By using SNAC formulation to improve bioavailability of GLP-1, oral Semaglutide (Rybelsus®) is available now for T2D patients, although at the expense of a higher dose, yet compromised efficacies of glucose control and body weight loss comparing with injectable Semaglutide, Ozempic® (Rosenstock et al., 2019). Here, GCG is linked to type 2 diabetes mellitus.