A systematic evidence review by the U.S. Preventive Services Task Force suggests that screening asymptomatic adults for elevated glucose levels could help delay progression to diabetes but has not been shown to improve mortality rates.
Researchers for the Task Force reviewed randomized, controlled trials; controlled, observational studies; and systematic reviews published from 2007 through October 2014 to assess the benefits and harms of screening for type 2 diabetes, impaired fasting glucose, or impaired glucose tolerance among asymptomatic adults. The review, meant to inform recommendations to be published later, was published online April 14 and in print June 2 by Annals of Internal Medicine.
In 2 trials, screening for diabetes was associated with no 10-year mortality benefit versus no screening (hazard ratio, 1.06; 95% CI, 0.90 to 1.25). Sixteen trials consistently found that treatment of impaired fasting glucose or impaired glucose tolerance was associated with delayed progression to diabetes. Most treatment trials found no effects on all-cause or cardiovascular mortality, although 1 trial found that lifestyle modification was associated with decreased risk for both outcomes after 23 years.
For screening-detected diabetes, 1 trial found no effect of an intensive multifactorial intervention on risk for all-cause or cardiovascular mortality versus standard control. In diabetes that was not specifically screening-detected, 9 systematic reviews found that intensive glucose control did not reduce risk for all-cause or cardiovascular mortality and results for intensive blood pressure control were inconsistent.
The previous Task Force recommendation on this topic, published in 2008, stated that physicians should screen for type 2 diabetes in asymptomatic adults with treated or untreated sustained blood pressure greater than 135/80 mm Hg. This recommendation was based on the ability of screening to identify people with diabetes and evidence that more intensive blood pressure treatment was associated with reduced risk for cardiovascular events, including cardiovascular mortality, in patients with diabetes and hypertension.
An editorial accompanying the current review offered an alternative opinion, suggesting that a national policy to screen all persons at high risk for diabetes (a position closer to the American Diabetes Association policy) would help identify those with undetected diabetes and prediabetes. The editorialist outlines the evidence supporting the benefits of early identification and states that “the risk of associated with screening are small or none” and “detection of prediabetes and diabetes would offer a strategic window of opportunity to intervene on other [cardiovascular disease] risk factors in an integrated manner.” The editorial concludes, “Without screening, 90% of prediabetes cases will remain undetected, and we will continue to miss the opportunity to aggressively implement strategies to prevent diabetes and remain unable to slow the growing costs of managing diabetes and its complications.”