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Pre-diabetes: Do current screening guidelines work?

10/17/2016

Approximately 21 million Americans have diabetes, the seventh leading cost of death in this country. Diabetes raises the risk of heart disease, stroke, blindness and kidney disease but early diagnosis of type 2 diabetes can prompt lifestyle changes that can control or ward off possible complications.

Some organizations, including the American Diabetes Association and the World Health Organization have established metrics for the diagnosis of prediabetes, a condition where blood glucose levels are higher than normal but not yet high enough for a diabetes diagnosis. Others have supported a web-based risk model to define who is at high risk for prediabetes.

In the October 3, 2016 edition of JAMA Internal Medicine, Saeid Shahraz, MD, PhD and researchers at Tufts Medical Center report that current ways to evaluate prediabetes are flawed, and may lead to misdiagnosis and unnecessary testing. Dr. Shahraz answers questions about the study below:

What guidelines or metrics are currently used to diagnose prediabetes?

The American Diabetes Association (ADA) has set up a lower cut point for diagnosing prediabetes (those with Impaired Fasting  Glucose 100 mg/dL) compared to the World Health Organization's cut point, which is 110 mg/dL. This arbitrariness in cut point definition triples the number of cases labeled as prediabetes. Along with lowering the diagnostic threshold by the ADA, the Centers for Disease Control and Prevention (CDC), the American Medical Association (AMA), and the ADA endorsed and advertised a web-based risk model to define high-risk population for prediabetes. The risk engine asks a few questions (age, sex, family history of diabetes, history of gestational diabetes and high blood pressure, physical activity and weight) and outputs a score that defines if the person is at risk for prediabetes. We suspected that the risk engine might overestimate the risk.   

What were your major findings?

The results were surprising. Using the web-based risk model, 3 out of 5 people 40 years or older and 8 out of 10 people 60 or older are at high risk for prediabetes. While it’s important to properly identify people with prediabetes so they may make lifestyle changes to prevent the disease from developing, the tool used to identify those at high risk must be accurate. We believe the web-based tool is not helpful, as it casts too wide a net and may lead to unnecessary testing and worry.

What should consumers take away from the findings? 

For people: If the risk engine classifies them as being high-risk for prediabetes, they should not worry that much about the risk, as it might be a false result. In other words, there is a good chance that their blood sugar result shows normal. They should check with their physician. For professional decision makers and researchers: it's important to specify and calibrate a risk model that reasonably classifies populations for a specific medical condition.   

For now, how should prediabetes be diagnosed?

Being diagnosed with prediabetes is a wake-up call to make lifestyle changes – such as proper diet and exercise which helps control weight and set high blood sugar levels back to normal or near normal. Primary care physicians have enough knowledge to detect prediabetes in higher-risk patients through routine blood check-ups. Until we have a risk test that properly identifies an at-risk population, a regular physical exam with your doctor is the best bet for determining your chance of prediabetes.