects than their individual effects (per se).