1.|The insulinogenic factor of the gastrointestinal mucosa named“incretin” is only one part of the complex enteroinsular axis. — 2. Of the chemically defined gastrointestinal hormones GIP is the strongestincretin candidate. — 3. Because of the dual function of GIP as gastrone and insulinotropic substance several safeguards against GIP-mediated insulin hypoglycaemia exist. — 4. No pathological condition has yet been found which is causally related to hyper- or hyposecretion of GIP. However, an exaggerated GIP response (usually secondary to the disease) may participate in the pathogenesis of hyperinsulinaemia of patients with obesity and duodenal ulcer. — 5. The injection of GIP antibodies only partially abolishes theincretin effect. Therefore, GIP, although important, is not the onlyincretin.