Is Web-Based Test Labeling Too Many People With 'Prediabetes'?

Miriam E Tucker

October 04, 2016

New research shows that a majority of US adults over age 40 are at risk for prediabetes, according to an online risk calculator, but the investigators question whether so many people should receive the diagnosis.

The findings were published online October 3 in a research letter in JAMA Internal Medicine by Saied Shahraz, MD, PhD, and colleagues, of Tufts Medical Center, Boston, Massachusetts, and are based on use of the online risk instrument "Do I Have Prediabetes?" endorsed by the American Diabetes Association (ADA), the American Medical Association (AMA), and the Centers for Disease Control and Prevention (CDC).

When applied to the US population, that instrument identifies three of five among those aged 40 and older, and eight of 10 over-60-year-olds who don't already have diabetes as being at risk for prediabetes. The tool encourages those individuals to talk to their doctors about laboratory glucose testing, in line with screening guidelines.

But Dr Shahraz and colleagues question the value of that process.

"We showed that the online risk test endorsed by ADA, AMA, and CDC is identifying and medicalizing a very large at-risk population, which can lead to overutilization of resources," Dr Shahraz and coauthor David M Kent, MD, wrote in an email to Medscape Medical News.

"We also note that even among those confirmed to have prediabetes, a substantial proportion are still at relatively low risk of progression to diabetes and at very low risk of end-organ damage," they add.

They cite as problematic the 2010 ADA guidelines that reaffirmed the prior widening of the definition of prediabetes by lowering the fasting blood glucose cutoff to 100 mg/dL from the previous 110 mg/dL and allowing the use of HbA1c for diagnosing prediabetes (cutoff 5.7%).

"This expansion increased the at-risk population twofold. Still, evidence favoring the long-term benefits of the definition change is very poor," the two investigators say.

And in an accompanying Editor's Note, JAMA Internal Medicine editor and cardiologist Rita F Redberg, MD, writes that Dr Shahraz and colleagues "elegantly demonstrate how common conditions can be 'medicalized' " and points out that prediabetes is "a condition never heard of 10 years ago.

"We suggest a better approach to preventing the epidemic of obesity and its multiple health-related complications is emphasis on healthful diet, weight loss when appropriate, and increased physical activity at all levels — by schools, the medical profession, and public-health and governmental agencies," Dr Redberg writes.

"Medicalizing" Too Many?

In their study, Dr Shahraz used data from nearly 10,000 participants in the 2013–2014 National Health and Nutrition Examination Survey (NHANES) population older than 18 years without type 2 diabetes and calculated prediabetes risk scores based on the answers to seven questions that closely matched those in the risk screening instrument:

  1. How old are you?

  2. Are you a man or a woman?

  3. If you are a woman, have you ever been diagnosed with gestational diabetes?

  4. Do you have a mother, father, sister, or brother with diabetes?

  5. Have you ever been diagnosed with high blood pressure?

  6. Are you physically active? ("Physically active" was ascertained by answers to a further five questions regarding activity at certain intensity levels.)

  7. What is your weight status?

Patients receiving a score of 5 or more are deemed at high risk for prediabetes and are advised by the instrument to visit their physician for a blood glucose test.

Among the 3815 NHANES participants aged 40 years or older, 58.7% were identified as being at high risk for prediabetes. For the 1841 older than 60, the weighted proportion at high risk for prediabetes was 80.8%.

In their discussion, the authors point out that there is no direct evidence that type 2 diabetes prevention alters the risk for diabetes-related complications.

Moreover, they say, progression to type 2 diabetes would likely be slower among those who qualify based on either HbA1c or fasting blood glucose as opposed to those who meet criteria based on an oral glucose tolerance test.

And Dr Shahraz and Dr Kent told Medscape Medical News that prior work from their group reanalyzing the landmark Diabetes Prevention Program — which showed that intensive lifestyle modification or metformin can prevent or delay the onset of diabetes in people with prediabetes — revealed that most of the benefit of these interventions can be captured by targeting just those individuals at especially high risk of progressing (BMJ. 2015;350:h454).

"This is important, since it is estimated that 80 million people have prediabetes. The resources that it would take to identify and treat all these people are potentially overwhelming."

The authors have no relevant financial relationships.

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JAMA Intern Med. Published October 3, 2016. Article, Editorial

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