Biosimilar insulins are likely to enter the market of diabetes therapies as patents for major branded insulin products start to expire in the next few years (on June 2014, the European Medicines Agency authorized the first biosimilar of insulin glargine, Abasria, 100 Units/ml, for the treatment of diabetes mellitus). This would allow providing comparable clinical benefits of the current available insulins at a significantly lower cost, thus increasing the affordability and access of insulin treatment for patients with diabetes. Biosimilars are approved via a stringent regulatory pathway demonstrating quality, safety, and efficacy comparable to the reference product. However, the production complexities of such products raise important considerations for treatment efficacy and patient safety, including naming and product tracking, substitution practices, and pharmacovigilance. Additionally, as practitioners' knowledge regarding the differences about pharmacological, clinical, and regulatory aspects between biosimilars and generic small molecules is often suboptimal, specific education on biosimilar prescribing, dispensing, and administering is critical for ensuring patients' benefit and safety. This article discusses all the issues concerning biosimilar, especially biosimilar insulins.