Laura Ungar, USA TODAY9:47 a.m. EDT September 15, 2014

Americans are getting fatter, and older. These converging trends are putting theUSAon the path to an alarming health crisis: Nearly half of adults have either pre-diabetes or diabetes, raising their risk of heart attacks, blindness, amputations and cancer.

Federal health statistics show that 12.3% of Americans 20 and older have diabetes, either diagnosed or undiagnosed. Another 37% have pre-diabetes, a condition marked by higher-than-normal blood sugar. That’s up from 27% a decade ago. An analysis of 16 studies involving almost 900,000 people worldwide, published in the current issue of the journal Diabetologia, shows pre-diabetes not only sets the stage for diabetes but also increases the risk of cancer by 15%.

“It’s bad everywhere,” says Philip Kern, director of the Barnstable Brown Diabetes andObesityCenterat theUniversityofKentucky. “You almost have the perfect storm of an aging population and a population growing more obese, plus fewer reasons to move and be active, and fast food becoming more prevalent.”

Tabitha Jordan ofLouisvillesays she was eating poorly, struggling to find time for exercise and packing on pounds when her doctor diagnosed pre-diabetes in October. She recognized the danger; she’d seen her mother go blind, lose toes and eventually die from diabetes complications at age 63.

“It was kind of like, ‘It’s time for me to do something,’ ” saysJordan, 47. “I knew things had to change.”

Doctors and experts coined the name pre-diabetes in the late 1990s, replacing less worrisome terms such as “borderline diabetes” that didn’t convey the seriousness of the condition. Without lifestyle changes, the U.S. Centers for Disease Control and Prevention says up to 30% of people with pre-diabetes develop Type 2 diabetes within five years.

Pre-diabetes often has no symptoms; it’s found through blood tests. But most of the time it remains undiagnosed. The CDC says about 10% of the 86 million afflicted adults know they have it.

Jordan, who was diagnosed through an A1C blood test, faced several risk factors: She was over 45, had diabetes in her family and consumed a diet heavier on convenience foods and meat-and-potatoes than fruits and vegetables. She also lives in one of 15 hard-hit states concentrated in the South considered part of a “diabetes belt.”

And she counted herself among the two-thirds of Americans who are overweight or obese – she was 78 pounds heavier than she is today.

As pre-diabetes rises, experts are pushing for greater awareness and screening. Research shows programs promoting lifestyle changes can reduce the risk of Type 2 diabetes by almost 60% – helping save lives and money. Diabetes cost the nation $245 billion in 2013, according to the Alexandria, Va.-based American Diabetes Association.

“We’ve proven (pre-diabetes) is an intervention time,” said Matthew Petersen, the association’s managing director of medical information and professional engagement. “It’s a call to action.”

Pre-diabetics can prevent or delay diabetes by losing 5%-7% of body weight; getting at least 150 minutes a week of moderate exercise such as brisk walking; and eating a moderate-calorie, healthy diet, experts say.

“It’s very clear that weight loss is far more powerful than any drug we can give,” Kern says.

Jordantook a diabetes prevention class at the YMCA of Greater Louisville and now eats better and works out six days a week. A recent blood test revealed she is no longer pre-diabetic.

Doctors acknowledge others can take similar steps, but worry many won’t, since it’s so hard to change ingrained lifestyles.

“What we are heading toward is much higher health care costs and much more disability,” said Sathya Krishnasamy, an endocrinologist withUniversityofLouisville Physicians. “We need to make major, drastic changes as a community and as a nation.”