Nancy A. Melville
August 24, 2021
The United States Preventive Services Task Force has updated its recommendation on the age of screening for prediabetes and type 2 diabetes in the primary care setting — lowering the age from 40 to 35 years for asymptomatic patients with overweight or obesity and encouraging greater interventions when patients do show a risk.
"The USPSTF concludes with moderate certainty that screening for prediabetes and type 2 diabetes and offering or referring patients with prediabetes to effective preventive interventions has a moderate net benefit," the task force concludes in its recommendation, published Aug. 24 in JAMA.
"Clinicians should offer or refer patients with prediabetes to effective preventive interventions," they write.
Experts commenting on the issue strongly emphasize that it's not just the screening, but the subsequent intervention that is needed to make a difference.
"If young adults newly identified with abnormal glucose metabolism do not receive the needed intensive behavioral change support, screening may provide no benefit," write Richard W. Grant, MD, MPH, and colleagues in an editorial published with the recommendation.
"Given the role of our obesogenic and physically inactive society in the shift toward earlier onset of diabetes, efforts to increase screening and recognition of abnormal glucose metabolism must be coupled with robust public health measures to address the underlying contributors."
BMI Cutoff Lower for At-Risk Ethnic Populations
The recommendation, which updates the task force's 2015 guideline, carries a "B" classification, meaning the USPSTF has high certainty that the net benefit is moderate. It now specifies screening from age 35to 70 for persons classified as overweight (body mass index at least 25) or obese (BMI at least 30) and recommends referral to preventive interventions when patients are found to have prediabetes.
In addition to recommendations of lifestyle changes, such as diet and physical activity, the task force also endorses the diabetes drug metformin as a beneficial intervention in the prevention or delay of diabetes, while noting fewer overall health benefits from metformin than from the lifestyle changes.
A lower BMI cutoff of at least 23 is recommended for diabetes screening of Asian Americans, and, importantly, screening for prediabetes and diabetes should be considered at an even earlier age if the patient is from a population with a disproportionately high prevalence of diabetes, including American Indian/Alaska Native, Black, Hawaiian/Pacific Islander, Hispanic/Latino, the task force recommends.
Screening tests should include fasting plasma glucose, hemoglobin A1c, or an oral glucose tolerance test. Although screening every 3 years "may be a reasonable approach for adults with normal blood glucose levels," the task force adds that "the optimal screening interval for adults with an initial normal glucose test result is uncertain."
Data Review: Few With Prediabetes Know They Have It
The need for the update was prompted by troubling data showing increasing diabetes rates despite early signs that can and should be identified and acted upon in the primary care setting to prevent disease progression.
Data from the Centers for Disease Control and Prevention, for instance, show that while 13% of all U.S. adults 18 years or older have diabetes and 35% meet criteria for prediabetes, as many as 21% of those with diabetes were not aware of or did not report having the disease. Furthermore, only a small fraction — 15% of those with prediabetes — said they had been told by a health professional that they had this condition, the task force notes.
The task force's final recommendation was based on a systematic review of evidence regarding the screening of asymptomatic, nonpregnant adults and the harms and benefits of interventions, such as physical activity, behavioral counseling, or pharmacotherapy.
Among key evidence supporting the lower age was a 2014 study showing that the number of people necessary to obtain one positive test for diabetes with screening sharply drops from 80 among those aged 30-34 years to just 31 among those aged 36-39.
Opportunistic universal screening of eligible people aged 35 and older would yield a ratio of 1 out of just 15 to spot a positive test, the authors of that study reported.
In addition, a large cohort study in more than 77,000 people with prediabetes strongly links the risk of developing diabetes with increases in A1c level and with increasing BMI.
ADA Recommendations Differ
The new recommendations differ from American Diabetes Association guidelines, which call for diabetes screening at all ages for people who are overweight or obese and who have one or more risk factors, such as physical inactivity or a first-degree relative with diabetes. If results are normal, repeat screening at least every 3 years is recommended.
The ADA further recommends universal screening for all adults 45 years and older, regardless of their risk factors.
For the screening of adults over 45, the ADA recommends using a fasting plasma glucose level, 2-hour plasma glucose level during a 75-g oral glucose tolerance test, or A1c level, regardless of risk factors.
The American Association of Clinical Endocrinology also recommends universal screening for prediabetes and diabetes for all adults 45 years or older, regardless of risk factors, and also advises screening those who have risk factors for diabetes regardless of age.
Screening of Little Benefit Without Behavior Change Support
In an interview, Grant added that broad efforts are essential as those at the practice level have clearly not succeeded.
"The medical model of individual counseling and referral has not really been effective, and so we really need to think in terms of large-scale public health action," said Grant, of the division of research, Kaiser Permanente Northern California, Oakland.
His editorial details the sweeping, multifactorial efforts that are needed.
"To turn this recommendation into action — that is, to translate screening activities into improved clinical outcomes — change is needed at the patient-clinician level (recognizing and encouraging eligible individuals to be screened), health care system level (reducing screening barriers and ensuring access to robust lifestyle programs), and societal level (applying effective public health interventions to reduce obesity and increase exercise)," they write.
A top priority has to be a focus on individuals of diverse backgrounds and issues such as access to healthy programs in minority communities, Grant noted.
"Newly diagnosed adults are more likely to be African-American and Latinx," he said.
"We really need to invest in healthier communities for low-income, non-White communities to reverse the persistent health care disparities in these communities."
While the challenges may appear daunting, history shows they are not necessarily insurmountable — as evidenced in the campaign to discourage tobacco smoking.
"National smoking cessation efforts are one example of a mostly successful public health campaign that has made a difference in health behaviors," Grant noted.
The recommendation is also posted on the USPSTF web site.
Grant reports receiving grants from the National Institutes of Health and the Patient-Centered Outcomes Research Institute.