Screening for Type 2 Diabetes Mellitus: A Systematic Review for the US 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 MEDUNE (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% Cl, 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.