Relatively lower central aortic pressure in patients with impaired insulin sensitivity and resistance: the Toon Health Study

Interaction effect between low birthweight and resistin gene rs1862513 variant on insulin resistance and type 2 diabetes mellitus in adulthood: Toon Genome Study

AIMS/INTRODUCTION

Gene-environment interactions are considered to critically influence type 2 diabetes mellitus development; however, the underlying mechanisms and specific interactions remain unclear. Given the increasing prevalence of low birthweight (LBW) influenced by the intrauterine environment, we sought to investigate genetic factors related to type 2 diabetes development in individuals with LBW.

MATERIALS AND METHODS

The interaction between 20 reported type 2 diabetes susceptibility genes and the development of type 2 diabetes in LBW (<2,500 g) individuals in a population-based Japanese cohort (n = 1,021) was examined by logistic regression and stratified analyses.

RESULTS

Logistic regression analyses showed that only the G/G genotype at the rs1862513 locus of the resistin gene (RETN), an established initiator of insulin resistance, was closely related to the prevalence of type 2 diabetes in individuals with LBW. Age, sex and current body mass index-adjusted stratified analyses showed a significant interaction effect of LBW and the RETN G/G genotype on fasting insulin, homeostatic model assessment 2-insulin resistance, Matsuda index and the prevalence of type 2 diabetes (all P-values for interaction <0.05). The adjusted odds ratio for type 2 diabetes in the LBW + G/G genotype group was 7.33 (95% confidence interval 2.43-22.11; P = 0.002) compared with the non-LBW + non-G/G genotype group. Similar results were obtained after excluding the influence of malnutrition due to World War II.

CONCLUSIONS

Simultaneous assessment of LBW and the RETN G/G genotype can more accurately predict the risk of future type 2 diabetes than assessing each of these factors alone, and provide management strategies, including early lifestyle intervention in LBW population.

Low birthweight is associated with type 2 diabetes mellitus in Japanese adults: The Toon Health Study

Aims/Introduction

Low birthweight is reportedly associated with type 2 diabetes mellitus; however, this association has not been confirmed in the Japanese population, and whether high birthweight is associated with type 2 diabetes mellitus is controversial. We aimed to investigate the association between birthweight and type 2 diabetes mellitus among a general Japanese population.

Materials and Methods

Overall 1,135 middle‐ to old‐aged Japanese men and women were enrolled in the Toon Health Study. A 75‐g oral glucose tolerance test was used to diagnose type 2 diabetes mellitus, and a questionnaire survey about birthweight was administered. The association between birthweight and the prevalence of type 2 diabetes mellitus in later life of the participants was examined using multivariable logistic regression analysis. Stratified analysis by current body mass index was also carried out.

Results

The mean age was 56.5 ± 12.2 years. Type 2 diabetes mellitus was observed in 9.3% of the participants in this study. Compared with the reference group (2,500–3,999 g), the adjusted odds ratio of the low‐birthweight group (<2,500 g) for type 2 diabetes mellitus was 2.46 (95% confidence interval 1.48–4.10). The association between the high‐birthweight group (≥4000 g) and type 2 diabetes mellitus was not significant after including family history of diabetes in the multivariable model. The odds ratio of the low‐birthweight group for type 2 diabetes mellitus was higher in the overweight/obese group than in the non‐overweight group.

Conclusions

Low birthweight was associated with an increased risk of type 2 diabetes mellitus in a Japanese population, especially in overweight/obese individuals.

Relationships between serum free fatty acid and pulse pressure amplification in overweight/obese men: insights from exercise training and dietary modification

Pulse pressure amplification (i.e., the ratio of peripheral to central pulse pressure) is a strong predictor of cardiovascular events. Circulating free fatty acid, which is a major cause of insulin resistance, has been reported to favorably be associated with pulse pressure amplification in the arm (from the aorta to brachial artery). We hypothesized that this paradoxical relationship depended on an evaluating site of pulse pressure amplification and investigated whether serum free fatty acid level is related to pulse pressure amplification in the arm or trunk (from the aorta to femoral artery) in overweight/obese men. In a cross-sectional study, 85 men participated, and regression analyses revealed that serum free fatty acid level was significantly and independently associated with pulse pressure amplification in the arm but not the trunk. In a longitudinal study, 33 men completed a 12-week lifestyle intervention that involved both exercise training and dietary modification. The lifestyle intervention-induced change in serum free fatty acid level was significantly correlated to that in pulse pressure amplification in the arm but not the trunk. These results support our hypothesis and suggest that pulse pressure amplification should be measured in the trunk instead of the arm in overweight/obese men to simplify its interpretation.

