Coeliac disease (CD) develops in genetically susceptible individuals who, in response to unclear environmental triggers, develop an immune response triggered by gluten ingestion. It is now recognised as a global disease affecting about 0.7% of the world's population. The clinical presentation ranges from malabsorption to asymptomatic individuals diagnosed by screening high-risk groups. Diagnosis requires the demonstration of small intestinal villous atrophy in the presence of circulating coeliac auto-antibodies and/or an unequivocal response to a gluten-free diet (GFD). Recent guidelines suggest that, in a subset of children, duodenal biopsies can be avoided in the presence of strict symptomatic and serological criteria. While the majority of patients respond to a GFD, up to 20% of patients with CD have persistent or recurrent symptoms. There are several aetiologies for residual or new symptoms in a patient with CD on a GFD, with inadvertent exposure to gluten being the most common. Following a GFD can be challenging for patients with CD and understanding the barriers/challenges faced by patients in maintaining a GFD is crucial for compliance. Abbreviations: AGA: anti-gliadin antibodies; Anti-DGP-ab: anti-deamidated gliadin peptide antibodies; Anti-tTG-ab: anti-tissue transglutaminase antibodies; ATD: auto-immune thyroid disorders; BMD: bone mineral density; CD: coeliac disease; DH: dermatitis herpetiformis; EMA: anti-endomysial antibodies; FDR: first-degree relatives; GFD: gluten-free diet; HbA1c: haemoglobin A1c; HLA: human leucocyte antigen; IBS: irritable bowel syndrome; LMIC: low- and middle-income countries; NPV: negative predictive value; NRCD: non-responsive coeliac disease; POCT: point-of-care tests; SDR: second-degree relatives; SIBO: small intestinal bacterial overgrowth; T1DM: type 1 diabetes mellitus; ULN: upper limit of normal.