NHANES is an ongoing, cross-sectional survey of representative samples of the U.S. civilian noninstitutionalized population. The survey uses a complex multistage probability design. Data are collected through in-person interviews and medical examinations. During 1999-2002, NHANES participants were asked, “Other than during pregnancy, have you ever been told by a doctor or health professional that you have diabetes or sugar diabetes?” Participants who answered “yes” to this question were classified as having diagnosed diabetes; if the answer was “no” or “borderline,” participants were classified as not having diagnosed diabetes. LED was defined as the presence of either PAD (ankle/brachial blood pressure ratio <0.9), PN (one or more insensate areas, on the basis of monofilament testing of foot sensation), self-report of foot/leg ulcers, or technician-observed toe or foot lesion or amputation. Further details of these measures have been described previously.5 Mobility limitation was determined on the basis of participants' response to the questions, “How much difficulty do you have walking for a quarter of a mile; walking up 10 steps without resting; and walking from one room to another on the same level?” Participants who responded “some difficulty,” “much difficulty,” or “unable to do” to one or more of the three questions were classified as having mobility limitation; participants who responded “no difficulty” to all three questions were classified as having no mobility limitation. Prevalence of mobility limitation was calculated for adults with and without diagnosed diabetes and LED by age and sex for participants aged ≥40 years who had complete data in the interview and examination variables of interest (n = 4,689); of the 6,059 persons aged ≥40 years who received the health examination, 1,370 (23%) were excluded from the analysis because of missing data. All reported percentages and 95% confidence intervals (CIs) were estimated using examination weights and taking into account the complex sampling design. Data were age-adjusted to the 2000 U.S. standard population using the age groups 40-59 years, 60-74 years, and ≥75 years. Logistic regression analysis was used to assess the association of diabetes status and LED status with mobility limitation, including whether an interaction existed between diabetes status and LED status in their associations with mobility limitation, after adjusting for demographic characteristics.