Insulin was discovered in 1921 and soon became widely available in high-income countries. However, many people currently in need of this life-saving medicine are unable to access it. This is a global phenomenon, impacting not only populations of low- and middle-income countries but low-income populations in the U.S. In the U.S., the rate of diabetic ketoacidosis remains high in certain subpopulations, the cost of insulin being the main precipitating factor. On a global level the main cause of mortality for a child with type 1 diabetes is a lack of access to insulin, and in sub-Saharan Africa the life expectancy of a child with type 1 diabetes can be as low as 1 year. One lens for considering the issue of access to health and medicines is to consider society as a three-legged stool. In this paradigm, the role of the public sector is to provide "protections" to the population it serves; the private sector is made up of "responsible businesses" that supply many of the goods and services people need; and the plural sector comprises communities and not-for-profits providing the "social affiliations" that are needed. For HIV/AIDS, each of these "legs" played a role in improving access. Civil society raised awareness of the issue and advocated for access to treatment. Governments provided funding and responses both nationally and globally. Finally, the private sector played its role, under pressure from civil society and governments, in lowering the price of medicines and developing programs to expand access. Here, we use this framework to describe the shortcomings in access to insulin from a U.S. and global perspective.