The field of nanotechnology is the most effective and active area of research in modern materials science. Though there are many chemicals as well as physical methods, green synthesis of nanomaterials is the most emerging method of synthesis. We report the green synthesis of titanium dioxide nanoparticle using leaves of medicinal herb Pterocarpus dalbergioides. Pterocarpus dalbergioides, often known as Andaman Padauk, is an indigenous tree to India's Andaman Islands. We extracted the leaves of Pterocarpus dalbergioides using aqueous solution. We have characterized using UV, FTIR, XRD and SEM/EDAX analysis. The anti-diabetic activity by alpha amylase assay and alpha glucosidase assay was performed. The leaves of Pterocarpus dalbergioides were found to have anti-diabetic activity.