@article {1008, title = {Higher levels of inflammation factors and greater insulin resistance are independently associated with higher heart rate and lower heart rate variability in normoglycemic older individuals: the Cardiovascular Health Study.}, journal = {J Am Geriatr Soc}, volume = {56}, year = {2008}, month = {2008 Feb}, pages = {315-21}, abstract = {

OBJECTIVES: To explore the relationship between (1) insulin resistance and inflammation factors with (2) higher heart rate (HR) and lower heart rate variability (HRV) in normoglycemic older adults.

DESIGN: Cross-sectional population-based study.

PARTICIPANTS: Five hundred forty-five adults aged 65 and older with normoglycemia (fasting glucose <100 mg/dL) who participated in the Cardiovascular Health Study.

MEASUREMENTS: Serum levels of three inflammation proteins (C-reactive protein (CRP), interleukin 6 (IL-6), and fibrinogen); insulin resistance, quantified according to the homeostasis assessment model (HOMA-IR); HR; and four representative measures of HRV (the standard deviation of normal beat to beat intervals (SDNN), the root mean square of successive differences (rMSSD), very low frequency power (VLF), and the low- to high-frequency power ratio (LF/HF)) derived from 24-hour Holter recordings.

RESULTS: High CRP and IL-6 levels were associated with higher HR and lower SDNN and VLF after adjustment for multiple covariates, including HOMA-IR and clinical cardiovascular disease. High IL-6 was also associated with lower LF/HF. Significant univariate inverse relationships between HOMA-IR and HR and HRV were also found, but the strengths of these relationships were attenuated after adjustment for inflammation factors.

CONCLUSION: Increased levels of inflammation markers and HOMA-IR are associated with higher HR and lower HRV. These findings suggest that inflammation may contribute to the pathogenesis of cardiovascular autonomic decline in older adults.

}, keywords = {Aged, C-Reactive Protein, Cardiovascular Diseases, Cross-Sectional Studies, Electrocardiography, Ambulatory, Female, Fibrinogen, Heart Rate, Humans, Inflammation Mediators, Insulin Resistance, Interleukin-6, Male, Risk Factors}, issn = {1532-5415}, doi = {10.1111/j.1532-5415.2007.01564.x}, author = {Stein, Phyllis K and Barzilay, Joshua I and Chaves, Paulo H M and Traber, Jennifer and Domitrovich, Peter P and Heckbert, Susan R and Gottdiener, John S} } @article {1339, title = {Fasting and post-glucose load measures of insulin resistance and risk of ischemic stroke in older adults.}, journal = {Stroke}, volume = {42}, year = {2011}, month = {2011 Dec}, pages = {3347-51}, abstract = {

BACKGROUND AND PURPOSE: Few studies have assessed post-glucose load measures of insulin resistance and ischemic stroke risk, and data are sparse for older adults. We investigated whether fasting and post-glucose load measures of insulin resistance were related to incident ischemic stroke in nondiabetic, older adults.

METHODS: Participants were men and women in the Cardiovascular Health Study, age 65+ years and without prevalent diabetes or stroke at baseline, followed for 17 years for incident ischemic stroke. The Gutt insulin sensitivity index was calculated from baseline body weight and from fasting and 2-hour postload insulin and glucose; a lower Gutt index indicates higher insulin resistance.

RESULTS: Analyses included 3442 participants (42\% men) with a mean age of 73 years. Incidence of ischemic stroke was 9.8 strokes per 1000 person-years. The relative risk (RR) for lowest quartile versus highest quartile of Gutt index was 1.64 (95\% CI, 1.24-2.16), adjusted for demographics and prevalent cardiovascular and kidney disease. Similarly, the adjusted RR for highest quartile versus lowest quartile of 2-hour glucose was 1.84 (95\% CI, 1.39-2.42). In contrast, the adjusted RR for highest quartile versus lowest quartile of fasting insulin was 1.10 (95\% CI, 0.84-1.46).

CONCLUSIONS: In nondiabetic, older adults, insulin resistance measured by Gutt index or 2-hour glucose, but not by fasting insulin, was associated with risk of incident ischemic stroke.

}, keywords = {Aged, Aged, 80 and over, Blood Glucose, Body Mass Index, Brain Ischemia, Fasting, Female, Humans, Incidence, Insulin Resistance, Male, Risk, Stroke}, issn = {1524-4628}, doi = {10.1161/STROKEAHA.111.620773}, author = {Thacker, Evan L and Psaty, Bruce M and McKnight, Barbara and Heckbert, Susan R and Longstreth, W T and Mukamal, Kenneth J and Meigs, James B and de Boer, Ian H and Boyko, Edward J and Carnethon, Mercedes R and Kizer, Jorge R and Tracy, Russell P and Smith, Nicholas L and Siscovick, David S} }