Two U.S. lawmakers called on federal antitrust regulators to probe whether four companies tried to set prices for insulin and other diabetes drugs. The request by Senator Bernie Sanders and Congressman Elijah Cummings follows a similar letter they sent last fall, calling for an investigation into 14 drug companies over generic drug price increases. Sanders and Cummings raised questions about sky-rocketing prices for insulin and used a chart showing that many of the price spikes occurred in tandem. They noted that the original patent on insulin, which is a hormone used by diabetics to control blood sugar levels, expired 75 years ago.