GCG and type 2 diabetes mellitus: However, several studies found that GLP-1 did not enhance insulin actions in humans.107 Further, a study found that after T2D patients had bariatric surgery, GLP-1R expression in adipose tissue did not affect metabolic outcomes such as insulin sensitivity improvement, T2D remission and weight loss.287 Therefore, it is a matter of debate currently whether GLP-1 enhances the insulin actions on adipocytes, liver and skeletal muscle.