Screening for Prediabetes and Diabetes

A new report advises screening all “overweight or obese” adults between 40 and 70 for diabetes and prediabetes. The American Diabetes Association (ADA) thinks that guideline leaves too many people out. Are we screening too much or too little?

The recommendations from the U.S. Preventive Services Task Force (USPSTF) were published in the Annals of Internal Medicine. USPSTF called for the use of “intensive behavioral counseling” for people with prediabetes. Prediabetes means having higher than normal blood glucose, but not quite in the diabetic range.

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About 86 million Americans are thought to have prediabetes. About 8 million Americans are thought to have undiagnosed diabetes. Most of the people identified by screening, then, would have prediabetes, not full-blown diabetes. Both conditions put patients at risk for cardiovascular disease, eye and kidney damage, and other problems, but the risk in prediabetes is far lower.

ADA issued a press release saying they were “tremendously disappointed” with the recommendations. ADA liked that more people will be screened than under the old (2008) recommendations. Those called only for screening adults with high blood pressure. But earlier drafts of the new recs had called for screening any heavy adults with diabetes risk factors. That part was dropped from the final version.

Risk factors included a high percentage of abdominal fat, physical inactivity, family history of diabetes, smoking, high blood pressure, and membership in pretty much any ethnic group except Europeans. ADA is unhappy that many of those people will not be screened under the new recs. Robert Ratner, MD, ADA Chief Scientific & Medical Officer, called for screening adults of any age who had one of these risk factors.

“Screening” means testing people for a disease when they have no symptoms. The idea is to diagnose people early, before diabetes progresses and complications set in. Screening differs from diagnostic testing, which a doctor should do when a person has symptoms. Diabetes symptoms could include fatigue, blurry vision, pain in legs and feet, certain skin rashes, digestive problems, sexual dysfunction, excessive thirst, and frequent urination, among others.

Nobody argues against testing people who have any of these symptoms. But should everyone be tested because they look a certain way or reach a certain age? What is the benefit of that?

Screening tests
Testing for prediabetes or diabetes can be done in three ways. A fasting blood sugar (FBS) is easy and the cheapest way. An oral glucose tolerance test (OGTT) is more expensive and time-consuming but will find more cases of prediabetes. You have to fast, then drink a high-glucose liquid and have your blood sugar checked at regular intervals for the next few hours.

Screening can also be done with a hemoglobin A1c, or HbA1c, test. This has the advantage that you don’t need to fast for it. For most people, any of these tests will work, but they should be confirmed with a second test unless diabetes symptoms are already present.

After screening
Some believe we have too much screening already. Critics suggest the point of screening is mainly to get more people on more drugs, though the new recommendations do not specifically call for starting people with prediabetes on drugs.

USPSTF and ADA both recommend lifestyle intervention, meaning counseling on diet and exercise with frequent follow-up and support. USPSTF found a number of studies showing that people who received lifestyle interventions had fewer heart attacks and strokes. They were less likely to progress from prediabetes to Type 2 diabetes.

They acknowledged that providing such intensive support was beyond the capacity of most health-care providers. They suggested that patients could be referred for community-based programs to receive “lifestyle intervention.”

USPSTF found that the harms of screening are low, “short-term anxiety but not long-term psychological harms.” They found “the harms of lifestyle intervention…are small to none.” On the other hand, the harms of drug therapy for the prevention of diabetes are “small to moderate, depending on the drug and dosage used.”

Dr. Michael P. Pignone, MD, MPH, FACP, one of the authors of the recommendation, said, “Part of the task force’s intent is to get physicians to think about lifestyle intervention more, and it’s also a call to make effective lifestyle programs more available.”

This sounds good. I’m suspicious though. We all know you can tell people to change their eating and exercise until you bore them to death, but long-term change remains very difficult. That’s because our environments push us to eat and act the way we do. Stress drives us to eat widely available high-sugar foods; difficult lives interfere with exercise. To make a difference in prediabetes and in Type 2, we will need social changes, people working together to create a healthier, less stressful environment.

I’m also not sure how being told you have prediabetes helps you. I guess it’s supposed to be a wake-up call, and it might be for some people. For others, it will be another thing to worry about, another reverse placebo, confirming that they are not well and have little hope.

Most of our readers are past the point of screening. But if you have family members or friends who might be thinking about getting screened, this recommendation supports having the test. Under the Affordable Care Act, the test should be free if you’re over 40. Whatever the results, let them know they can handle it, as you are doing.

  • JohnC

    The fasting glucose test isn’t great for discovering many blood sugar problems – you have all night for levels to return to near normal. Hence you could have a problem and it could take several years before it was discovered. An A1c gives an average but can still miss some undesirable swings in blood sugar.
    On doctor appointments where you don’t have to fast you should be asked to eat a fairly high carb meal about an hour or so before. A simple strip test will quickly show if you have a problem. Simple and inexpensive! Should be part of most appointments like a blood pressure test . And just because you don’t fit the weight profile doesn’t mean this test should be skipped.