While being overweight or obese has long been associated with type 2 diabetes, one third of normal weight people may have prediabetes, according to a new study published in the Annals of Family Medicine.
The study found that the prevalence of prediabetes increased markedly in the 18 years since 1988 among individuals with a body mass index in the healthy range (18.5 to 24.99).
The report, which was conducted at the University of Florida, analyzed data from the National Health and Nutrition Examination surveys from 1988-1994 and 2009-2012. Researchers found that among healthy weight adults, age 20 years or older without diagnosed or undiagnosed diabetes, prediabetes increased from 10 percent in 1998-1994 to 19 percent in 2012. Among those 45 years or older, the prevalence of pre-diabetes increased from 22 percent to 33 percent.
According to the CDC about one in three people in the U.S. has prediabetes. A diagnosis of prediabetes means having a blood sugar level higher than normal, but not high enough for a diagnosis of diabetes, with a hemoglobin A1C reading—the average blood sugar levels over 2 to 3 months—of 5.7 to 6.4 percent.1
Without lifestyle changes to improve their health, it is estimated that 15 to 30 percent of people with prediabetes will transition to type 2 diabetes within five years. However, for those at the lower end of the A1C scale, the risk drops.2
Research shows that people with prediabetes can lower their chances of developing type 2 diabetes by 58 percent by exercising and lowering their body weight by 5 to 7 percent.3
Current guidelines from the U.S. Preventive Service Task force (issued October 2015) recommend that people between the ages of 40 and 70 years of age be screened for diabetes if they are overweight or obese. In contrast, the American Diabetes Association advises screenings for every adult over 45, with greater emphasis on those who are overweight or obese or have other co-morbidities.
The study notes that following these prevention efforts would ignore a large number of healthy weight people with prediabetes.
In a related finding from Northwestern University, about 55 percent of high- risk individuals for diabetes or pre-diabetes were missed under the current government guidelines. Some say this calls the guidelines into question.
“Basically, there are healthy weight people with pre-diabetes who aren’t being detected and treated,” said Arch G. Mainous III, PhD, chair of the Health Services Research, Management & Policy department and lead author of the Florida study. “Many doctors may not view people in the healthy weight group as metabolically unhealthy. This new research might change how we see the patient population that walks into the office and make us realize that overweight or obesity might not be the prime risk factor to determine screening.
“For people who don’t think they’re going to be affected by diabetes, people who are sedentary, people who say, ‘I weigh the same as I used to, but I’m soft,’ this could be a wake up call,” said Mainous.
Since these individuals are not technically overweight, Mainous suggests weight-bearing exercise targeting “skinny fat” to help prevent transitioning to type 2 diabetes. (To put it simply, muscle is a better metabolizer of the sugar in your body than fat—it’s more efficient and requires less insulin to be used.)
“Many times we are looking at people who need to build more muscle rather than losing weight,” he said.
One question is whether the cut off numbers for prediabetes are too low, making greater numbers of people subject to the diagnosis.
“We have to draw line in the sand,” said Kevin Furlong, MD, an endocrinologist and associate professor of clinical medicine at Thomas Jefferson Hospital in Philadelphia. “Someone who has a 6.2 or 5.7 is not normal, but is it worth creating anxiety or stress in the patient? If we call it prediabetes, we make people take it more seriously and maybe get them to embark on a healthy lifestyle. Is that a bad thing?”
The Florida study relied on hemoglobin A1C values to diagnose prediabetes. When it comes to these results, Mark Schutta, MD, the medical director of the Penn Rodebaugh Diabetes Center at the University of Pennsylvania, urged caution.
“While most lab values are very good and very reproducible, there are factors, such as hemoglobinopathies (genetic blood disorders) and other things that change the binding of glucose to red blood cells that could make someone’s A1C be reported as higher than normal,” he said.4
This is particularly true for patients of African, Mediterranean or South Asian descent.5
“Also, a lot of people don’t live in the normal range,” said Schutta.
For patients at high risk of developing type 2 diabetes, early detection can help prevent later complications, said Schutta. But if he found someone with prediabetes who he thought had a relatively low chance of transitioning to type 2 based on other risk factors, he might recommend an oral glucose tolerance test, “which I think might be a little more sensitive.”
“With all the screening going on we’re picking up lots of folks that probably during the course of their lifetime are not going to develop type 2 diabetes,” he said.