Noninsulin-dependent diabetes mellitus (NIDDM) is associated with decrements in several cognitive functions. Among the variables that apparently contribute to the decline in cognitive performance is poor glucose control, as measured by hemoglobin A1c. Elevated levels of triglycerides in diabetics may also contribute to this cognitive decline through the increased incidence of atherosclerosis in these patients. The authors examined the relationship between triglycerides and cognitive performance in 246 NIDDM outpatients, aged 55-74 years. The relationship between triglyceride levels and performance on three cognitive tasks and on a test of reaction time was measured. Elevated levels of triglycerides were associated with significant decrements in performance on the digit symbol substitution test, digit span (backward) test, and on a reaction time measure. High levels of triglycerides, independent of chronic glucose control, appear to contribute to the decreased ability to perform short-term memory tasks in NIDDM.