Insulin sensitivity independently influences brachial-ankle pulse-wave velocity in non-diabetic subjects

Blood Haemoglobin Concentration Is Directly and Independently Related with Pulse Wave Velocity, a Measure of Large Artery Stiffness

High haemoglobin level has been associated with metabolic syndrome, elevated blood pressure (BP), and increased mortality risk. In this cross-sectional study, we investigated the association of blood haemoglobin with haemodynamics in 743 subjects, using whole-body impedance cardiography and pulse wave analysis. The participants were allocated to sex-stratified haemoglobin tertiles with mean values 135, 144, and 154 g/L, respectively. The mean age was similar in all tertiles, while body mass index was higher in the highest versus the lowest haemoglobin tertile. The highest haemoglobin tertile had the highest erythrocyte and leukocyte counts, plasma C-reactive protein, uric acid, renin activity, and aldosterone. The lipid profile was less favourable and insulin sensitivity lower in the highest versus the lowest haemoglobin tertile. Aortic BP, cardiac output, and systemic vascular resistance were similar in all tertiles, while the pulse wave velocity (PWV) was higher in the highest versus the lowest haemoglobin tertile. In linear regression analysis, age (Beta 0.478), mean aortic BP (Beta 0.178), uric acid (Beta 0.150), heart rate (Beta 0.148), and aldosterone-to-renin ratio (Beta 0.123) had the strongest associations with PWV (p < 0.001 for all). Additionally, haemoglobin concentration was an explanatory factory for PWV (Beta 0.070, p = 0.028). To conclude, blood haemoglobin concentration had a small direct and independent association with a measure of large artery stiffness.

One-Hour Post-Load Plasma Glucose Levels are Associated with Early Arterial Stiffness in Subjects with Different Glucose Tolerance

OBJECTIVE

The purpose of this study was to explore the relationship between one-hour post-load plasma glucose levels and early arterial stiffness in subjects with different glucose tolerance.

METHODS

This case-control study included 57 subjects with normal glucose tolerance, 38 subjects with pre-diabetes, and 30 subjects with type 2 diabetes. All subjects underwent an oral glucose tolerance test (OGTT) with 75 g of oral anhydrous glucose at 8:00 AM. The brachial-ankle pulse wave velocity (baPWV) was used as a surrogate marker of early arterial stiffness.

RESULTS

baPWV was significantly higher in the diabetes group than in the normal glucose tolerance group (diabetes group: 1501.8 ± 270.4 cm/s, pre-diabetes group: 1428.6 ± 173.1 cm/s vs normal glucose tolerance group: 1368.0 ± 242.8 cm/s) (p < 0.05). baPWV was positively correlated with age (r = 0.512, p < 0.001), systolic blood pressure (SBP) (r = 0.526, p < 0.001), diastolic blood pressure (DBP) (r = 0.298, p = 0.001), fasting plasma glucose (FPG) (r = 0.213, p = 0.017), 1-h plasma glucose levels from the OGTT (r = 0.407, p < 0.001) and 2-h plasma glucose levels from the OGTT (r = 0.202, p = 0.024). When baPWV was considered as the dependent variable in a multiple regression analysis, the 1-h plasma glucose level from the OGTT maintained an independent association with baPWV (β = 23.129, 95% CI: 8.142-38.115, p = 0.003, R² = 0.036).

CONCLUSION

The present study demonstrated the presence of early arterial stiffness in diabetes. Elevated 1-hour post-load plasma glucose level is closely related to the change of arterial elasticity in diabetes.

Association of hemoglobin with arterial stiffness evaluated by carotid-femoral pulse wave velocity among Chinese adults

Objective

Increased hemoglobin (Hb) levels are known to be associated with increased cardiovascular events and mortalities. Therefore, we assumed that high Hb levels were associated with arterial stiffness. Pulse wave velocity (PWV) is a simple and noninvasive method for measuring arterial stiffness to assess cardiovascular disease in general populations. Accordingly, we conducted a cross-sectional study to explore the association of Hb with PWV.

