1. From a systematic review, the USPSTF found inadequate evidence to support any 10-year mortality benefit associated with screening for diabetes.
2. Treatment of impaired glucose tolerance (IGT) and impaired fasting glucose (IFG) was associated with delayed progression to diabetes.
Evidence Rating Level: 2 (Good)
Study Rundown: Risk factors for type 2 diabetes have been used to create screening guidelines, but the value of such screening in asymptomatic patients is unclear. In its 2008 recommendation, the United States Preventive Services Task Force (USPSTF) found insufficient evidence to weigh the benefit or harm of screening for type 2 diabetes in asymptomatic adults, but did recommend screening for those with high blood pressure. From this updated systematic review, two RCTs directly comparing screening status did not show a benefit to mortality outcomes at 10 years of follow up. In a low-quality study from China, treatment of screen-detected diabetes, IFG, IGT, or early diabetes did show a morality benefit at 23 years. Additionally, some studies demonstrated that lifestyle and pharmacologic interventions may be effective in delaying or preventing progression to diabetes in patients with risk factors, although the impact of interventions to lower glucose and blood pressure were inconsistent. Limitations to this review included the use of international studies, studies that used patients not identified by screening, and heterogeneity in quality of studies. Overall, more evidence is necessary to assess the role of diabetes screening, as well as the clinical value of early intervention.
In-Depth [systematic review]: From the ADDITION and Ely trials, no mortality benefit was found with screening compared to not screening for diabetes (HR 1.06, 95%CI 0.90-1.25; adjusted HR 0.79, 95%CI 0.63-1.00 for all-cause mortality). The RCT from Da Qing, China showed a reduced risk of all-cause morality (HR 0.71, 95%CI 0.51-0.99) and cardiovascular mortality (HR 0.59; 95%CI 0.36-0.96) among overweight persons with IGT. Intensive glucose-lowering therapy was associated with reduced risk of non-fatal MI in 6 reviews (RR 0.83-0.87). Similarly, intensive BP lowering was associated with reduced risk of all-cause mortality (RR 0.90, 95%CI 0.82-0.98) in 1 review. However, for glucose- and BP-lowering therapies, individual results and study definitions were inconsistent. Lifestyle interventions were associated with decreased risk for disease progression (pooled RR 0.55, 95%CI 0.43-0.70). Multifactorial therapy/intervention showed a trend for benefit, but it was not statistically significant (RR 0.89, 95%CI 0.78-1.02).
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