Abstract
BackgroundPrior studies have shown insulin resistance is associated with reduced cardiac autonomic function measured at rest, but few studies have determined whether insulin resistance is associated with reduced cardiac autonomic function measured during daily activities.MethodsWe examined older adults without diabetes with 48-h ambulatory electrocardiography (n = 759) in an ancillary study of the Atherosclerosis Risk in Communities Study. Insulin resistance, the exposure, was defined by quartiles for three indexes: 1) the homeostatic model assessment of insulin resistance (HOMA-IR), 2) the triglyceride and glucose index (TyG), and 3) the triglyceride to high-density lipoprotein cholesterol ratio (TG/HDL-C). Low heart rate variability, the outcome, was defined by <25th percentile for four measures: 1) standard deviation of normal-to-normal R-R intervals (SDNN), a measure of total variability; 2) root mean square of successive differences in normal-to-normal R-R intervals (RMSSD), a measure of vagal activity; 3) low frequency spectral component (LF), a measure of sympathetic and vagal activity; and 4) high frequency spectral component (HF), a measure of vagal activity. Logistic regression was used to estimate odds ratios (OR) and 95% confidence intervals weighted for sampling/non-response, adjusted for age at ancillary visit, sex, and race/study-site. Insulin resistance quartiles 4, 3, and 2 were compared to quartile 1; high indexes refer to quartile 4 versus quartile 1.ResultsThe average age was 78 years, 66% (n = 497) were women, and 58% (n = 438) were African American. Estimates of association were not robust at all levels of HOMA-IR, TyG, and TG/HDL-C, but suggest that high indexes were associated consistently with indicators of vagal activity. High HOMA-IR, high TyG, and high TG/HDL-C were consistently associated with low RMSSD (OR: 1.68 (1.00, 2.81), OR: 2.03 (1.21, 3.39), and OR: 1.73 (1.01, 2.91), respectively). High HOMA-IR, high TyG, and high TG/HDL-C were consistently associated with low HF (OR: 1.90 (1.14, 3.18), OR: 1.98 (1.21, 3.25), and OR: 1.76 (1.07, 2.90), respectively).ConclusionsIn older adults without diabetes, insulin resistance was associated with reduced cardiac autonomic function – specifically and consistently for indicators of vagal activity – measured during daily activities. Primary prevention of insulin resistance may reduce the related risk of cardiac autonomic dysfunction.
Highlights
Prior studies have shown insulin resistance is associated with reduced cardiac autonomic function measured at rest, but few studies have determined whether insulin resistance is associated with reduced cardiac autonomic function measured during daily activities
Systolic blood pressure was not higher but use of blood pressure medications was higher with higher quartiles of homeostatic model assessment of insulin resistance (HOMA-IR) (Table 1); the relationship differed by quartiles of triglyceride and glucose index (TyG) (Supplemental Table 2, Additional file 1) and TG/ HDL-C (Supplemental Table 3, Additional file 1)
Low standard deviation of normal-to-normal R-R intervals (SDNN) was as likely at low insulin resistance indexes as at high insulin resistance indexes for HOMA-IR, TyG, and TG/HDL-C (OR: 1.35 (0.80, 2.29), odds ratios (OR): 1.33 (0.82, 2.17), OR: 1.30 (0.78, 2.14))
Summary
Prior studies have shown insulin resistance is associated with reduced cardiac autonomic function measured at rest, but few studies have determined whether insulin resistance is associated with reduced cardiac autonomic function measured during daily activities. Insulin resistance is a condition defined by a reduced response to insulin in target tissues [1]. It often precedes the development of the metabolic dysregulations and metabolic disorders that contribute to an increase in risk for cardiovascular disease [2,3,4,5]. Among adults without diabetes, heart rate variability is lower in adults with elevated insulin levels [10,11,12]. This evidence is based on shorter-term electrocardiogram recordings measured at rest. There is a limited understanding based on longer-term electrocardiogram recordings measured during daily activities
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