Methods

A total of 6642 adults aged 54.5 ± 11.2 years undergoing physical examinations were enrolled, 71.7% of whom were males. Arterial stiffness was evaluated by carotid-femoral PWV (cfPWV). Multivariable regression analyses were performed to determine the relationship between Hb and increased cfPWV.

Results

In this study, the mean Hb (per 10 g/L increase) was 144.7 ± 13.9 g/L, and the mean cfPWV was 15.1 ± 3.1 m/s. cfPWV was significantly higher in high hemoglobin groups ≥15.4 g/L (Quartile 4) than in the lowest hemoglobin group (Quartile 1 ≤ 13.6 g/L; P < 0.001). Multiple linear regression analysis revealed that Hb positively correlated with cfPWV (β = 0.16, P < 0.01). Univariate Logistic regression analysis revealed that Hb was associated with increased cfPWV, with an odd ratio (OR) of 1.46 (95% confidence interval [CI], 1.39–1.54). After adjusting for potential confounders, Hb and the highest Hb quartile group were also independently associated with increased cfPWV, with a fully adjusted OR of 1.11 (95% CI, 1.02–1.20) and 1.45 (95% CI, 1.01–2.08), respectively.

Conclusion

This study demonstrated that Hb levels significantly correlate with increased cfPWV.

Increased Arterial Stiffness in Adolescents With Obesity

Increased arterial stiffness (AS) is an early sign of cardiovascular disease. Influence of weight, puberty, and insulin resistance (IR) on AS in adolescents is unclear. Therefore, this study compared AS, assessed with pulse wave velocity (PWV) and augmentation index (AIx), of adolescents with and without obesity and evaluated the influence of puberty and IR on AS. Sixty-two lean and 61 adolescents with obesity were included. Significantly higher PWV was observed in adolescents with obesity (4.1 ms⁻¹ [2.4 to 5.6 ms⁻¹] vs 3.6 ms⁻¹ [0.4 to 6.1 ms⁻¹]; P = .01), while AIx was not significant different. However, significantly higher AIx was observed in adolescents with obesity and IR (3.0 [−17.5% to 28.5%] vs −3.0 [−19.0% to 13.0%]; P = .01). For Tanner stages, no differences were observed. The higher PWV in adolescents with obesity and higher AIx in adolescents with obesity and IR both indicate an increased AS. Consequently, measurement of AS should be considered in adolescents with obesity and IR as part of cardiovascular risk assessment.

Insulin resistance is associated with subclinical vascular disease in humans

Insulin resistance is associated with subclinical vascular disease that is not justified by conventional cardiovascular risk factors, such as smoking or hypercholesterolemia. Vascular injury associated to insulin resistance involves functional and structural damage to the arterial wall that includes impaired vasodilation in response to chemical mediators, reduced distensibility of the arterial wall (arterial stiffness), vascular calcification, and increased thickness of the arterial wall. Vascular dysfunction associated to insulin resistance is present in asymptomatic subjects and predisposes to cardiovascular diseases, such as heart failure, ischemic heart disease, stroke, and peripheral vascular disease. Structural and functional vascular disease associated to insulin resistance is highly predictive of cardiovascular morbidity and mortality. Its pathogenic mechanisms remain undefined. Prospective studies have demonstrated that animal protein consumption increases the risk of developing cardiovascular disease and predisposes to type 2 diabetes (T2D) whereas vegetable protein intake has the opposite effect. Vascular disease linked to insulin resistance begins to occur early in life. Children and adolescents with insulin resistance show an injured arterial system compared with youth free of insulin resistance, suggesting that insulin resistance plays a crucial role in the development of initial vascular damage. Prevention of the vascular dysfunction related to insulin resistance should begin early in life. Before the clinical onset of T2D, asymptomatic subjects endure a long period of time characterized by insulin resistance. Latent vascular dysfunction begins to develop during this phase, so that patients with T2D are at increased cardiovascular risk long before the diagnosis of the disease.

