INS and diabetes mellitus: Subsequently, Moore proposed the hypothesis that intestinal secretions might have a glycemic-lowering effect in diabetics, which was the first study to suggest an effect of intestinal secretions on blood glucose (Moore, 1906), and in the 1960s a team of researchers in the UK and the US independently discovered the “incretin effect,” in which oral glucose markedly stimulates insulin secretion, setting the stage for the subsequent development of incretin (Elrick et al., 1964; McIntyre et al., 1964).