Relationships between serum free fatty acid and pulse pressure amplification in overweight/obese men: insights from exercise training and dietary modification

Pulse pressure amplification (i.e., the ratio of peripheral to central pulse pressure) is a strong predictor of cardiovascular events. Circulating free fatty acid, which is a major cause of insulin resistance, has been reported to favorably be associated with pulse pressure amplification in the arm (from the aorta to brachial artery). We hypothesized that this paradoxical relationship depended on an evaluating site of pulse pressure amplification and investigated whether serum free fatty acid level is related to pulse pressure amplification in the arm or trunk (from the aorta to femoral artery) in overweight/obese men. In a cross-sectional study, 85 men participated, and regression analyses revealed that serum free fatty acid level was significantly and independently associated with pulse pressure amplification in the arm but not the trunk. In a longitudinal study, 33 men completed a 12-week lifestyle intervention that involved both exercise training and dietary modification. The lifestyle intervention-induced change in serum free fatty acid level was significantly correlated to that in pulse pressure amplification in the arm but not the trunk. These results support our hypothesis and suggest that pulse pressure amplification should be measured in the trunk instead of the arm in overweight/obese men to simplify its interpretation.

Perspective: Cardiovascular Responses to Sugar-Sweetened Beverages in Humans: A Narrative Review with Potential Hemodynamic Mechanisms

Cardiovascular diseases are still the primary cause of mortality worldwide, with high blood pressure and type 2 diabetes as major promoters. Over the past 3 decades, almost in parallel with the rise in cardiovascular disease incidence, the consumption of sugar-sweetened beverages (SSBs) has increased. In this context, SSBs are potential contributors to weight gain and increase the risk for elevations in blood pressure, type 2 diabetes, coronary heart disease, and stroke. Nevertheless, the mechanisms underlying the cardiovascular and metabolic responses to SSBs, in particular on blood pressure, are poorly understood. We discuss and propose potential mechanisms underlying differential effects of sugars on postprandial blood pressure regulation; provide evidence for additional molecular contributors, i.e., fibroblast growth factor 21, towards sugar-induced cardiovascular responses; and discuss potential cardiovascular neutral sugars. Furthermore, we explore whether pre-existing glucose intolerance in humans exacerbates the cardiovascular responses to SSBs, thus potentially aggravating the cardiovascular risk in already-susceptible individuals.

Cardiovascular Risk Factors and Disease Characteristics Are Consistently Associated with Arterial Function in Rheumatoid Arthritis

Objective.

Arterial properties influence cardiovascular disease (CVD) risk. We identified potential determinants of arterial function in patients with rheumatoid arthritis (RA).

Methods.

Relationships of traditional cardiovascular risk factors and RA characteristics with arterial stiffness (pulse wave velocity), wave reflection (augmentation index, reflected wave pressure, and reflection magnitude), and pressure pulsatility (central systolic and pulse pressure, peripheral pulse pressure, pulse pressure amplification, and forward wave pressure) were identified in multivariable backward regression models among 177 patients without established CVD (118 white, 32 Asian, 22 black, 5 mixed ancestry).

Results.

Recorded characteristics explained 37% (pulse wave velocity) to 71% (reflected wave pressure) of the variability in arterial function. These factors were particularly associated with wave reflection and pressure pulsatility: RA duration (p = 0.04), rheumatoid factor status (p = 0.01 to 0.03), leukocyte counts (p = 0.02 to 0.05), and total cholesterol (p < 0.01 to 0.03). Body mass index (p < 0.01 to 0.02) and insulin resistance (p < 0.01 to 0.01) were related to reduced wave reflection and peripheral pulse pressure. Exercise (p = 0.02) and alcohol consumption (p < 0.01) were associated with increased pulse pressure amplification and decreased peripheral pulse pressure, respectively. Tumor necrosis factor-α inhibition (p < 0.01) was related to reduced pulse wave velocity, and tetracycline use (p = 0.02) to decreased peripheral pulse pressure.

Conclusion.

Traditional cardiovascular risk factors and disease characteristics are consistently associated with vascular hemodynamic alterations in RA. The relative effect of arterial stiffness, wave reflection, and pressure pulsatility on CVD risk in RA needs further study.

Which Measurement of Blood Pressure Is More Associated With Albuminuria in Patients With Type 2 Diabetes: Central Blood Pressure or Peripheral Blood Pressure?

