Efficacy and Safety of Biosimilar Insulin Aspart (Rapilin®) Versus Originator (NovoRapid®) in Type 1 Diabetes: A Multicenter, Retrospective Cohort Study

Data on the biosimilar insulin aspart Rapilin® (“Biosimilar”) in patients with T1DM, particularly in children and adolescents, remain scarce. This study compared the real-world efficacy and safety of Biosimilar and the originator insulin aspart NovoRapid® (“Originator”) in patients with type 1 diabetes mellitus (T1DM). Electronic medical records from 34 hospitals in China covering the period from January 1, 2023 to January 31, 2026 served as the data source for this multicenter, retrospective cohort study. A total of 229 patients with T1DM who had been receiving continuous Biosimilar ( n = 116) or Originator ( n = 113) treatment for ≥ 12 weeks were included. The primary endpoint was the change in glycated hemoglobin (HbA1c) from baseline to the last measurement before January 31, 2026. Treatment-emergent adverse events (TEAEs) were collected and classified. Of the 229 included patients, 112 (48.9%) were men. The Biosimilar and the Originator groups had a mean age of 24.88 ± 17.73 years and 30.69 ± 20.84 years, respectively. The Biosimilar and the Originator groups had significant and comparable HbA1c reduction from baseline (adjusted least squares means − 1.90% vs − 1.59%; difference − 0.32%, 95% confidence interval [− 0.94%, 0.31%], P = 0.322). Furthermore, the Biosimilar group showed a marginally significant trend toward a higher HbA1c target (< 7.0%) achievement rate than the Originator group ( P = 0.056). Changes in fasting blood glucose, total daily insulin dose, and daily prandial insulin dose were comparable between groups. The incidences of TEAEs (37.1% vs 38.9%), including level 1 to 3 hypoglycemia and diabetic ketoacidosis, were comparable between the Biosimilar and Originator groups. However, patients receiving Biosimilar had significantly lower incidence of injection-site reactions than patients receiving Originator (0.0% vs 5.3%, P = 0.014). Biosimilar showed comparable glycemic control, dose stability, and systemic safety to Originator in a diverse T1DM cohort containing a substantial proportion (50.0%) of pediatric and adolescent patients.