Prediabetes: Overhyped?

July 23, 2014

The statistics are alarming: According to a recent study[1], 35% of adults in England had prediabetes[2] in 2011, up from just 12% in 2003. The situation in the United States is no better: The American Diabetes Association (ADA) estimates that[3] 37% of American adults had prediabetes in 2012, including 51% of adults ages 65 and above. But what exactly does it mean to have prediabetes? A new article suggests that this diagnosis is overhyped and should probably be scrapped.

Published in the medical journal BMJ, the article[4] — written by two professors of medicine, one British and one American — asserts that the definition of prediabetes has become too broad to be useful. According to a report on the article[5] at Medical News Today, the authors considered whether a diagnosis of prediabetes has been shown to improve any health outcomes. They found that while treatments for prediabetes (usually dietary changes and exercise, but sometimes also the drug metformin[6]) delayed the onset of Type 2 diabetes[7] by a few years in many cases, there was no evidence of long-term health benefits resulting from a diagnosis of prediabetes. In fact, the ADA is the only medical organization that provides criteria for diagnosing prediabetes — both the World Health Organization (WHO) and Britain’s standard-setting body, known as NICE, do not recognize prediabetes as a condition and discourage the use of the word. However, due to the ADA’s worldwide influence, doctors and researchers around the world have been examining prediabetes using the ADA’s guidelines.

As the authors of the article note, the ADA’s current guidelines for diagnosing prediabetes are quite new, adopted only in 2010. The first category of “sub-diabetes,” called impaired glucose tolerance, was created in 1979 and was defined as a result of 140–200 mg/dl from an oral glucose tolerance test[8] (with higher than 200 mg/dl indicating diabetes). But since oral glucose tolerance tests are time-consuming and unpleasant, in 1997 the ADA, along with the WHO, created standards for diagnosing both diabetes and a new “sub-diabetes” category, called impaired fasting glucose, defined as a result of 110–125 mg/dl from a fasting blood glucose test (with higher than 125 mg/dl indicating diabetes). Then, in 2003, the ADA lowered its threshold for impaired fasting glucose to 100 mg/dl. And in 2009, the ADA set the criteria for prediabetes — its first use of the term as an official diagnosis — as an HbA1c[9] level of 6.0% to 6.5% (with higher than 6.5% indicating diabetes). The next year, the ADA lowered the threshold for prediabetes to an HbA1c level of 5.7%.

The authors of the BMJ article warn that having the diagnostic category of prediabetes invites pharmaceutical companies, and by extension doctors, to treat the condition using drugs — even though a focus on diet and exercise is more important. Furthermore, with so many people falling under the prediabetes umbrella — and with a relatively weak relationship between having prediabetes and developing diabetes within ten years — the authors conclude that the term is simply not useful, and that efforts to improve diet and exercise habits should be focused on the entire population. This change in focus, they suggest, would reduce diabetes rates more effectively than singling out 35% or 37% of the population.

What do you think — is the term “prediabetes” useless, if all you’re supposed to do is improve your diet and exercise, or is it a useful motivator to make lifestyle changes? If you have Type 2 diabetes, were you previously diagnosed with prediabetes (or another variant of “sub-diabetes”)? Do you think this diagnosis had — or would have had — any effect on you, positive or negative? Should an increase in the rate of prediabetes be seen as alarming, even if diabetes rates aren’t rising as fast? Leave a comment below!

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