The aim of this study was to investigate whether central systolic blood pressure (SBP) was associated with albuminuria, defined as urinary albumin excretion (UAE) ≥30 mg/g creatinine, and, if so, whether the relationship of central SBP with albuminuria was stronger than that of peripheral SBP in patients with type 2 diabetes. The authors performed a cross-sectional study in 294 outpatients with type 2 diabetes. The relationship between peripheral SBP or central SBP and UAE using regression analysis was evaluated, and the odds ratios of peripheral SBP or central SBP were calculated to identify albuminuria using logistic regression model. Moreover, the area under the receiver operating characteristic curve (AUC) of central SBP was compared with that of peripheral SBP to identify albuminuria. Multiple regression analysis demonstrated that peripheral SBP (β=0.255, P<.0001) or central SBP (r=0.227, P<.0001) was associated with UAE. Multiple logistic regression analysis demonstrated that peripheral SBP (odds ratio, 1.029; 95% confidence interval, 1.016-1.043) or central SBP (odds ratio, 1.022; 95% confidence interval, 1.011-1.034) was associated with an increased odds of albuminuria. In addition, AUC of peripheral SBP was significantly greater than that of central SBP to identify albuminuria (P=0.035). Peripheral SBP is superior to central SBP in identifying albuminuria, although both peripheral and central SBP are associated with UAE in patients with type 2 diabetes.

Heart Rate Variability, Insulin Resistance, and Insulin Sensitivity in Japanese Adults: The Toon Health Study

BACKGROUND

Although impaired cardiac autonomic function is associated with an increased risk of type 2 diabetes in Caucasians, evidence in Asian populations with a lower body mass index is limited.

METHODS

Between 2009-2012, the Toon Health Study recruited 1899 individuals aged 30-79 years who were not taking medication for diabetes. A 75-g oral glucose tolerance test was used to diagnose type 2 diabetes, and fasting and 2-h-postload glucose and insulin concentrations were measured. We assessed the homeostasis model assessment index for insulin resistance (HOMA-IR) and Gutt's insulin sensitivity index (ISI). Pulse was recorded for 5 min, and time-domain heart rate variability (HRV) indices were calculated: the standard deviation of normal-to-normal intervals (SDNN) and the root mean square of successive difference (RMSSD). Power spectral analysis provided frequency domain measures of HRV: high frequency (HF) power, low frequency (LF) power, and the LF:HF ratio.

RESULTS

Multivariate-adjusted logistic regression models showed decreased SDNN, RMSSD, and HF, and increased LF:HF ratio were associated significantly with increased HOMA-IR and decreased ISI. When stratified by overweight status, the association of RMSSD, HF, and LF:HF ratio with decreased ISI was also apparent in non-overweight individuals. The interaction between LF:HF ratio and decreased ISI in overweight individuals was significant, with the odds ratio for decreased ISI in the highest quartile of LF:HF ratio in non-overweight individuals being 2.09 (95% confidence interval, 1.41-3.10).

CONCLUSIONS

Reduced HRV was associated with insulin resistance and lower insulin sensitivity. Decreased ISI was linked with parasympathetic dysfunction, primarily in non-overweight individuals.

Arterial stiffness after glucose ingestion in exercise-trained versus untrained men

Postprandial hyperglycemia increases arterial stiffness. Arterial stiffness and insulin resistance are lower in exercise-trained humans than in untrained humans. However, the effect of exercise on arterial stiffness after glucose ingestion in young adults remains unknown. The present study investigates the effect of regular aerobic exercise on arterial stiffness after glucose ingestion in young males. Ten exercise-trained males (age, 20.8 ± 0.2 years; ETR) and 9 healthy untrained males (age, 22.2 ± 0.7 years; UTR) participated in this study. Carotid-femoral (aortic) pulse wave velocity (PWV), femoral-ankle (leg) PWV, carotid augmentation index (AIx) (applanation tonometry), brachial and ankle blood pressure (BP), heart rate (oscillometric device and electrocardiography), and blood glucose (glucose oxidase method) were measured at 30 min before (baseline) and 30, 60, and 120 min after a 75-g oral glucose tolerance test. Leg PWV at 30 min after glucose ingestion was significantly higher (P < 0.01) in the UTR group than in the ETR group. Ankle systolic BP at 30 min after glucose ingestion was also significantly higher in the UTR group than in the ETR group (P < 0.05). Blood glucose increased from baseline at 30 min (P < 0.01) and 60 min (P < 0.05) after glucose ingestion in both groups. Aortic PWV, carotid AIx, and brachial systolic BP did not change from baseline after glucose ingestion in both groups. The present findings indicate that leg PWV and ankle systolic BP after glucose ingestion were significantly lower in the ETR group than in the UTR group.

The impact of masticatory ability as evaluated by salivary flow rates on obesity in Japanese: The Toon health study

OBJECTIVE

This study examined the associations of masticatory ability evaluated by chewing-gum-stimulated salivary flow rate with anthropometric indices among a general Japanese population.