Utility of arterial stiffness assessment in children

Atherosclerotic cardiovascular disease is a leading cause of death and disability worldwide, and the atherosclerotic process begins in childhood. Prevention or containment of risk factors that accelerate atherosclerosis can delay the development of atherosclerotic cardiovascular disease. Although current recommendations are to periodically screen for commonly prevailing risk factors for atherosclerosis in children, a single test that could quantify the cumulative effect of all risk factors on the vasculature, thus assessing arterial health, would be helpful in further stratifying risk. Measurement of pulse wave velocity and assessment of augmentation index - measures of arterial stiffness - are easy-to-use, non-invasive methods of examining arterial health. Various studies have assessed pulse wave velocity and augmentation index in children with commonly occurring conditions including obesity, hypertension, insulin resistance, diabetes mellitus, dyslipidaemia, physical inactivity, chronic kidney disease, CHD and acquired heart diseases, and in children who were born premature or small for gestational age. This article summarises pulse wave velocity and augmentation index assessments and the effects of commonly prevailing chronic conditions on arterial health in children. In addition, currently available reference values for pulse wave velocity and augmentation index in healthy children are included. Further research to establish widely applicable normative values and the effect of lifestyle and pharmacological interventions on arterial health in children is needed.

Evaluation of function and structure of arterial wall in girls and young women with Turner syndrome

PURPOSE

Patients with Turner syndrome (TS) are frequently affected by congenital as well as acquired cardiovascular diseases. The aim of the study was to evaluate the blood pressure, the endothelial function (FMD) and the intima media thickness (IMT) at the level of the common carotid arteries in a group of girls and young women with TS in comparison to healthy controls.

METHODS

We evaluated 40 unselected TS patients, with a mean age of 18.6 ± 0.9 years and 103 age matched healthy subjects.

MAIN OUTCOME MEASURES

blood pressure, FMD and IMT.

RESULTS

No differences were found in systolic and diastolic blood pressure between TS patients and controls. FMD was higher in TS than in controls (14.2 ± 1.4 vs 11.4 ± 0.3%, p = 0.005) whereas IMT was not statistically different in the two study groups (0.54 ± 0.04 vs 0.57 ± 0.01 mm). However, in TS patients an inverse correlation was found between FMD and both age (-0.03 ± 0.01, p = 0.003) and years of estrogen therapy (-0.72 ± 0.31, p < 0.03), whereas a positive correlation was found between IMT and age (R 2 = 0.35, p < 0.0001) and estrogen therapy duration (R 2 = 0.65, p < 0.0001), suggesting a clear tendency toward a premature decrease in FMD and premature increase in IMT compared to controls.

CONCLUSIONS

Young TS patients show an arterial wall which is functionally and structurally comparable or better than controls. They show, however, a premature derangement of the arterial function and structure, which seems to be partly influenced by age and duration of oestrogen treatment.

Intrinsic Frequency and the Single Wave Biopsy: Implications for Insulin Resistance

Insulin resistance is the hallmark of classical type II diabetes. In addition, insulin resistance plays a central role in metabolic syndrome, which astonishingly affects 1 out of 3 adults in North America. The insulin resistance state can precede the manifestation of diabetes and hypertension by years. Insulin resistance is correlated with a low-grade inflammatory condition, thought to be induced by obesity as well as other conditions. Currently, the methods to measure and monitor insulin resistance, such as the homeostatic model assessment and the euglycemic insulin clamp, can be impractical, expensive, and invasive. Abundant evidence exists that relates increased pulse pressure, pulse wave velocity (PWV), and vascular dysfunction with insulin resistance. We introduce a potential method of assessing insulin resistance that relies on a novel signal-processing algorithm, the intrinsic frequency method (IFM). The method requires a single pulse pressure wave, thus the term " wave biopsy."

