An oligopoly colluding to push the price of easily produced products into the stratosphere isn't a product of
deregulation. In a
deregulated or
under-regulated market, thousands of cottage-industry insulin producers would be competing to shave pennies off the prices of their insulin. You might have a hard time finding
safely produced insulin, but you wouldn't have a hard time finding
cheap insulin.
Oligopolies colluding to elevate prices of necessities to fatal levels is a product of regulation. In cases like these, incumbent businesses support regulation because it raises barriers to entry for new entrants; this results in oligopoly or monopoly, permitting the extraction of monopoly rents, even when people are literally dying in the streets because they can't afford products like insulin which are extremely cheap to produce.
(Insulin wasn't always cheap to produce, but for 43 years now it's produced by genetically engineered microorganisms, which makes it very cheap. It's a tiny protein, only 51 amino acids, produced from a 110-amino-acid precursor protein.)