Background: Bougainvillea spectabilis and Bougainvillea alba are used for the treatment of diarrhoea, stomach acidity and fertility control. Objective: The aim of this research was to examine the anti diabetic activity of Bougainvillea spectabilis and Bougainvillea alba flowers. Methods: To study the in vitro anti- diabetic effect α-amylase inhibition, glucose diffusion and non-enzymatic glycosylation of hemoglobin assay was performed. Result: The Bougainvillea spectabilis extract showed good glucose tolerance and exhibit anti diabetic effects than Bougainvillea alba and it is validated by traditional claim of this plant.