Association between the Postprandial Glucose Levels and Arterial Stiffness Measured According to the Cardio-ankle Vascular Index in Non-diabetic Subjects

OBJECTIVE

Although a relationship between post-challenge hyperglycemia and arterial stiffness has been reported, the relationship between the postprandial glucose levels and cardio-ankle vascular index (CAVI) in non-diabetic subjects is not clear. This study thus evaluated the association between the postprandial glucose levels after a composite meal and the degree of arterial stiffness measured according to CAVI in non-diabetic subjects.

METHODS

The subjects included 1,291 individuals (655 men and 636 women; mean age, 48.6 years; range, 23-85 years) who underwent medical examinations, including blood tests and CAVI assessments, between October 2005 and April 2012. The 1-hour postprandial glucose levels were determined after a 600-kcal traditional Japanese meal.

RESULTS

The CAVI values were significantly higher in the subjects with higher 1-hour postprandial glucose levels (≥140 mg/dL in men; ≥158 mg/dL in women). A simple regression analysis indicated that the CAVI values were significantly correlated with the 1-hour postprandial glucose levels in men (r=0.286, p<0.0001) and women (r=0.228, p<0.0001). After adjusting for age, BMI, systolic blood pressure, triglycerides, high-density lipoprotein cholesterol, low-density lipoprotein cholesterol, 1-hour postprandial glucose, homeostatis model assessment of insulin resistance, estimated glemerular filtration rate, and high sensitive C-reactive protein, stepwise multiple regression analysis demonstrated that the 1-hour postprandial glucose level was an independent predictor associated with the CAVI in men (p=0.003) and older women 50 years of age or older (p=0.003).

CONCLUSION

This study demonstrated that the 1-hour postprandial glucose levels are associated with increased CAVI values in non-diabetic men and older women 50 years of age or older.

Insulin resistance and arterial stiffness in healthy adolescents and young adults

AIMS/HYPOTHESIS

Increased arterial stiffness is a risk factor for adverse cardiovascular events in adults with obesity-related insulin resistance (IR) or type 2 diabetes mellitus. Adolescents with type 2 diabetes have stiffer vessels. Whether stiffness is increased in obesity/IR in youth is not known. We sought to determine if IR was a determinant of arterial stiffness in youth, independent of obesity and cardiovascular risk factors.

METHODS

We measured cardiovascular risk factors, IR, adipocytokines and arterial stiffness (brachial artery distensibility [BrachD], pulse wave velocity [PWV]) and wave reflection (augmentation index [AIx]) in 343 adolescents and young adults without type 2 diabetes (15-28 years old, 47% male, 48% non-white). Individuals <85th percentile of BMI were classified as lean (n = 232). Obese individuals were grouped by HOMA index as not insulin resistant (n = 46) or insulin resistant (n = 65) by the 90th percentile for HOMA for lean. Mean differences were evaluated by ANOVA. Multivariate models evaluated whether HOMA was an independent determinant of arterial stiffness.

RESULTS

Risk factors deteriorated from lean to obese to obese/insulin resistant (all p ≤ 0.017). Higher AIx, lower BrachD and higher PWV indicated increased arterial stiffness in obese and obese/insulin-resistant participants. HOMA was not an independent determinant. Age, sex, BMI and BP were the most consistent determinants, with HDL-cholesterol playing a role for BrachD and leptin for PWV (AIx R²= 0.34; BrachD R² = 0.37; PWV R² = 0.40; all p ≤ 0.02).

CONCLUSIONS/INTERPRETATION

Although IR is associated with increased arterial stiffness, traditional cardiovascular risk factors, especially obesity and BP, are the major determinants of arterial stiffness in healthy young people.

