A drug that's used to help control blood sugar in people with diabetes has now been shown to help prevent or slow kidney disease, which causes millions of deaths each year and requires hundreds of thousands of people to use dialysis to stay alive.

Doctors say it's hard to overstate the importance of this study, and what it means for curbing this problem, which is growing because of the obesity epidemic.

The study tested Janssen Pharmaceuticals' drug Invokana. Results were discussed Sunday at a medical meeting in Australia and published by the New England Journal of Medicine.

About 30 million A...