A Scoping Review of Clinical, Genetic, and Mechanistic Evidence Linking IL-6/IL-6R Signaling and Type 1 Diabetes Mellitus

Type 1 diabetes mellitus (T1DM) is an autoimmune disease characterized by immune-mediated β-cell destruction, where interleukin-6 (IL-6) signaling plays a complex and context-dependent role. Tocilizumab, an IL-6 receptor (IL-6R) inhibitor, is effective in several autoimmune conditions, but its influence on the onset and progression of T1DM remains uncertain. This scoping review aimed to map current clinical, genetic, and mechanistic evidence linking IL-6/IL-6R signaling to T1DM risk and to identify key research gaps. Following PRISMA-ScR guidelines, PubMed, Embase, and Web of Science were searched for studies from 2005 to 2025 reporting associations between tocilizumab or IL-6R modulation and T1DM onset. Six studies were included: one case report describing T1DM onset during tocilizumab therapy in a genetically predisposed patient, one randomized controlled trial showing no significant β-cell preservation with tocilizumab, three Mendelian randomization analyses with conflicting findings on IL-6R signaling, and one mechanistic study showing enhanced IL-6 responsiveness in early-stage T1DM. Collectively, evidence remains fragmented and inconclusive, highlighting research gaps in the differential roles of IL-6 classic versus trans-signaling and the impact of genetic predisposition. Future prospective studies should clarify whether selective IL-6 trans-signaling blockade may offer safer, targeted strategies for modulating autoimmune β-cell destruction.