The complex metabolic syndrome, diabetes mellitus, is a major human health concern in the world and is estimated to affect 300 million people by the year 2025. Several drugs such as sulfonylureas and biguanides are presently available to reduce hyperglycemia in diabetes mellitus. These drugs have side effects and thus searching for a new class of compounds is essential to overcome this problems. A series of seven novel N-(4-phenylthiazol-2-yl)benzenesulfonamides derivatives were synthesized and assayed in-vivo to investigate their antidiabetic activities by streptozotocin-induced model in rat. These derivatives showed considerable biological efficacy when compared to glibenclamide, a potent and well-known antidiabetic agent, as a reference drug. Four of the compounds were effective, amongst which 13 show more prominent activity at 100 mg/Kg p.o. The experimental results are statistically significant at p < 0.05 level.