represents the effect of d-limonene on plasma glucose levels at different time intervals in experimental diabetic rats. There was a significant elevation in the level of glucose 96 h after the administration of STZ. The glucose level in diabetes was gradually increased in diabetic rats in 45 days after the administration of STZ. Administration of d-limonene for 45 days gradually decreased the blood glucose level and the maximum effect was observed at a dose of 100 mg/kg body weight.