Diagnosing celiac disease (CD) in individuals adhering to a gluten-free diet (GFD) presents significant challenges. Current guidelines recommend a gluten challenge (GC) lasting at least 6-8 weeks, which has several limitations. Our aim was to compare four approaches previously proposed for diagnosing CD on a GFD: IL-2 serum levels, gut-homing CD8+ T cells, % TCRγδ+ intraepithelial lymphocytes (IELs), and UBE2L3 gene expression. Additionally, we evaluated the CD8+ T-cell-based method with a 3-day GC against the standard GC protocol.