We performed a prospective, non-randomized, multicentre study including 188 CD patients on a GFD and 73 healthy controls on a gluten-containing diet. Subjects were given a dietary questionnaire and fecal GIP quantified by ELISA (iVYLISA GIP-S kit). Serological anti-tissue transglutaminase (anti-tTG) IgA and anti-deamidated gliadin peptide (anti-DGP) IgA antibodies were measured simultaneously.