In 2009, the body that accredits medical schools issued a new requirement: All medical schools must implement policies that help them attract and retain more diverse students. Failure to do so can lead to citations from this body, the Liaison Committee on Medical Education, and can affect their status as accredited institutions.
This effort appears to be working. In a research letter published today in JAMA, researchers examine the changing demographics of medical students from 2002 to 2017. They found an increase in diversity in enrollment, especially since 2012, which the researchers think may be the first year new standards could be expected to have an effect.