Immunogenicity, efficacy and safety of a biosimilar insulin glulisine compared with originator in adults with type 1 diabetes mellitus: A phase III randomised clinical trial

Aims To evaluate the immunogenicity, efficacy, and safety of a biosimilar insulin glulisine candidate (T‐Glu) compared to the reference product (R‐Glu) in patients with type 1 diabetes mellitus (T1DM). Materials and Methods In this phase III, randomised, open‐label trial, adult patients with T1DM received either T‐Glu or R‐Glu by prefilled pens as their bolus insulin for 26 weeks. The primary outcome was the proportion of patients with an immune response at Week 26. Secondary endpoints included changes in glycaemia control parameters, insulin dose stability, treatment satisfaction, and other immunogenicity and safety outcomes. Results By Week 26, the immune response persisted in 16% of patients in the T‐Glu group and 24% in the R‐Glu group ( p > 0.05), confirming similar immunogenicity. HbA1c reduction at Week 26 compared to baseline was similar between groups, with a mean change of 0.53% ± 1.19% in the T‐Glu group and 0.38% ± 1.46% in the R‐Glu group (mean difference: −0.15%, 95% CI: −0.50 to 0.20), demonstrating non‐inferiority (according to a predefined margin of 0.4%). Fasting plasma glucose levels and the seven‐point glucose profile showed no significant differences between groups ( p > 0.05). Insulin dose remained stable throughout the study, and treatment satisfaction scores improved comparably in both groups ( p > 0.05). The total number of AEs was similar, and hypoglycaemia was more frequent in the R‐Glu group ( p < 0.001), with no new safety concerns identified. Conclusions T‐Glu demonstrated similar immunogenicity, efficacy, and safety to R‐Glu in adults with T1DM, supporting its use as a biosimilar insulin glulisine. ClinicalTrials.gov : NCT07070752.