More adults have prediabetes, with patients (and often physicians) unsure who's at risk

Washington -- There's a vast difference between the number of people the public health community places on the road to type 2 diabetes and the number of individuals who say they are aware of their perilous journey.

As many as a fourth of U.S. adults, or 54 million people, have prediabetes, according to the Centers for Disease Control and Prevention. However, just 4% of those who responded to a large CDC survey said they had been told they have this newly defined condition, which presents with impaired fasting glucose or impaired glucose tolerance or both. The findings are in the Nov. 7 Morbidity and Mortality Weekly Report.

Taking a "glass is half full" stance, the CDC and several physicians view this startling gap as an educational opportunity. After all, they note, the progression to type 2 diabetes isn't inevitable. Actions can be taken to keep the disease at bay.

Without increasing physical activity and shedding extra pounds, though, the millions of people with prediabetes are five to 15 times more likely to develop type 2 diabetes than are people with normal glucose values, according to the CDC. The agency estimates that unless steps are taken, approximately one out of every three people born in 2000 will develop diabetes in his or her lifetime.

"I want to emphasize that there is a lot that can be done to reduce the risk of developing diabetes," said Deborah Rolka, a statistician for the CDC's Division of Diabetes Translation who authored the MMWR article.

For example, the federal Diabetes Prevention Program found that making lifestyle changes could dramatically reduce the risk of developing type 2 diabetes. "We know that it takes about 30 minutes of walking five days a week, and it can reduce the risk of going on to diabetes by about 60%," said William Herman, MD, MPH, director of the Michigan Diabetes Research and Training Center at the University of Michigan Health System.

The AMA also provides advice to physicians who are helping patients lower their risk for the disease.

Among the possible reasons for the low risk awareness is that people are not being tested, Rolka suggested. She noted that prediabetes is a relatively new term, and its significance has been recognized only recently.

The CDC defines the condition as an impaired fasting glucose of 100 mg/dL to 125 mg/dL, an impaired glucose tolerance of 140 mg/dL to 199 mg/dL, or both.

"It's very much in the patient's best interest and in national health care's best interest for people to know if they are on this path," said Matt Petersen, director of the American Diabetes Assn.'s Information Resources. "There is a very significant potential public health impact here if you can improve that 4% [knowledge rate] to more than 50%."

Bridging the knowledge gap

Just how this gap emerged is likely due to the fast pace of the emerging science surrounding prediabetes, said several physicians. The group of patients to test is a moving target, and conflicting screening recommendations are making it difficult for physicians to zero in on the right patients.

The American Diabetes Assn. takes an aggressive approach and recommends including all patients with a body mass index equal to or greater than 25 kg/m and who have various risk factors. The ADA also recommends screening everyone older than age 45. However, the U.S. Preventive Services Task Force recommends screening patients whose blood pressure is greater than 135/80 mmHg.

"It's likely that more patients would be screened if the recommendations were made clearer," said Todd Brown, MD, an assistant professor in the Division of Endocrinology and Metabolism at Johns Hopkins School of Medicine in Baltimore.

Dr. Brown generally screens patients who are older, overweight or have a family history of the disease. He tends to first do an IFG test and follow with an IGT test if necessary.

But then another problem looms. Patients need to fast before taking an IFG, but since most people schedule appointments for acute care, it's not likely they have been fasting. That, however, could change if a trend toward screening patients using A1c measures catches on, said Dr. Brown.

The fact that the criteria for prediabetes changed a few years ago and now target people with lower fasting glucose levels means many more people are considered at higher risk for type 2 diabetes than had been previously, said Dr. Herman. But some physicians may not even be aware that the cut point for prediabetes has dropped to a fasting glucose level of 100 to 125 mg/dL. "So there are two issues. There are a lot more people than there were under the old criteria, and awareness is lagging behind."

In an effort to ease the decision-making process, a study was recently released on a new assessment tool designed to help determine which patients to screen. The Tool to Assess Likelihood of Fasting Glucose Impairment, or TAG-IT, was developed by Richelle Koopman, MD, an assistant professor of family medicine at the University of Missouri, and colleagues from the Medical University of South Carolina in Charleston.

The study is in the November/December Annals of Family Medicine.

TAG-IT uses six readily obtainable identifiers: age, sex, body mass index, family history of diabetes, heart rate (beats per minute) and hypertension.

The tool makes it easier to assess the combination of risk factors each patient presents, said Dr. Koopman. "Should a 22-year-old college athlete with a BMI of 26 kg/m and a family history of diabetes be tested? Should a 35-year-old sedentary woman be tested even though her BMI is 23 kg/m?"

The researchers found that TAG-IT represented an improvement over lists of risk factors and over BMI alone in identifying patients with IFG.

"Anything we can do to help identify people is going to be helpful to primary care physicians. And that is my perspective as a primary care physician," said Dr. Koopman.