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About 21 million people in the U.S. were diagnosed with diabetes in 2010, and an estimated 8 million people went undiagnosed. A new U.S. Preventive Services Task Force (USPSTF) review of existing literature assessed the benefits and harms of screening people who do not have symptoms of type 2 diabetes, impaired fasting glucose (IFG), or impaired glucose tolerance (IGT). Published in the Annals of Internal Medicine, it found that screening for type 2 diabetes did not affect mortality but that treatment of IFG and IGT delayed progression to diabetes.

The panel looked at studies published from 2007 to October 2014. They found that screening helped delay the onset of type 2 diabetes because it identified those who could benefit from treatment of IGT or IFG; however, they did not find improved mortality rates in this group at the 10-year mark of follow-up.

Specifically, in two of the trials evaluated by USPSTF, screening for type 2 diabetes was associated with no 10-year mortality benefit, compared with no screening. Sixteen trials the team evaluated consistently found that treatment of IFG or IGT was associated with delayed progression to type 2 diabetes. However, most trials found that treating IFG or IGT had no effects on all-cause or cardiovascular mortality, while lifestyle modification was associated with decreased risk for those outcomes after 23 years in one of the trials. For diabetes diagnosed through screening, one trial found that an intensive multifactorial intervention had no effect on cardiovascular mortality, compared with a control group. Finally, in diabetes not diagnosed through screening, nine systemic reviews determined that intensive glucose control did not reduce cardiovascular or all-cause mortality risk, and the results tied to intensive blood pressure control were inconsistent.

USPSTF recommended in 2008 that clinicians screen for type 2 diabetes in asymptomatic adults who had a treated, sustained blood pressure reading greater than 135/80 Hg. “Since then, evidence shows that an intensive multifactorial intervention for screen-detected diabetes aimed at decreasing glucose and lipid levels and blood pressure was not associated with a reduction in risk for all-cause or cardiovascular mortality or morbidity compared with standard treatment,” leading to the updated analysis, according to a press release.