Human insulin was discovered as a treatment for diabetes approximately 100 years ago and has been on WHO's Model List of Essential Medicines since the first list was published in 1977. In spite of this, current insulin prices and availability pose a barrier to treatment in most low- and middle-income countries (LMIC). In higher-income countries, several sub-populations cannot reliably access this lifesaving medication since it is unavailable, unaffordable or both. As stated in the WHO Model List of Essential Medicines, insulin is used principally to treat diabetes. Insulin biotherapeutic products (BTPs), and the corresponding similar biotherapeutic products (SBPs), have been selected for this WHO pilot procedure because:

• insulin is a life-saving medication
• current insulin prices pose a barrier to treatment in most LMIC
• established WHO technical guidance exists for evaluation of biotherapeutic protein products prepared by recombinant DNA technology and on evaluation of SBPs.

Given that BTPs, including their corresponding SBPs, are complex and that the regulatory assessment of those products according to internationally acceptable guidelines and standards can be challenging in some countries, WHO has developed a WHO pilot procedure for prequalification of human insulin, following either one of two pathways:

• full assessment of human insulin BTPs, or the corresponding SBPs, that have not been registered by stringent regulatory authorities (SRAs) (referred to as "full Assessment")
• abridged assessment of human insulin BTPs, or the corresponding SBPs, that have been approved by an SRA and marketed in the country of registration (referred to as "abridged Assessment").

Full assessment will include, among other requirements WHO’s inspection of the relevant manufacturing facilities and clinical research sites, based on information submitted by the manufacturer of such products. Evaluation and inspection is based on WHO-recommended technical standards and guidance. Based on the experience gained during the pilot process, WHO may revise the prequalification procedure for human insulin accordingly.