Over the past two decades, the rate of kidney failures among Native Americans quietly dropped a total 54 percent. That’s the word this month from the Centers for Disease Control. The milestone is remarkable considering Native Americans are more likely to have diabetes than any other group, and diabetes is the major cause of kidney failure. It didn’t require a magic pill or miracle cure. Health officials credit a sustained, concerted effort. The low-key success story is saving lives and millions of dollars.