Methods and Limitations
We estimated the percentage of American adults aged 18 years and older with diabetes who took insulin or oral medications using data from the National Health Interview Survey (NHIS) of the National Center for Health Statistics (NCHS), Centers for Disease Control and Prevention (CDC). NHIS is a health survey of the civilian, noninstitutionalized, household population of the United States that has been conducted since 1957. The survey provides information on the health of the U.S. population, including information on the prevalence and incidence of disease, the extent of disability, and the use of health care services. The multistage probability design of the survey has been described elsewhere.1
Adult respondents were asked whether a health professional had ever told them they had diabetes. To exclude gestational diabetes, the NHIS asked women participants whether they had been told that they had diabetes other than during pregnancy. Responses to the following questions were used to determine the percentage of adults with diabetes who were taking insulin or oral medication: “Are you now taking insulin?” and “Are you now taking diabetic pills to lower your blood sugar? These pills are sometimes called oral agents or oral hypoglycemic agents.”
Responses to these questions were used to determine the percentage of adults with diabetes who took insulin or oral medications. Adults with diabetes were categorized into five groups of medication use—those taking insulin only, those taking oral medications only, those taking both, those taking either insulin or oral medication, and those taking neither insulin nor oral medications. We considered respondents to be taking “any diabetes medication” if they reported taking either insulin, oral medication, or both. Estimates of the percentage of adults with diabetes taking diabetes medications are presented by age, race, sex, and ethnicity. The racial groups include persons of both Hispanic and non-Hispanic origin. Persons of Hispanic origin may be of any race. Three-year averages were used to improve the precision of an annual estimates. Estimates were age-adjusted on the basis of the 2000 U.S. standard population.
The NHIS data reflect medication uses among people with self-reported diagnosed diabetes only. The proportion of those with undiagnosed diabetes but unaware because their diabetes has not been diagnosed range from about one-fourth2 to about one-third.3 In the NHIS, no questions are asked about the type of diabetes, precluding the assessment of medication and insulin use among people with type 2 diabetes.
- Botman SL, Moore TF, Moriarity CL, Parsons VL. Design and estimation for the National Health Interview Survey, 1995–2004. Vital and Health Statistics. 2000;2(130).
- Centers for Disease Control and Prevention. National Diabetes Fact Sheet: National Estimates and General Information on Diabetes and Prediabetes in the United States. 2011. Atlanta, GA: Centers for Disease Control and Prevention, U.S. Department of Health and Human Services; 2011.
- Cowie CC, Rust KF, Ford ES, et al. Full accounting of diabetes and pre-diabetes in the U.S. population in 1988–1994 and 2005–2006. Diabetes Care. 2009;32(2):287-294.