U.S. Senator Chuck Grassley requested detailed information on UnitedHealth's Medicare billing practices in a letter to CEO Andrew Witty, amid reports suggesting the insurer may have leveraged billing rules to its advantage.

The Iowa Republican’s letter to the company cites findings from a series of Wall Street Journal articles.

Senator Chuck Grassley has raised alarm over reports of a probe by the Justice Department into UnitedHealth's Medicare billing practices. The Iowa Republican called out the company in a letter, stating that its practices have harmed both people under Medicare Advantage plans and American taxpayers.