Background: A wave of expiring patents for first-generation insulin analogues has created opportunities in the global insulin market for highly similar versions of these products, biosimilar insulins. Biologics are generally large, complex molecules produced through biotechnology in a living system, such as a microorganism, plant cell, or animal cell. Since manufacturing processes of biologics vary, biosimilars cannot be exact copies of their reference product but must exhibit a high degree of functional and structural similarity. Biosimilarity is proven by analytical approaches in comparative assessments, preclinical cell-based and animal studies, as well as clinical studies in humans facilitating the accumulation of evidence across all assessments. The approval of biosimilars follows detailed regulatory pathways derived from those of their reference products and established by agencies such as the European Medicines Agency and the US Food and Drug Administration. Regulatory authorities impose requirements to ensure that biosimilars meet high standards of quality, safety, and efficacy and are highly similar to their reference product. Purpose: This review aims to aid clinical understanding of the high standards of development, manufacturing, and regulation of biosimilar insulins. Methods: Recent relevant studies indexed by PubMed and regulatory documents were included. Conclusions: Driven by price competition, the emergence of biosimilar insulins may help expand global access to current insulin analogues. To maximize the impact of the advantage for falling retail costs of biosimilar insulins compared with that of reference insulins, healthcare professionals and insulin users must gain further awareness and confidence.