Alloxan was one of the usual substances used for the induction of diabetes mellitus. It has a destructive effect on the β cells of the pancreas. Glibenclamide was an oral sulphonylurea antidiabetic preparation and widely used as standard drug in antidiabetic study. In the hypoglycaemic study of C. tinctorius L. petals extract in alloxan induced diabetic rats, significant increase in serum fasting blood glucose level with decrease in body weight were observed. On the other hand, petals extract treatment to animals produced a dose related hypoglycaemic effects. The increased blood glucose level was brought down and gain in body weight was seen.
 Alloxan effectively induced diabetes in normal rats that are reflected by elevated levels of blood glucose, glycosylated Hb and reduced levels of body weight, liver, pancreas and kidney glycogen, insulin of the injected animals. Treatment with standard drug glibenclamide and methanolic and aqueous extracts of C. tinctorius L. petals reversed these conditions. While comparing plant extracts for antidiabetic study, aqueous extract of C. tinctorius L. petals showed better activity than the methanolic extract. Decrease in glycogen content of liver, pancreas and kidney were in diabetic control rats were due to the leakage of insulin in diabetic state. Prevention of glycogen depletion in the liver following administration of petals extract and standard drug could have been achieved by stimulation of insulin release. The highest improvement was recorded in 600 mg/kg b.w. dosage of C. tinctorius L. (petals).