GCG and type 2 diabetes mellitus: For example, the genetically engineered strain Lactobacillus plantarum (L. plantarum)-pMG36e-GLP-1 regulated the intestinal microbiota, the apoptosis of pancreatic islet cells was inhibited, islet β-cell proliferation and insulin secretion were all promoted, and it showed its ameliorative effect on T2DM in artificially induced mice and transgenic mice [50].