OBJECTIVE -Since 1997, the American Diabetes Association has recommended that nondiabetic individuals Ն45 years of age be screened for diabetes at least every 3 years. We sought to characterize the frequency, methods, and results of diabetes screening in routine clinical practice.RESEARCH DESIGN AND METHODS -We studied opportunistic screening in nondiabetic members of a health maintenance organization Ն45 years of age who were assigned to a large, integrated, academic health care delivery system. Screening was defined as the first glucose, HbA 1c , or oral glucose tolerance test (OGTT) performed between 1 January 1998 and 31 December 2000. Chart review was performed to determine the prevalence of diabetes risk factors and to describe follow-up.RESULTS -Of 8,286 nondiabetic patients Ն45 years of age, 69% (n ϭ 5,752) were screened. The frequency of screening was greater in patients with one or more primary care visits and increased with age. Women were more likely to be screened than men, and patients with at least one diabetes risk factor were more likely to be screened than those without risk factors. Random plasma glucose was the most common screening test (95%). Four percent (n ϭ 202) of those screened had abnormal results. Only 38% (n ϭ 77) of those with abnormal results received appropriate follow-up, and 17% (n ϭ 35) were diagnosed with diabetes within 6 months of screening. The yield of screening was very low (0.6%, 35 of 5,752).CONCLUSIONS -Despite frequent screening and appropriate targeting of high-risk patients, follow-up of patients with abnormal results is uncommon and the yield of screening is low. Interventions are needed to help physicians recognize and provide appropriate follow-up for patients with potentially abnormal random glucose levels. Diabetes Care 27:9 -12, 2004I n 2001, 16.7 million Americans were diagnosed with diabetes (1). Unfortunately, ϳ5.4 million Americans with diabetes remained undiagnosed (2). In 1997, the American Diabetes Association (ADA) Expert Committee on the Diagnosis and Classification of Diabetes Mellitus recommended that all nondiabetic individuals Ն45 years of age be screened for diabetes at 3-year intervals as a part of their routine medical care (opportunistic screening). The ADA recommended that screening be performed with either fasting plasma glucose levels or oral glucose tolerance tests (OGTTs) (3). Currently, under the direction of Secretary of Health and Human Services Tommy Thompson, a consortium of federal agencies is exploring the feasibility of a major new "detection initiative" to find the 5.4 million Americans with undiagnosed diabetes.Support for diabetes screening is not based on randomized, controlled clinical trials but on observational data. Analyses of mass screening programs in the former East Germany found that people diagnosed with diabetes as a result of screening had better outcomes than those presenting spontaneously with diabetes (4). More recently, support for screening has come from the U.K. Prospective Diabetes Study, which demonstrated...