Profiles of atherosclerotic risk factors in gastrectomized men

Postprandial hyperglycemia is an established risk factor for atherosclerotic vascular diseases, and it is frequently observed in gastrectomized subjects. This study sought to examine whether other atherosclerotic risk factors are also common among gastrectomized subjects. The study population comprised of 44 non-diabetic men who previously underwent gastrectomy. The age- and body mass index-matched control population comprised of 278 non-diabetic men without gastrectomy. In addition to traditional atherosclerotic risk factors for atherosclerosis, high sensitivity C-reactive protein (hsCRP) and brachial-ankle pulse wave velocity (baPWV) were also compared between the groups. Fasting plasma glucose was not different between both groups, while glycated hemoglobin (HbA1c) was significantly higher in the gastrectomized men than in the control men. Systolic and diastolic blood pressures and high density lipoprotein cholesterol (HDL-C) were significantly higher, whereas low density lipoprotein cholesterol (LDL-C) was lower in the gastrectomized men than in the control men. baPWV, hsCRP, triglycerides and insulin resistance (as per the homeostasis model assessment) were not different between groups. While levels of certain atherosclerotic risk factors, including HbA1c and blood pressure are higher among gastrectomized men, HDL-C and LDL-C were actually favorable. Additionally, levels of more emerging risk factors, such as hsCRP and baPWV were not altered among gastrectomized men.

Insulin resistance independently influences arterial stiffness in normoglycemic normotensive postmenopausal women

OBJECTIVE

Cardiovascular disease risk increases after menopause, which may be related to insulin resistance, and arterial stiffness is a significant predictor of atherosclerosis. We investigated the relationships among insulin resistance, adiponectin, and arterial stiffness in normoglycemic normotensive postmenopausal women.

METHODS

From 9,555 participants who had routine health checkups, 455 normoglycemic normotensive postmenopausal women were enrolled. Serum concentrations of glucose, total cholesterol, triglyceride (TG), and high-density lipoprotein cholesterol (HDL-C) and adiponectin were measured. Insulin resistance was estimated by the insulin resistance index of homeostasis model assessment (HOMA-IR). Pulse wave velocity (PWV) was evaluated to assess arterial stiffness.

RESULTS

The women were stratified into three groups according to their HOMA-IR values, and comparisons were made among the three groups. There were significant differences in metabolic parameters between the groups. The mean age, body mass index, waist circumference, fasting plasma glucose, TG, systolic blood pressure (SBP), diastolic blood pressure (DBP), aortic PWV, and peripheral PWV increased sequentially with the degree of insulin resistance. Meanwhile, HDL-C and adiponectin levels decreased with the worsening of insulin resistance. Age, body mass index, fasting plasma glucose, TG, insulin, SBP, HOMA-IR, aortic PWV, and peripheral PWV were significantly higher in women with central obesity, and HDL-C and adiponectin were significantly lower in women with central obesity. Aortic PWV and peripheral PWV were significantly correlated with age, waist circumference, total cholesterol, SBP, DBP, insulin, and HOMA-IR, but adiponectin was not associated with PWV. The results of multiple regression analysis indicated that SBP, DBP, and insulin resistance were independently correlated with PWV.

CONCLUSIONS

Insulin resistance was independently associated with PWV in normoglycemic normotensive postmenopausal women.

The association of brachial-ankle pulse wave velocity with 30-minute post-challenge plasma glucose levels in korean adults with no history of type 2 diabetes

Background

Acute postprandial hyperglycemia is an important affector for atherosclerosis in subjects with glucose intolerance. We analyzed the relationship of brachial-ankle pulse wave velocity (baPWV) with fasting and post-challenge plasma glucose levels according to different time points during oral glucose tolerance test (OGTT).

Methods

In 663 subjects with fasting hyperglycemia, 75 g OGTT were performed to confirm the glucose tolerant status, and fasting, post-challenge 30-minute and 120-minute glucose levels were measured. Anthropometric measurements were done, and fasting lipid profiles were measured. baPWV were measured in all subjects and the relationship between fasting, 30- and 120-minute post-challenge glucose levels and baPWV were analyzed.

