Rates of prediabetes have risen sharply in England, and without intervention, the nation may experience a steep increase in diabetes in the coming years, according to University of Florida researchers working with the University of Leicester in England.

Prediabetes rates among English adults rose from about 12 percent in 2003 to 35 percent in 2011, according to the findings of a study published in BMJ Open.

"The rapid rise was exceptionally surprising and suggests that if something doesn't happen, there is going to be a huge increase in the prevalence of diabetes," said Arch G. Mainous III, Ph.D., the study's lead author and chair of the department of health services research, management and policy at UF's College of Public Health and Health Professions.

Prediabetes is defined as having blood glucose concentrations higher than normal, but not high enough for a diabetes diagnosis. People with prediabetes have a greater risk than people with normal blood glucose levels of vascular problems, kidney disease, and nerve and retinal damage. Each year, between 5 and 10 percent of people with prediabetes will develop diabetes.

"We know that prediabetes is a major risk factor for developing diabetes," said Mainous, the Florida Blue endowed chair of health administration. "We also know that interventions in the form of medications or lifestyle changes are successful in preventing diabetes. It's a lot better to stop diabetes before it develops."

For the UF study, researchers analyzed data collected in 2003, 2006, 2009 and 2011 by the Health Survey for England. Sponsored by the Information Centre for Health and Social Care and the Department of Health, this population-based survey combines questionnaires with physical measurements and blood tests. The researchers classified survey participants as having prediabetes if they had a blood glucose level between 5.7 and 6.4 percent, which the American Diabetes Association considers prediabetes, and if they indicated they had not previously been diagnosed with diabetes.

The 2011 data showed that 35 percent of English adults and more than 50 percent of adults age 40 and older who were overweight had prediabetes. People with lower socioeconomic status were at substantial risk for having prediabetes.

England's prediabetes rates are similar to those in the United States, where 36 percent of adults are estimated to have the condition, but England's rates climbed more steeply than the United States' over a similar time period. While the exact cause for the rapid rise is unknown, it may be linked to increases in obesity in England in the late 1990s. Metabolic changes associated with weight gain may take several years to develop.

"The study is an important signal that we need to take action to improve our diet and lifestyles," said study co-author Richard Baker, M.D., a professor of quality in healthcare at the University of Leicester department of health sciences. "If we don't, many people will have less healthy, shorter lives."