(HealthDay News) — Despite the widespread availability of generic drugs, insulin has shown that generics are not an automatic phase in the life cycle of a drug, according to an article published in the New England Journal of Medicine.

Jeremy A. Greene, MD, PhD, and Kevin R. Riggs, MD, MPH, from the Johns Hopkins University School of Medicine in Baltimore, discuss the reasons why insulin is unavailable in generic form and is associated with out-of-pocket costs for uninsured patients ranging from $120 to $400 per month.

The authors note that the history of insulin hasn’t followed the standard chronology of pharmaceutical innovation, in which patent monopolies give way to generic competition. Rather, insulin has evolved through incremental improvements. Subsequent iterations represent innovations in terms of safety, efficacy and convenience. 

The re-patenting technique known as “evergreening,” which extends the life of a product after initial patent expiration, has been applied to insulin, with real advantages seen in cascading generations of insulin products.

“The history of insulin highlights the limits of generic competition as a public health framework,” the authors wrote. “Nearly a century after its discovery, there is still no inexpensive supply of insulin for people living with diabetes in North America, and Americans are paying a steep price for the continued rejuvenation of this oldest of modern medicines.”


  1. Greene JA, Riggs KR. N Engl J Med. 2015;372:1171-1175.