Results

Among the participants, 62.9% were prediabetes and 31.7% were diabetes. Mean baPWV value was significantly higher in subjects with diabetes compared with prediabetes group. In bivariate correlation analyses, age, blood pressure, total cholesterol, low density lipoprotein cholesterol, 30-minute and 120-minute post-challenge glucose levels showed significant positive correlation with baPWV value. In multiple regression analysis, 30-minute post-challenge glucose level was a weak but significant determinant for mean baPWV value even after adjustment for other confounding variables.

Conclusions

Postprandial hyperglycemia, especially 30-minute glucose levels showed significant correlation with baPWV in subjects with fasting hyperglycemia. These results can imply the deleterious effect of acute hyperglycemic excursion on arterial stiffness in subjects with glucose intolerance.

Home-based resistance training improves arterial stiffness in healthy premenopausal women

The present study investigates the effect of home-based resistance training on arterial stiffness in healthy premenopausal women. Twelve healthy non-smoking and normotensive women who were not actively involved in regular physical exercise (aged 42-55 years) performed home-based resistance training twice weekly for 10 weeks using body weight and light dumbbells. Each training session required approximately 40 min to complete. Arterial stiffness was measured using brachial-ankle pulse wave velocity (baPWV). We also determined serum total cholesterol, HDL cholesterol, glucose, triglyceride, insulin, and adiponectin and calculated the homeostasis model assessment of insulin resistance (HOMA-IR), an index of insulin resistance. After home-based resistance training, baPWV, total cholesterol, LDL cholesterol, insulin, and the HOMA-IR decreased, whereas adiponectin increased (P < 0.05) and levels of HDL cholesterol, glucose, triglyceride, blood pressure, and heart rate remained unaffected. These results suggest that home-based resistance training benefits vascular function in healthy premenopausal women.

Menopause, the metabolic syndrome, and mind-body therapies

Cardiovascular disease risk rises sharply with menopause, likely due to the coincident increase in insulin resistance and related atherogenic changes that together comprise the metabolic or insulin resistance syndrome, a cluster of metabolic and hemodynamic abnormalities strongly implicated in the pathogenesis and progression of cardiovascular disease. A growing body of research suggests that traditional mind-body practices such as yoga, tai chi, and qigong may offer safe and cost-effective strategies for reducing insulin resistance syndrome-related risk factors for cardiovascular disease in older populations, including postmenopausal women. Current evidence suggests that these practices may reduce insulin resistance and related physiological risk factors for cardiovascular disease; improve mood, well-being, and sleep; decrease sympathetic activation; and enhance cardiovagal function. However, additional rigorous studies are needed to confirm existing findings and to examine long-term effects on cardiovascular health.

Effects of IL-6, adiponectin, CRP and metabolic syndrome on subclinical atherosclerosis

BACKGROUND

Inflammation has been implicated in the pathogenesis of cardiovascular disease. Since there have been few studies elucidating gender-specific effect of inflammation and metabolic syndrome (MetS) on subclinical atherosclerosis, we evaluated the relative contribution of these factors in healthy subjects.

METHODS

MetS components, carotid intima-media thickness (IMT) and pulse wave velocity (PWV) were evaluated in apparently healthy 714 men and 364 women (40-59 y). Serum levels of high sensitive C-reactive protein (hs-CRP), interleukin-6 (IL-6) and adiponectin were also examined.

RESULTS

Increase in number of clustering MetS components was more clearly associated with worsening of IMT and PWV in women than in men. Serum IL-6 level was positively correlated with IMT and PWV, and adiponectin level was negatively correlated with IMT in men but not in women. The subjects either with a "high" IL-6 or hs-CRP, or a "low" adiponectin were associated with increase in IMT in the presence of MetS, though there was no significant effect of MetS in those with low inflammation.

CONCLUSIONS

While IL-6 and adiponectin are the important risk factors for early arterial alterations in men, components of MetS present profound effects on subclinical atherosclerosis in women rather than in men.