Antidiabetic tricyclic compounds

Novel compounds of the structural formula (I), and the pharmaceutically acceptable salts thereof, are agonists of G-protein coupled receptor 40 (GPR40) and may be useful in the treatment, prevention and suppression of diseases mediated by the G-protein-coupled receptor 40. The compounds of the present invention may be useful in the treatment of Type 2 diabetes mellitus, and of conditions that are often associated with this disease, including obesity and lipid disorders, such as mixed or diabetic dyslipidemia, hyperlipidemia, hypercholesterolemia, and hypertriglyceridemia. 新颖的结构式(I)的化合物及其药学上可接受的盐是G-蛋白偶联受体40 (GPR40)的激动剂，并可以用于治疗、预防和抑制由G-蛋白偶联受体40介导的疾病。本发明的化合物可用于治疗II型糖尿病和经常与该疾病有关的病症，包括肥胖和脂质障碍，诸如混合的或糖尿病性的血脂异常、高脂血症、高胆固醇血症和高甘油三酯血症。