Diabetes Prevention: More Than Just Screening and Lifestyle Changes

Hi, everyone. I'm Dr Kenny Lin. I am a family physician at Georgetown University Medical Center and I blog at Common Sense Family Doctor.

In March 2016, the Centers for Medicare & Medicaid Services (CMS) proposed a national expansion of the Diabetes Prevention Program^[1] (DPP), an intensive lifestyle change intervention modeled after a successful 2002 randomized trial^[2] of patients at high risk of developing type 2 diabetes. In the original trial, the lifestyle intervention outperformed both metformin and placebo in reducing the incidence of diabetes over 3 years. The Medicare DPP proposal is discussed in detail in a webinar from the CMS Innovation Center^[3] and was recently highlighted by Health and Human Services Secretary Sylvia Burwell^[4] as a cost-saving preventive health innovation originating from the Affordable Care Act.

To identify high-risk patients, the Centers for Disease Control and Prevention and the American Medical Association are leading a campaign encouraging adults to be screened for prediabetes, which is estimated to affect 1 in 3 Americans. Last year, the US Preventive Services Task Force (USPSTF) recommended that primary care clinicians screen overweight or obese adults between the ages of 40 and 70 years for abnormal blood glucose levels as part of the cardiovascular risk assessment, and that patients meeting criteria for prediabetes be provided or referred to "intensive behavioral counseling interventions to promote a healthful diet and physical activity."^[5]

However, I have some qualms about screening for prediabetes in the name of diabetes prevention. Although you won't find a more evidence-based guideline panel than the USPSTF, existing evidence does not show that measuring blood glucose levels improves health outcomes, even in high-risk patients. According to the Task Force's own literature review, the largest randomized controlled trial of screening for diabetes^[6] found no mortality benefit after 10 years compared with usual care.

Why wouldn't earlier detection of elevated blood glucose levels lead to longer life spans? The consensus diagnostic criteria for prediabetes and diabetes have both been lowered multiple times over the years despite scant proof that lifestyle change or medications reduce cardiovascular events or deaths in patients diagnosed through screening.

My second concern is that screening for prediabetes will lead to overdiagnosis in primary care practices. If 33 out of every 100 adults have prediabetes and studies suggest that less than half of them will develop diabetes within 10 years, we will be giving 16 or 17 out of every 100 adults a diagnosis that doesn't provide health benefits. Being labeled "prediabetic" could also lead to harm through psychological stress or prescriptions for diabetes medications, a common though unproven treatment strategy for patients with prediabetes who are unable or unwilling to modify their physical activity or dietary patterns.

Finally, there are disadvantages to taking an individual rather than a population health approach to diabetes prevention. Sticking with lifestyle changes requires consistent effort on the part of the patient and clinician, and can be a never-ending struggle at home and in work environments that facilitate overeating and sedentary behavior. Noting that adults with lower socioeconomic status are much more likely than wealthy individuals to suffer from diabetes, researchers from the Mayo Clinic have appropriately criticized the DPP's "prevent diabetes one person at a time" approach as ignoring "the underlying conditions—poverty, income inequality, loneliness, and socioeconomic stress—that are conducive to more obesity and more cases of diabetes."^[7]

Changing unhealthy environments can be a far more effective and long-lasting intervention than one-on-one clinical counseling. In the late 1990s, the US Department of Housing and Urban Development randomly assigned 4500 women with children in high-poverty urban areas to no housing vouchers, unrestricted traditional vouchers, or vouchers that could only be redeemed for housing in low-poverty areas. Ten to 15 years later, the group receiving traditional vouchers was no healthier than the control group, but the group receiving low-poverty vouchers had significantly lower body mass index and glycated hemoglobin levels.^[8]

Although the Medicare DPP as proposed should improve the health of many of our patients, in order to prevent diabetes without worsening health disparities, family physicians also require resources to address social determinants of health. To this end, the American Academy of Family Physicians recently published a position paper^[9] describing strategies for collaborating effectively with public health partners to lead the prevention of chronic diseases in our communities.

This has been Dr Kenny Lin for Medscape Family Medicine. Thank you for listening.

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Cite this: Diabetes Prevention: More Than Just Screening and Lifestyle Changes - Medscape - Oct 18, 2016.