On the shelves are three insulin pumps: one with a 5-year warranty, one at a bargain barrel price that comes with no warranty, and one accompanied by a written offer allowing you to obtain the source code (and, subject to the terms of the GPL, prepare your own derivative works) at no additional charge any time within the next three years.
Weighing your options, you go with pump #3. You write to the company asking for the GPL source. They say "nix". They're in breach.