The advent of insulin biosimilars has ushered in a new era in the treatment of diabetes mellitus, promising increased accessibility and affordability of this life-saving medication. This comprehensive review explores the evolving landscape of insulin biosimilars, focusing on their therapeutic equivalence, regulatory considerations, and clinical implications. Biosimilars are biological drugs produced using innovative technologies that replicate the structure and action of the reference drug in a very close way and are not inferior in effectiveness and other characteristics to the original, but are more affordable in pricing. Assessing their therapeutic equivalence requires a multifaceted approach including physicochemical and biological characterization, preclinical studies, and performance testing. The introduction of biosimilar drugs into clinical practice is gradually gaining importance for global health, especially in the treatment of oncological, autoimmune, endocrine diseases and, in particular, diabetes. The process of their registration and introduction into patient treatment practice has already been standardized in developed countries, international documents necessary for implementation have been issued, and convincing and clear confirmation of the positive results obtained during preclinical and clinical studies proving the bioequivalence and interchangeability of the biosimilar and the reference drug is required. The clinical implications of insulin biosimilars are of paramount importance, impacting patient outcomes, healthcare costs, and overall diabetes management. This review synthesizes existing evidence on the efficacy, safety, and immunogenicity of insulin biosimilars, providing insights into their potential role in diabetes therapy. Insulin biosimilars represent a promising avenue for expanding access to insulin therapy while addressing the economic burden of diabetes care. This review underscores the importance of continued research, robust regulatory oversight, and informed clinical decision-making to maximize the benefits of insulin biosimilars for patients and healthcare systems worldwide.
