GCG and diabetes mellitus: Furthermore, when STZ‐induced diabetes does alter the position of the glucagon‐AC/cAMP dose response curve in hepatocyte preparations—up or down—it displaces it vertically (i.e., it alters glucagon’s effectiveness) and not horizontally (i.e., it does not alter its potency) (Figure 7) (but see Walsh & Dunbar, 1984).