Hagedorn created NPH insulin and founded Nordisk Insulinlaboratorium, known today as Novo Nordisk. NPH insulin is one of the earliest examples of engineering drug delivery.

Hagedorn became interested in modifying the sbsorption rate of insulin. He was aware that contaminating proteins slowed the aborption of insulin into the bloodstream, but these caused irritation and side effects. Searching for a protein that would not cause any irritation, he came upon protamine, a protein isolated from fish sperm. Hagerdorn discovered that the addition of protamine to insulin caused the insulin to form microscopic clumps. These clumps took longer to dissolve in the bloodstream. With B. N. Jensen, N. B. Krarup, and I. Wodstrup,