Diabetes Mellitus is a metabolic disorder characterized by hypoglycemia, resulting from absolute or relative deficiency of insulin. Worldwide about 220million people affected. Low-cost herbal treatment is recommended due to their lesser side effect. The aim of the current study was to determine the antidiabetic activity of aqueous leaf extracts of Lagerstroemia speciosa (Lythraceae) and Aegle marmelos (Rutaceae) using alpha amylase inhibition assay and glucose diffusion inhibition assay. In alpha amylase inhibition assay, the leaf extracts of A.marmelos (at a concentration 100µg/ml) exhibited 54.68% of α amylase inhibitory activity with an IC 50 values 92.04µg/ml whereas the leaf extracts of L. speciosa (at a concentration of 100µg/ml) exhibited 60.36% of α amylase inhibitory activity with an IC50 value of 68.19µg/ml .However the mixture of plant extracts (at a concentration of 100µg/ml) exhibited 94.87% inhibition with an IC50 value of 13.145µg/ml. Both plant extracts showed appreciable α amylase inhibitory effects, but the mixture showed more inhibitory effects than the individual plant extracts. In glucose diffusion inhibition assay, the aqueous extract of A. marmelos leaves exhibited maximum glucose diffusion inhibition (76.886%) at 150 minutes as well as L. Speciosa leaf extract showed the maximum inhibition of 79.5357% at the same time interval. The mixture of plant extracts exhibited 87.4274% inhibition at 150 minutes which produces more effects than the two plants.