Diabetes mellitus is a chronic disease in which the infected cells do not have the ability to produce sufficient amount of insulin that results in the abnormality of carbohydrates metabolism and an increase in blood glucose level. Long time exposure to diabetes mellitus results in failure or dysfunction of different organs like kidneys, nerves, heart, eyes, etc. A common practice to cure diabetes is the use of a-glucosidase inhibitors which help in lowering the blood glucose level. We presented 1, 2-benzothiazine 1, 1-dioxide derivatives as novel and more potent a-glucosidase inhibitors via their in vitro and in silico screenings. Excellent enzyme inhibitions were observed for compounds 2, 8, 10 and 12 having IC50 values of 6.91, 14.0, 4.2, 5.9 and 29.2µM respectively which were found better than the reference acarbose (IC50= 38.31µM). Molecular docking studies suggested high binding energies and good binding interactions of these compounds with the active site residues of the receptor protein. A good agreement was found between the results of both modes of evaluation. Moreover, the envisioned candidates have a good potential to treat diabetes.