Novo Nordisk (the maker of the newest insulin Levemir) spends about 17.8b kroner a year on R&D (or about 12.6% of their revenue). Levemir was introduced in 2005; they've long since made up any R&D costs. The first synthetic insulin (Humulin) is from 1978. These aren't new medications, even Lantus is over 20 years old. The R&D costs don't factor into the price they charge at this point.