GIP and cystic fibrosis: In another study of 25 adults with pancreatic-insufficient cystic fibrosis (PI-CF), i.v. GIP infusion (4 pmol/kg/min for 80 min) acutely reduced plasma CTX levels after 30 min, suggesting that the bone anti-resorptive effect of GIP is retained in PI-CF, even though its insulinotropic action is blunted in this population [103].