METHODS

In total, 921 Japanese men and women aged 30-79 years participated in this cross-sectional study. Saliva production was stimulated by 5 min of gum chewing, then collected; salivary flow rate was calculated as g/min. Overweight, abdominal obesity in terms of waist circumference (WC), and waist-hip ratio (WHR), and elevated skinfold thickness statuses were determined.

RESULTS

The multivariable odds ratio and 95% confidence intervals of overweight, abdominal obesity (WC, WHR), and elevated skinfold thickness status for highest vs. lowest quartile of salivary flow rate were 0.59 (0.37-0.95, P for trend = 0.02), 0.65 (0.43-0.98, P = 0.03), 0.54 (0.35-0.83, P < 0.01), and 0.61 (0.39-0.96, P < 0.01), respectively. The linear trends of multivariable-adjusted means of BMI, WC, WHR, and skinfold thickness according to quartiles of salivary flow rate did not vary after stratification by overweight status.

CONCLUSIONS

Higher stimulated salivary flow rate, a surrogate marker for mastication ability, was associated with lower prevalence of overweight, abdominal obesity (whether WC- or WHR-defined), and elevated skinfold thickness among the general Japanese population.

Associations of serum β-carotene and retinol concentrations with insulin resistance: the Toon Health Study

OBJECTIVE

Although green and yellow vegetables have beneficial effects against type 2 diabetes, the relationship of their nutritive content with insulin resistance is poorly understood. The aim of this study was to examine the associations of serum β-carotene and retinol concentrations with glucose and insulin concentrations.

METHODS

We recruited 951 Japanese men and women ages 30 to 79 y who were not undergoing treatment for diabetes and measured their serum β-carotene and retinol concentrations. A 75-g oral glucose tolerance test was performed and the homeostasis model assessment for insulin resistance (HOMA-IR) and the Matsuda Index were calculated as measures of insulin resistance. Several confounding factors were adjusted for with multivariable logistic models.

RESULTS

Multivariable-adjusted odds ratios of the highest quartile of serum β-carotene compared with the lowest quartile for HOMA-IR >1.6 and Matsuda Index <4.9 were 0.56 (95% confidence interval, 0.34-0.94) and 0.62 (0.37-1.02), respectively. When stratified by sex and overweight status, these associations were observed for women and non-overweight individuals. Serum retinol concentration was not associated with either index. Furthermore, according to the nutritional survey, serum β-carotene concentration was associated with green and yellow vegetable intake (P = 0.01).

CONCLUSION

Our findings suggest that higher serum β-carotene levels, associated with higher intake of green and yellow vegetables, confer beneficial effects against insulin resistance.

Association of serum-free fatty acid level with reduced reflection pressure wave magnitude and central blood pressure: the Nagahama study

Central blood pressure (BP) has been suggested to be a better predictor of cardiovascular disease risk than brachial BP. Given that central BP and arterial waveform are both influenced by insulin resistance, major initiators of insulin resistance, such as serum-free fatty acid (FFA), are suspected of potentially being involved in central hemodynamics. To confirm that insulin signaling is an important modulator of central hemodynamics, we investigated this hypothesis in a large-scale general population. Brachial BP and radial arterial waveform were measured simultaneously in 9393 middle-aged to elderly individuals. The augmentation index was calculated from the radial waveform as the ratio of the height of the late systolic peak to that of the first peak. Central systolic BP was defined as the absolute pressure of the late systolic peak of the waveform. Differences in central and brachial pulse pressure (PP) were considered to represent PP amplification. PP amplification differed significantly among serum FFA level quartiles (Q1, 7.8±5.3; Q2, 8.6±5.0; Q3, 9.3±5.7; Q4, 10.3±6.1 mm Hg; P<0.001), and the maximum difference in combination with diabetes mellitus status was 4.9 mm Hg. Multivariate analysis adjusted for major covariates indicated that higher serum FFA was an independent determinant for higher PP amplification (β=0.145, P<0.001) and lower augmentation index (β=-0.122, P<0.001) and central systolic BP (β=-0.044, P<0.001), whereas the association between FFA and PP amplification significantly decreased (β=0.022, P<0.001) after further adjustment for augmentation index. Serum FFA is an overlooked factor favorably influencing central hemodynamics. A low-magnitude reflection pressure wave might be involved in this paradoxical relationship.

