Prevalence of self-reported diagnosis of diabetes mellitus and associated risk factors in a national survey in the US population: SHIELD (Study to Help Improve Early evaluation and management of risk factors Leading to Diabetes).

Background: Studies derived from continuous national surveys have shown that the prevalence of diagnosed diabetes mellitus in the US is increasing. This study estimated the prevalence in 2004 of self-reported diagnosis of diabetes and other conditions in a community-based population, using data from the Study to Help Improve Early evaluation and management of risk factors Leading to Diabetes (SHIELD).

Methods: The initial screening questionnaire was mailed in 2004 to a stratified random sample of 200,000 households in the US, to identify individuals, age > or = 18 years of age, with diabetes or risk factors associated with diabetes. Follow-up disease impact questionnaires were then mailed to a representative, stratified random sample of individuals (n = 22,001) in each subgroup of interest (those with diabetes or different numbers of risk factors for diabetes). Estimated national prevalence of diabetes and other conditions was calculated, and compared to prevalence estimates from the National Health and Nutrition Examination Survey (NHANES) 1999-2002.

Results: Response rates were 63.7% for the screening, and 71.8% for the follow-up baseline survey. The SHIELD screening survey found overall prevalence of self-reported diagnosis of diabetes (either type 1 or type 2) was 8.2%, with increased prevalence with increasing age and decreasing income. In logistic regression modeling, individuals were more likely to be diagnosed with type 2 diabetes if they had abdominal obesity (odds ratio [OR] = 3.50; p < 0.0001), BMI > or =28 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.