We can't say a single or multiple targets to discover new anti-diabetic compounds. There are several pathways involved in the regulation of diabetes. Each target has specific role in every biological process. Therefore, first focus on selective pathway which has a vital role in the pathogenesis of diabetes (Ex:OMIM, STRING or REACTOME). Then decide which protein target will be the right one to control the cause of diabetes.
i am not well known to this thechnique but molecules what you are working for i.e. GPR40 is free fatty acid receptor by activation of this receptor your only targeting the reduction of free fatty acid which ultimatly reduces the free fatty acid in body and its synergic effect shows the reductance of insulin resistance. While SLT2 molecule inbition enhances the urinary glucose excretion to achive the normoglycemia. Yes, these molecules may be target but in my point of view you should target other molecules like IRTK ( insulin receptor tyrosine kinase) because in type 2 diabetes insulin is produced in enough amount but due to deformation of IR receptor (present on cell surface) insulin shows resistance. Other molecules should also be targeted i.e Glucosidase, amylase etc in order to achive normoglycemia.