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PORTLAND, OR – To screen or not to screen for diabetes.
That is the question researchers tackled as they worked on an upcoming update of U.S. Preventive Services Task Force recommendations on whether physicians should screen asymptomatic, non-pregnant adults for type 2 diabetes. The results were published recently in Annals of Internal Medicine.
Proponents have argued that widely screening for diabetes could lead to earlier identification as well as earlier and more intensive treatment, which could improve health outcomes. Studies on the issue haven’t completely borne that out, however, finding that screening does not improve mortality rates after 10 years of follow up.
A study team from Pacific Northwest Evidence-based Practice Center and Oregon Health & Science University reviewed studies 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.
Researchers found that, in two trials, screening for diabetes was associated with no 10-year mortality benefit vs. not screening. While 16 trials consistently found that treatment of impaired fasting glucose (IFG) or impaired glucose tolerance ( IGT) was associated with delayed progression to diabetes, most trials of treatment of IFG or IGT found no effects on all-cause or cardiovascular mortality.
One trial indicated that lifestyle modification was associated with decreased risk for both outcomes after 23 years, while another trial found no effect of an intensive multifactorial intervention on risk for all-cause or cardiovascular mortality for screen-detected diabetes vs. standard control.
In diabetes that was not specifically screen-detected, nine 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.
In 2008, the USPSTF recommended that physicians screen for type 2 diabetes in adults with treated or untreated sustained blood pressure greater than 135/80 mm Hg, even if they showed no symptoms of high blood sugar. That recommendation was based both on the ability of screening to identify persons 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.
Later studies suggested otherwise.
“Screening for diabetes did not improve mortality rates after 10 years of follow-up,” the authors point out. “More evidence is needed to determine the effectiveness of treatments for screen-detected diabetes. Treatment of IFG or IGT was associated with delayed progression to diabetes.”
Draft recommendations for public comment were posted last October, and the task force currently is incorporating that commentary to finalize the recommendations for future release.