Effect of weight loss on central systolic blood pressure in elderly community-dwelling persons

Central blood pressure (BP) has been shown to strongly associate with cardiovascular disease and outcome. Recent studies have demonstrated a relationship between changes in body size by exercise training and peripheral BP; however, the effect on changes in central BP is unknown. The aim of this study was to assess whether changes in body size are independently related to changes in central BP in the elderly. The subjects were 11 men (mean age, 68±6 years) and 84 women (68±7 years) from a rural village. Before and at the end of the 12-week training program, metabolic variables, and first peak radial systolic BP (SBP1) and second peak radial SBP (SBP2) as estimates of central SBP, were obtained. Radial augmentation index (AI) was calculated as follows: ((SBP2-diastolic BP (DBP))/(SBP1-DBP)) × 100 (%) and we used AI corrected at heart rate 75 per min (AI@75). After the 12-week training program, weight loss correlated strongly with reduction in brachial mean arterial pressure (MAP), radial SBP1, SBP2 and AI@75. After adjusting for confounding factors, weight loss was significantly and independently associated with each reduction in brachial MAP (β=0.34, P=0.001), radial SBP1 (β=0.31, P=0.002), SBP2 (β=0.37, P<0.001) and AI@75 (β=0.36, P=0.001). These findings suggest that weight loss by a 12-week training program may be an effective strategy to improve central BP parameters among Japanese elderly persons.

An association between central aortic pressure and subclinical organ damage of the heart among a general Japanese cohort: Circulatory Risk in Communities Study (CIRCS)

BACKGROUND

This study aimed to investigate associations between central aortic pressure (CAP) and subclinical organ damage of the heart amongst the general population.

METHODS

We conducted a cross-sectional study in a community-based population, consisting of 3002 men and women aged between 40 and 79 years. The CAP was measured using the HEM-9000AI device, an automated tonometer. Electrocardiograms (ECG) were read according to the Minnesota Code. Subclinical organ damage in the heart was defined as measurable left high amplitude R waves (LHAR), major and minor ST-T abnormalities, and left ventricular hypertrophy (LVH).

RESULTS

Age- and sex-adjusted prevalence of LHAR, major and minor ST-T abnormalities, and LVH was higher for subjects in the highest tertile of CAP levels than those in the lowest tertile. After further adjustments for other cardiovascular risk factors, these associations did not change substantially. The multivariable odds ratios (ORs) (95% CI) of LHAR, major and minor ST-T abnormalities, and LVH for the highest tertile of CAP levels compared to the lowest tertile were 2.7(1.9-3.9), 1.8(1.1-2.9), 1.7(1.3-2.3) and 3.2(1.3-8.1), respectively. The positive associations with LHAR and minor ST-T abnormalities were observed primarily among non-hypertensive subjects. The respective corresponding ORs were 2.8(1.7-4.6) and 1.7(1.2-2.4) for non-hypertensive subjects, and 1.7(0.9-3.3) and 1.1(0.7-1.8) for hypertensive subjects.

CONCLUSION

CAP levels were associated with subclinical organ damage of the heart independent of cardiovascular risk factors, and these associations were primarily seen in non-hypertensive subjects.

Association of longer QT interval with arterial waveform and lower pulse pressure amplification: the Nagahama Study

BACKGROUND

Central systolic blood pressure (cSBP) has been postulated to correlate closely with cardiovascular risk. Identifying factors associated with cSBP is therefore important. Prolonged QT interval is known to be associated with cardiovascular outcomes and might also be associated with the arterial waveform and cSBP. We investigated the possible associations between electrocardiogram wave interval and cSBP in general population samples.

METHODS

Brachial blood pressure and radial arterial waveform were measured simultaneously. Augmentation index (AIx) was calculated from the radial waveform as the ratio of the height of the late systolic peak to that of the first peak. cSBP was defined as the absolute pressure of the late systolic peak.

RESULTS

In the first panel (n = 8,085), QT interval was strongly association with AIx (r = 0.330; P < 0.001). This association remained significant even in the heart rate-adjusted analysis (r = 0.184; P < 0.001). Although subjects with a longer QT interval were older and had higher blood pressure, heart rate, and pulse wave velocity, multivariable analysis with adjustment for these covariables nevertheless identified longer corrected QT interval as an independent determinant of increased AIx and smaller pulse pressure amplification (PPa; brachial SBP minus cSBP) (β = -0.066; P < 0.001). This association was replicated in the independent second panel (n = 1,412) (β = -0.105; P < 0.001). In contrast, QRS interval was positively associated with PPa (β = 0.056; P < 0.001).

CONCLUSIONS

Longer QT interval and short QRS duration were significantly associated with arterial waveform and PPa. Our results provide a clue to the elucidation of unidentified mechanisms of the increased cardiovascular outcome and mortality risks in subjects with longer QT interval.