Screening for Type 2 Diabetes Mellitus: A Systematic Review for the U.S. Preventive Services Task Force

BACKGROUND: Screening for type 2 diabetes mellitus could lead to earlier identification and treatment of asymptomatic diabetes, impaired fasting glucose (IFG), or impaired glucose tolerance (IGT), potentially resulting in improved outcomes. PURPOSE: To update the 2008 U.S. Preventive Services Task Force review on diabetes screening in adults. DATA SOURCES: Cochrane databases and MEDLINE (2007 through October 2014) and relevant studies from previous Task Force reviews. STUDY SELECTION: Randomized, controlled trials; controlled, observational studies; and systematic reviews. DATA EXTRACTION: Data were abstracted by 1 investigator and checked by a second; 2 investigators independently assessed study quality. DATA SYNTHESIS: 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 IFG or 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, although lifestyle modification was associated with decreased risk for both outcomes after 23 years in 1 trial. For screen-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 screen-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. LIMITATION: The review was restricted to English-language articles, and few studies were conducted in screen-detected populations. CONCLUSION: Screening for diabetes did not improve mortality rates after 10 years of follow-up. 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. PRIMARY FUNDING SOURCE: Agency for Healthcare Research and Quality.