BMC Public Health 2007, 7:277 http://www.biomedcentral.com/1471-2458/7/277 kg/m2 (OR = 4.04; p < 0.0001), or had been diagnosed with dyslipidemia (OR = 3.95; p < 0.0001), hypertension (OR = 4.82; p < 0.0001), or with cardiovascular disease (OR = 3.38; p < 0.0001). Conclusion: The SHIELD design allowed for a very large, community-based sample with broad demographic representation of the population of interest. When comparing results from the SHIELD screening survey (self-report only) to those from NHANES 1999–2002 (self-report, clinical and laboratory evaluations), the prevalence of diabetes was similar. SHIELD allows the identification of respondents with and without a current diagnosis of the illness of interest, and potential longitudinal evaluation of risk factors for future diagnosis of that illness. Background Studies have shown that the prevalence of diagnosed dia- betes mellitus (DM) in the US is increasing. Mokdad et al.[1], using data from the Behavioral Risk Factor Surveil- lance System (BRFSS), a cross-sectional telephone survey conducted by the Centers for Disease Control and Preven- tion and state health departments, showed that the preva- lence of self-reported diagnosis of DM increased from 4.9% in 1990 to 6.5% in 1998 to 7.3% in 2000 [1,2]. Using data from four consecutive National Health and Nutrition Examination Surveys, Kanjilal et al. [3] showed a similar, significant increase in prevalence of self- reported diagnosis of DM, as well as a significant increase in total (diagnosed and undiagnosed) prevalence of DM. Further, they showed that DM prevalence increased most among persons with lower income and education levels [3]. The purpose of this study was to estimate the prevalence in 2004 of self-reported diagnosis of DM and prevalence of specific risk factors associated with diabetes in a com- munity-based population. Additionally, individuals with risk factors for diabetes were identified to determine sim- ilarities and differences with diabetes patients. SHIELD (Study to Help Improve Earlyevaluation and manage- ment of risk factors Leading to Diabetes), the largest sur- vey of its kind, began with an initial cross-sectional snapshot of the US population, followed by longitudinal questionnaires designed to evaluate parameters poten- tially related to DM, and is the first prospective study to examine select risk factors (RFs) for future diagnoses of DM. This study was also designed to provide insight into health-related knowledge, behaviors, and attitudes as well as their implications for individuals' transitions to a DM diagnosis and progression of DM treatments. The SHIELD design and methodology are described herein, along with the initial, cross-sectional results of parameters related to DM compared with findings from the National Health and Nutrition Examination Survey (NHANES) 1999– 2002 data. Methods SHIELD consists of three phases: 1) an initial screening, cross-sectional survey that used a general population screening questionnaire to identify cases of interest; 2) the baseline survey, in which the identified respondents were followed up longitudinally with a longer, more detailed questionnaire assessing each individual's health status, health knowledge and attitudes, and current behaviors and treatments; and 3) annual follow-up questionnaires to assess disease progression, which encompassed a) tran- sition from at risk status to diagnosed DM, b) progression of treatment over the course of the disease, and c) the associated clinical and economic burden. Results from the first two phases are presented here. Respondents volun- teered to complete the surveys without compensation. Screening questionnaire The initial screening questionnaire was mailed in April 2004 to a stratified random sample of 200,000 house- holds in the US. These households were a part of the Tay- lor Nelson Sofres National Family Opinion, Inc. (TNS NFO) survey panel, which is a market research firm that maintains a panel of households throughout the US for marketing and research purposes. The panel was con- structed to be representative of the US population in terms of residence (including both geographic region and household area population size), age of the head of household and household income and size. The require- ments for participation included being 18 years of age and having a telephone and mailing address. Random sam- ples of households were invited to enroll in the panel, and demographic information was obtained from those who enroll (and updated every 2 years). Households who agreed to participate were invited to take part in periodic surveys. The NFO panel has been used previously to deter- mine general population prevalence of migraine [4,5], bipolar disorder [6], disease related impairment [7-9], and depression and comorbidity in epilepsy and asthma [10]. The SHIELD screening survey used 12 questions created by an expert advisory panel to identify individuals with DM (and type of DM) or RFs associated with a diagnosis of DM. After being mailed, the screening questionnaire was completed by the head of the household who answered for up to four adult members of the household (≥18 years of age). The head of household was identified Page 2 of 9 (page number not for citation purposes)