Universal screening for type 2 diabetes may be reasonable for patients age 35 and older

Opportunistic universal screening for type 2 diabetes may increase detection of undiagnosed prediabetes or diabetes at a low cost versus targeted screening, a new study indicates.

Researchers used data from the National Health and Nutrition Examination Survey, 2007-2008 and 2009-2010, to compare opportunistic universal screening with targeted screening as recommended by the U.S. Preventive Services Task Force (USPSTF) and the American Diabetes Association (ADA). Opportunistic universal screening was defined as “screening during a healthcare visit for another purpose, as opposed to adding an additional medical visit purely for the purposes of screening.” The authors estimated the proportion of the U.S. population that would be eligible for diabetes screening according to USPSTF and ADA guidelines and how many patients without diabetes would have to be tested to detect 1 positive test result (number needed to screen, or NNS). The authors defined a positive test result for diabetes by the ADA guidelines, which call for at least 1 of the following: fasting blood glucose level of 126 mg/dL (7.0 mmol/L) or greater, a 2-hour oral glucose tolerance test of 200 mg/dL (11.1 mmol/L) or greater, or an HbA1c level of 6.5% or greater.

The overall study sample involved 10,703 nonpregnant, diabetes-free individuals from NHANES who were considered eligible for diabetes screening. Those who met the ADA guidelines for screening were overweight or obese and had 1 or more additional risk factor for diabetes (e.g., low HDL cholesterol, high triglycerides, and physical inactivity), or were 45 years of age or older regardless of other risk factors. Those who met the USPSTF guidelines for screening were asymptomatic and had a sustained blood pressure of 135/80 mm Hg or greater. Universal screening was assessed by age category: 18 to 34 years, 35 to 44 years, and 45 years or older. The NNS was calculated based on the rate of positive test results. Costs were estimated by using the 2010 Medicare fee schedule. The study results were published online Aug. 14 by the American Journal of Preventive Medicine.

Among the 10,703 NHANES respondents, 81.6% met ADA criteria for screening and 28.2% met USPSTF criteria. The NNS for universal screening decreased at age 35, from 80 among 30- to 34-year-olds to 31 among 35- to 39-year-olds. The authors estimated that for opportunistic universal screening in patients age 35 and older, the NNS would be 15 and the cost would be $66 per positive test result, compared with $62 for the ADA screening strategy and $57 for the USPSTF screening strategy. The study found that 71% of people age 35 to 44 were overweight or obese and that 100% of them had an additional diabetes risk factor; applying the ADA guidelines for screening in this group would have missed 14.6% of positive tests, the authors estimated. Meanwhile, 34% of people 35 years of age and older met USPSTF criteria for screening, and the authors estimated that strict enforcement of the USPSTF guidelines in this group would have meant missing 60.7% of potential positive tests.

The authors noted that they relied on self-report to determine which patients were free of diabetes, that they did not evaluate repeated testing and rescreening, and that a single positive screening test result is not considered a definitive diabetes diagnosis. However, they concluded that using a more universal screening approach for diabetes in patients age 35 and older is easier and can help reduce the prevalence of undiagnosed diabetes in the United States. “Given the substantial benefit of early detection with small incremental costs for extending diabetes screening, and evidence that nearly universal screening is already practiced, it may be time to harmonize guidelines and recognize universal screening for diabetes in adults aged ≥35 years as formal policy,” the authors wrote.