Validity and reproducibility of HOMA-IR, 1/HOMA-IR, QUICKI and McAuley's indices in patients with hypertension and type II diabetes

The aim of this study was to evaluate the validity and reliability of homeostasis model assessment-insulin resistance (HOMA-IR) index, its reciprocal (1/HOMA-IR), quantitative insulin sensitivity check index (QUICKI) and McAuley's index in hypertensive diabetic patients. In 78 patients with hypertension and type II diabetes glucose, insulin and triglyceride levels were determined after a 12-h fast to calculate these indices, and insulin sensitivity (IS) was measured with the hyperinsulinemic euglycemic clamp technique. Two weeks later, subjects had again their glucose, insulin and triglycerides measured. Simple and multiple linear regression analysis were applied to assess the validity of these indices compared to clamp IS and coefficients of variation between the two visits were estimated to assess their reproducibility. HOMA-IR index was strongly and inversely correlated with the basic IS clamp index, the M-value (r = 0.572, P < 0.001), M- value normalized with subjects' body weight or fat-free mass and every other clamp-derived index. 1/HOMA-IR and QUICKI indices were positively correlated with the M- value (r = 0.342, P < 0.05 and r = 0.456, P < 0.01, respectively) and the rest clamp indices. McAuley's index generally presented less strong correlations ( r = 0.317, P < 0.05 with M- value). In multivariate analysis, HOMA-IR was the best fit of clampderived IS. Coefficients of variation between the two visits were 23.5% for HOMA-IR, 19.2% for 1/HOMA-IR, 7.8% for QUICKI and 15.1% for McAuley's index. In conclusion, HOMA- IR, 1/HOMA-IR and QUICKI are valid estimates of clamp-derived IS in patients with hypertension and type II diabetes, whereas the validity of McAuley's index needs further evaluation. QUICKI displayed better reproducibility than the other indices

Wave reflections and systemic vascular resistance are stronger determinants of pulse pressure amplification than aortic stiffness in drug-naïve hypertensives

Background: Aortic-to-brachial pulse pressure (PP) amplification is a novel biomarker that prognosticates the cardiovascular risk above and beyond central aortic and brachial blood pressure. This phenomenon is modulated by left ventricular contractility and chronotrophy, large-artery stiffness and reflecting properties of microcirculation. However, the relative importance of these parameters as hemodynamic determinant of PP amplification remains elusive. Methods: A total of 88 consecutive drug-naïve hypertensives underwent a non-invasive assessment of central and peripheral hemodynamics via impedance cardiography and pulse wave analysis. Participants were classified into tertiles according to the magnitude of PP amplification. Hemodynamic determinants of low PP amplification were explored in univariate and multivariate regression analysis. Results: Compared with the high tertile, patients within the low PP amplification tertile were older and more commonly female and had lower height, weight and heart rate. Augmentation index (AIx) and systemic vascular resistance index (SVRI) were higher among patients within the low PP amplification tertile, whereas aortic pulse wave velocity (PWV) did not differ among groups. In multivariate analysis, higher AIx (OR: 1.27; 95% CI: 1.09–1.48) and higher SVRI were independently associated with higher odds for low PP amplification, whereas higher heart rate was the only parameter related to lower odds for low PP amplification (OR: 0.84; 95% CI: 0.71–0.99). Conclusion: This study shows that among newly-diagnosed drug-naïve hypertensives, elevated wave reflections and systemic vascular resistance are stronger determinants of PP amplification than aortic stiffness. © 2019, © 2019 Taylor &amp; Francis

Effect of hospitalization on 24-h ambulatory blood pressure of hypertensive patients

The aim of this study is to assess the effect of hospital admission on 24-h ambulatory blood pressure (ABP) in hypertensive subjects. Treated or untreated hypertensive adults with open-angle glaucoma underwent inpatient and outpatient 24-h ABP monitoring in a random order 4 weeks apart. Awake ambulatory hours, awake in-bed hours and sleep hours were reported by participants. The nighttime-to-daytime ABP dip (%) and the sleeping-to-awake dip (ambulatory and in-bed) were determined using the two ABP recordings. A total of 40 subjects were analyzed (mean age 65.7±8.4 (s.d.) years, n=19 men). Daytime systolic BP (SBP) was lower in the hospital than in the outpatient setting (mean difference 4.3±10.4 mm Hg, P=0.01), as was the awake ambulatory SBP (mean difference 5.0±11.1 mm Hg, P=0.008). No differences were detected in 24 h, nighttime or sleeping SBP or in any of the respective diastolic outpatient vs. inpatient ABP measurements. The nighttime SBP dip (vs. daytime) was larger in the outpatient setting (8.9±7.5% and 5.2±4.7%, respectively; P=0.003). Sleeping SBP dip (vs. awake ambulatory and awake in-bed) was also larger in the outpatient setting (11.1±7.3 and 7.8±5.9%, respectively; P0.02) with no difference in diastolic ABP. These data suggest that inpatient 24-h ABP monitoring does not reflect the usual BP level during routine daily life, nor does it represent the usual diurnal pattern of an individual. Relying on the 24-h ABP monitoring performed in the hospital environment may lead to an underestimation of ABP and an overdiagnosis of non-dippers. Therefore, 24-h ABP monitoring for decision making regarding diagnosis and treatment of hypertension should be performed only in the routine daily conditions of each individual. © 2010 The Japanese Society of Hypertension All rights reserved

