Methods and Limitations
We estimated the number and percentage of the U.S. population with diagnosed diabetes by using data from the National Health Interview Survey (NHIS) of the National Center for Health Statistics (NCHS), Centers for Disease Control and Prevention (CDC). Conducted continuously since 1957, the NHIS is a health survey of the civilian, noninstitutionalized, household population of the United States. The survey provides information on the health of the United States 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.1,2 The NHIS was redesigned in 1997.3
Each year, a one-sixth subsample of NHIS respondents was asked whether in the past 12 months they or any family member had diabetes. Three-year averages were used to improve the precision of the annual estimates.
The NHIS was redesigned in 1997.3 In the redesigned survey, all sampled adults are asked whether a health professional had ever told them they had diabetes. To exclude gestational diabetes, women were asked whether they had been told they had diabetes other than during pregnancy. Also, parents of sampled children were asked whether their child had diabetes. Three-year averages were used to improve the precision of the annual estimates.
Diabetes prevalence estimates are presented by age, race, ethnicity, and sex. Persons of Hispanic origin may be of any race. The race groups include persons of both Hispanic and non-Hispanic origin. Prevalence estimates were age-adjusted using National Center for Health Statistics estimates of the 2000 U.S. population as the standard. Because the estimates were produced prior to the year 2000, a slight difference may occur between crude and age-adjusted rates for 2000.4 The numbers in the table are rounded and may not sum to totals.
Because the NHIS survey was redesigned, two changes may have affected trends. First, the diabetes question was changed. Second, proxy respondents (i.e., household members responding for absent adult members) who tend to under report disease were no longer used in the survey.
Approximately one-third of persons with diabetes are unaware they have diabetes because their diabetes has not been diagnosed.5 Therefore, the NHIS underestimates the true prevalence of diabetes.
- Massey JT, Moore TF, Parsons VL, Tadros W. Design and estimation for the National Health Interview Survey, 1985–1994. National Center for Health Statistics. Vital Health Stat 1989;2(110).
- Botman SL, Moore TF, Moriarity CL, Parsons VL. Design and estimation for the National Health Interview Survey, 1995–2004. National Center for Health Statistics. Vital Health Stat 2000;2(130).
- Centers for Disease Control and Prevention, National Health Interview Survey (NHIS) Website, see 1997 Survey Description,
- Klein RJ, Schoenborn CA. Age Adjustment Using The 2000 projected U.S. population. Healthy People Statistical Notes, No. 20. Hyattsville, Maryland: National Center for Health Statistics, 2001.
- Centers for Disease Control and Prevention. National Diabetes Fact Sheet: National Estimates and General Information on Diabetes and Prediabetes in the United States. Atlanta, GA: U.S. Department of Health and Human Services, Centers for Disease Control and Prevention; 2011.