CCK and diabetes mellitus: There are major discrepancies between – on one hand – man and pig (abundant islet-cell expression of the CCK2 receptor) and – on the other hand – between rodents and dogs, where the specific CCK1 receptor is more abundant.16,61,62 Consequently, results on the insulinotropic effects of CCK and gastrin obtained from rat, mice, and dog studies do not necessarily apply to human physiology and diabetes pathophysiology.