Ambulatory recording of wave reflections and arterial stiffness during intra- and interdialytic periods in patients treated with dialysis

Background and objectives Wave reflections and arterial stiffness are independent cardiovascular risk factors in ESRD. Previous studies in this population included only static recordings before and after dialysis. This study investigated the variation of these indices during intra- and interdialytic intervals and examined demographic, clinical, and hemodynamic variables related to arterial function in patients undergoing hemodialysis. Design, setting, participants, &amp; measurements Between February 2013 and May 2014, a total of 153 patients receiving maintenance hemodialysis in five dialysis centers of northern Greece underwent ambulatory BP monitoringwith the newly introducedMobil-O-Graph device (IEM, Stolberg,Germany) over amidweek dialysis session and the subsequent interdialytic period. Mobil-O-Graph is an oscillometric device that records brachial BP and pulse waves and estimates, via generalized transfer function, aortic BP, augmentation index (AIx) as a measure of wave reflections, and pulse wave velocity (PWV) as an index of arterial stiffness. ResultsAIxwas lower during dialysis than in the interdialytic period of dialysis-on day (Day 1) (mean±6SD, 24.7% 69.7% versus 26.8%69.4%; P&lt;0.001). In contrast, PWV remained unchanged between these intervals (9.31±62.2 versus 9.29±62.3 m/sec; P=0.60). Both AIx and PWV increased during dialysis-off day (Day 2) versus the out-ofdialysis period of Day 1 (28.8%±69.8% versus 26.8%±69.4% [P&lt;0.001] and 9.39±62.3 versus 9.29±62.3 m/sec [P&lt;0.001]). Older age (odds ratio [OR], 1.09; 95%confidence interval [95% CI], 1.02 to 1.15), female sex (OR, 7.56; 95%CI, 1.64 to 34.81), diabetic status (OR, 8.84; 95%CI, 1.76 to 17.48), and higher mean BP (OR, 1.17; 95%CI, 1.09 to 1.27)were associatedwith higher odds of highAIx; higher heart ratewas associatedwith lower odds (OR, 0.71; 95%CI, 0.63 to 0.80) of high AIx. Older age (OR, 2.04; 95%CI, 1.61 to 2.58) and higher mean BP (OR, 1.15; 95%CI, 1.05 to 1.27) were independent correlates of high PWV. Conclusions This study showed a gradual interdialytic increase in AIx, whereas PWV was only slightly elevated during Day 2. Future studies are needed to elucidate the value of these ambulatory measures for cardiovascular risk prediction in ESRD. © 2015 by the American Society of Nephrology

Oral Calcium Supplementation Ambulatory Blood Pressure and Relation to Changes in Intracellular Ions and Sodium-Hydrogen Exchange

BACKGROUND Calcium (Ca2+) supplementation has been shown paradoxically to reduce intracellular Ca2+ and induce vascular relaxation. The aim of the study was to assess 24-h blood pressure (BP) change after Ca2+ supplementation and to investigate its relation to changes in intracellular ions and the activity of the first isoform of sodium-hydrogen exchange (NHE-1) in subjects with hypertension and type 2 diabetes. METHODS This parallel, randomized controlled, single-blinded trial, consisted of 31 patients with type 2 diabetes, and hypertension who were allocated to receive 1,500 mg of Ca2+ per day (n = 15) or no treatment (n = 16) for 8 weeks. RESULTS In the Ca2+ group a decrease of 1.7 +/- 2.7 mm Hg (mean +/- SE) P = 0.52 for mean 24-h systolic BP (SBP) and 2.1 +/- 1.5 mm Hg, P = 0.19 for mean 24-h diastolic BP (DBP) was recorded. Whereas in the control group an increase of 1.4 +/- 2.7 mm Hg, P = 0.59 for mean 24-h SBP and 1.2 +/- 2.8 mm Hg, P = 0.83 for mean 24-h DBP was observed. Intraplatelet Ca2+ decreased whereas intraplatelet magnesium (Mg2+) and erythrocyte K+ increased in the intervention group. Change in mean 24-h SBP in the pooled group correlated with both change in intraplatelet Ca2+ (r = 0.49, P < 0.05) and NHE-1 activity (r = 0.6, P < 0.001). The contribution of intraplatelet Ca2+ was attenuated when both parameters were entered in a multivariate regression model. CONCLUSIONS The present study shows a weak, statistically nonsignificant trend towards association of Ca2+ supplementation on 24-h BP in hypertensive subjects with type 2 diabetes. However, our results indicated an interrelation of [Ca2+], levels and NHE-1 activity on BP in patients with hypertension and type 2 diabetes

