What if FGF21? What is FAP? why was it chosen as a potential target for anti-diabetic therapy? what results suggest that this might be problematic, i. e., that the response might not be what was hoped?

FGF21 is Fibroblast Growth Factor 21 and FAP is Fibroblast Activation Protein. It has been said that it can lower blood glucose and raise insulin responsiveness, however, only 40% agreed to it and the rest got additional anti-diabetic agent to provide a better control of glucose levels.