Advanced glycation end products (AGEs) are bioactive molecules found in foods and generated endogenously in the body. AGEs induce cross-linking of collagen and increase the stiffness of skeletal muscle and cartilage. We characterized the relationship between a plasma AGE, carboxymethyl-lysine (CML), and slow walking speed (lowest quintile of walking speed) in older adults. Walking speed over a 4 m course was assessed in 944 adults, aged >or=65 years, in the InCHIANTI study, a population-based study of aging and mobility disability conducted in two towns in Tuscany, Italy. Participants in the highest quartile of plasma CML were at higher risk of slow walking speed (Odds Ratio [O.R.] 1.56, 95% Confidence Interval [C.I.] 1.02-2.38, P = 0.04) compared to those in the lower three quartiles of plasma CML in a logistic regression models adjusting for age, education, cognitive function, smoking, and chronic diseases. After exclusion of participants with diabetes, participants in the highest quartile of plasma CML were at higher risk of slow walking speed (O.R. 1.87, 95% C.I. 1.15-3.04, P = 0.01) adjusting for the same covariates. In older community-dwelling adults, elevated plasma CML is independently associated with slow walking speed.