Evaluation of a novel brachial cuff-based oscillometric method for estimating central systolic pressure in hemodialysis patients

Background/Aims: Elevated wave reflections and arterial stiffness, as well as ambulatory blood pressure (BP) are independent predictors of cardiovascular risk in end-stage-renaldisease. This study is the first to evaluate in hemodialysis patients the validity of a new ambulatory oscillometric device (Mobil-O-Graph, IEM, Germany), which estimates aortic BP, augmentation index (AIx) and pulse wave velocity (PWV). Methods: Aortic SBP (aSBP), heart rate-adjusted AIx (AIx(75)) and PWV measured with Mobil-O-Graph were compared with the values from the most widely used tonometric device (Sphygmocor, ArtCor, Australia) in 73 hemodialysis patients. Measurements were made in a randomized order after 10 min of rest in the supine position at least 30 min before a dialysis session. Brachial BP (mercury sphygmomanometer) was used for the calibration of Sphygmocor&apos;s waveform. Results: Sphygmocor-derived aSBP and AIx(75) did not differ from the relevant Mobil-O-Graph measurements (aSBP: 136.3 ± 19.6 vs.133.5 ± 19.3 mm Hg, p = 0.068; AIx(75): 28.4 ± 9.3 vs. 30.0 ± 11.8%, p = 0.229). The small difference in aSBP is perhaps explained by a relevant difference in brachial SBP used for calibration (146.9 ± 20.4 vs. 145.2 ± 19.9 mm Hg, p = 0.341). Sphygmocor PWV was higher than Mobil-O-Graph PWV (10.3 ± 3.4 vs. 9.5 ± 2.1 m/s, p &lt; 0.01). All 3 parameters estimated by Mobil-O-Graph showed highly significant (p &lt; 0.001) correlations with the relevant measurements of Sphygmocor (aSBP, r = 0.770; AIx(75), r = 0.400; PWV, r = 0.739). The Bland-Altman Plots for aSBP and AIx(75) showed acceptable agreement between the two devices and no evidence of systemic bias for PWV. Conclusion: As in other populations, acceptable agreement between Mobil-O-Graph and Sphygmocor was evident for aSBP and AIx(75) in hemodialysis patients; PWV was slightly underestimated by Mobil-O-Graph. © 2014 S. Karger AG, Basel

Insulin sensitivity increase after calcium supplementation and change in intraplatelet calcium and sodium-hydrogen exchange in hypertensive patients with Type 2 diabetes

To investigate the effect of oral calcium (Ca2+) supplementation on insulin sensitivity measured by the euglycaemic hyperinsulinaemic clamp, intraplatelet cationic concentration of Ca2+ ([Ca2+](i)) and the transmembrane sodium-hydrogen exchanger (NHE) activity in erythrocytes in subjects with Type 2 diabetes and hypertension. In this parallel randomized controlled single-blinded trial, 31 patients were allocated to receive either 1500 mg of Ca2+ orally, daily (n = 15) or no treatment (n = 16) for 8 weeks. At baseline and at the end of the 8-week period insulin sensitivity, [Ca2+](i) and the first isoform of NHE (NHE-1) activity were measured. At the end of the study, subjects who received Ca2+ supplementation showed higher insulin sensitivity (Delta M-value 0.32 +/- 0.5 mmol/min P < 0.05) and lower [Ca2+](i) (125.0 +/- 24.7 to 80.4 +/- 10.6 nmol/l, P < 0.05, mean +/- sem) and NHE-1 activity (79.5 +/- 10.0 to 52.1 +/- 6.4 mmol Na/l red cell/h, P < 0.05). None of the above parameters were changed in the control group. Simple regression analysis demonstrated the change in [Ca2+](i) significantly determined insulin sensitivity change (beta = -0.36, P < 0.05). Oral Ca2+ supplementation improves insulin sensitivity in patients with Type 2 diabetes and hypertension. These changes are likely to be mediated by changes in intracellular ionic Ca2+. NHE-1 activity was also reduced after Ca2+ supplementation but its role in insulin sensitivity requires further investigation