At Robert F. Kennedy Jr.’s confirmation hearings, beginning on Wednesday, senators are expected to question him closely about his controversial views on vaccines.

For years Mr. Kennedy has questioned the safety of vaccines, including those for polio and measles, two diseases that continue to harm children. More recently, he has said that he’s not planning to take vaccines away from Americans but wants to release safety data to the public — even though nearly all of the data is already publicly available.

Mr. Kennedy’s contrarian views extend well beyond vaccines. And as secretary of health and human services, he would have enormous influence on health policy, even on issues typically under state control, by cutting funding for certain programs or elevating others.

Here’s a fact check of some of his claims.

What was said

This is false. Mr. Kennedy’s number is off by orders of magnitude.

The National Diabetes Statistics Report estimated that in 2021, about 35 per 10,000 children and adolescents younger than 20 — that is, 0.35 percent — had a diagnosis of diabetes. Another study found that 0.1 percent of young people 10 to 19 had diabetes in 2017.