Regarding the serum GLP-1 and insulin levels, the levels of GLP-1 in T2DM and T2DM + sham group were significantly lower than NC group, compared with the T2DM + sham group, GLP-1 levels increased dramatically in T2DM + RYGB and T2DM + EX-4 groups (Figure 6H); insulin content was decreased in T2DM and T2DM + sham groups when compared with NC group. This evidence concerns the gene GCG and type 2 diabetes mellitus.