One in every three Americans has prediabetes — blood sugar levels that are elevated, but not high enough to be considered a marker of diabetes.

That’s the upshot of a new study, by researchers from the University of California-Los Angeles, that also estimates that nearly half of California adults have prediabetes or undiagnosed diabetes, WIVB TV reports. 

Nearly three out of four people with prediabetes will eventually develop diabetes, but it can be stopped by losing weight through exercise and eating a healthy, low-carb and low-sugar diet, experts note.

“The rates are very high, surprisingly high,” said researcher Susan Babey, who co-authored the report. “We’re very concerned about the rates among the young adults because of their increased risk of developing Type 2 diabetes, which sets them on this path for some serious complications in the future.”

Complications of diabetes include blindness, heart and kidney disease, and premature death, the researchers noted.

The Centers for Disease Control and Prevention estimate that 90 percent of people with prediabetes do not know they have it, but a simple blood test can quickly make the diagnosis.