For decades, more and more Californians have put on weight and fallen sick with diabetes, prompting warnings that the disease was spiraling out of control.
Now experts have data showing just how bleak the situation is.
Researchers from UCLA determined that 55% of California adults have either diabetes or pre-diabetes, a condition in which blood glucose levels are higher than normal but not high enough to be considered diabetic, according to a study published Thursday.
Experts already knew that about 9% of people in the state have diabetes. But previous estimates had put the rate of pre-diabetes at about 33%, lower than the 46% calculated by UCLA researchers.
"Our genes and our environment are kind of on a collision course," said Dr. Francine Kaufman, the former head of the American Diabetes Assn., who was not involved with the research. "It's not stopping."
Rates of diabetes have increased more than 175% nationally since 1980, according to federal data. It's now the seventh-leading cause of death in California.
The UCLA researchers used data from the National Health and Nutrition Examination Survey to create a model that predicts pre-diabetes, based on factors such as race, height and weight. That model was then applied to data from the California Health Interview Survey, determining that 13 million adults in the state have either pre-diabetes or undiagnosed diabetes.
Up to 70% of those with pre-diabetes develop diabetes in their lifetime.
"This study is a barometer that's telling us that the storm is coming," said Harold Goldstein, head of the California Center for Public Health Advocacy, a nonprofit that supports public health initiatives and funded the study.
Already, 2.5 million Californians have been diagnosed with diabetes, which can cause kidney failure, amputation and premature death. More than 100 diabetic Californians lose a leg, foot or toe every week because of the disease, according to state data.
But experts say there's hope of curbing the disease's spread. The vast majority of diabetes cases in California — upward of 90% — are Type 2, which is preventable. People can stave off developing diabetes by adopting a healthier diet and increasing physical activity, experts say.
The difficulty is that most people don't take action until it's too late.
"One of the biggest problems with pre-diabetes is that most people don't know they have it," said Dr. Susan Babey, the paper's lead researcher and a co-director of the Chronic Disease Program at the UCLA Center for Health Policy Research.
About 90% of people with pre-diabetes are unaware of their condition, so most don't get any treatment, said Matt Petersen, managing director of medical information for the American Diabetes Assn. There are no symptoms of pre-diabetes, which can be detected only through blood tests.
"If you do intervene, you have a successful outcome," he said. "We just have to have people know they're at risk and get screened."
An often-cited clinical research study found that people with pre-diabetes who were overweight and improved their diet and worked out reduced their diabetes risk 58%. Those who instead took a medicine to treat diabetes reduced their risk only 31%.
The UCLA researchers found that pre-diabetes in California increases with age, from 33% of adults ages 18 to 39 having the condition to 60% in those 55 to 69.
They also found racial and ethnic variation in the rates. About 42% of Asian adults have pre-diabetes, 44% of Latino adults, 48% of white adults, 50% of African American adults and 55% of Pacific Islander adults.
Goldstein says he thinks the high rates of pre-diabetes, especially among younger generations, arise from sedentary lifestyles and unhealthy eating habits. "They've grown up in a world that's designed for the disease," he said.
He wants to increase access to healthy, fresh foods, and reduce junk food advertising. On Tuesday, California state legislators proposed a "health impact fee," which would tax sugar-sweetened beverages by 2 cents an ounce. Bob Achermann, executive director of the California Beverage Assn., on Wednesday called the measure the latest in a series of "misguided tax proposals on sugar-sweetened beverages," and urged leaders to "find real solutions to obesity and diabetes."
In 2014, Berkeley voters approved the nation's first citywide tax on sodas and other sugary beverages.
Kaufman, a pediatrician and endocrinologist, agreed that soda and fast food are a problem.
When she began her medical training at Children's Hospital Los Angeles in 1975, she almost never had young patients with Type 2 diabetes. Now she sees children with the disease regularly.
She said the state needs to target the causes of the obesity and diabetes epidemics with the same vigor it did tobacco usage several decades ago. The work that's been done in California so far hasn't done much to stop the increase in diabetes cases, she said.
"It just isn't enough to make any kind of dent," she said.