A nurse in 1938 checks the amount of insulin in a needle. For many decades, the only insulin available to people with diabetes came from the pancreases of cattle or pigs. Insulin from animals is still available outside the U.S. — and cheaper than a recombinant DNA version. Bettmann/Corbis hide caption

itoggle caption Bettmann/Corbis

Laura Zakhar connects her son, Kevin, 15, to the "feedbag" that contains his nutrition. Lately, Zakhar has had trouble getting the calcium solution Kevin needs, in part because hospitals have been reserving limited supplies for patients who need it even more desperately than he does. Elizabeth Larkin for NPR hide caption

itoggle caption Elizabeth Larkin for NPR