Background: Carotid-femoral pulse wave velocity (cfPWV) is a reference measure of central (elastic) artery stiffness and a risk factor for cardiovascular disease. Femoral-ankle pulse wave velocity (faPWV) is a measure of peripheral (musculo-elastic) arterial stiffness. The ratio of fasting triglycerides (TG) to high-density lipoprotein cholesterol (HDL-C) is a novel and practical marker of insulin resistance (IR), a dysregulation that often precedes diabetes. While diabetes is a known risk factor for arterial stiffening, associations of IR with segment-specific measures of PWV, in those without diabetes, have not been well characterized.
Objective: To characterize the cross-sectional association of IR, as indexed by TG/HDL-C, with central and peripheral arterial stiffness by race and gender in older adults without diagnosed diabetes. We hypothesized that TG/HDL-C is positively associated with cfPWV and inversely associated with faPWV.
Methods: Our study population included 2477 white and 564 African American adults without diagnosed diabetes examined in 2011-2013 by the ARIC study. cfPWV (cm/s) and faPWV (cm/s) were measured using the Omron VP-1000 Plus system. TG (mg/dL)/HDL-C (mg/dL) was evaluated continuously and categorically. For TG/HDL-C categories, race and gender specific receiver operator characteristic curves were used to determine cut points corresponding to the 75th percentile of fasting insulin, optimized using the Youden index. Elevated TG/HDL-C was dichotomously defined by cut points. Multivariable linear regression was used to model associations, adjusted for age, heart rate, gender, current smoking, and race-center; analyses were stratified by race and gender.
Results: The study population was 19% African American and 62% women; mean age was 75 years (SD: 5). TG/HDL-C was positively and monotonically associated with cfPWV, and inversely associated with faPWV. Overall, compared to those without elevated TG/HDL, those with elevated TG/HDL-C had higher cfPWV (β=56 cm/s, 95% CI 35, 78) and, although not significant, lower faPWV (β=-9 cm/s, 95% CI -22, 5). cfPWV was higher in those with elevated TG/HDL-C: 59 cm/s (95% CI 32, 87) in white women, 40 cm/s (95% CI 3, 78) in white men, 50 cm/s (95% CI -20, 120) in African American women, and 101 cm/s (95% CI -10, 212) in African American men. faPWV was lower in white women (β=-23 cm/s, 95% CI -42, -4), but not statistically different in other subgroups. The association of elevated TG/HDL-C with cfPWV and faPWV did not differ by race or gender (p-values >0.1 for all tests for interaction).
Conclusions: Higher levels of IR, as indexed by TG/HDL-C, were associated with higher central arterial stiffness and lower peripheral arterial stiffness. These results suggest a role of IR in arterial stiffening in older adults without diabetes.