Prediabetes is associated with abnormal circadian blood pressure variability

Prevalence of prediabetes and associated factors among community members in rural Isingiro district

BACKGROUND

In rural Uganda a significant number of persons afflicted with pre-diabetes are unaware of the condition. This is likely to lead to diabetic complications resulting in catastrophic health expendirure.The burden of prediabetes in rural Isingiro has not previously been determined. This study examined the prevalence of prediabetes and the associated factors among rural community members.

METHODS

We conducted a cross-sectional survey and enrolled 370 participants aged between 18 and 70 years in the Kabuyanda sub-county, rural Isingiro district in march 2021. Multistage sampling and systematic random sampling were conducted to select eligible households. Data was collected using a pretested WHO STEP-wise protocol questionnaire. The primary outcome was prediabetes (FBG = 6.1mmol/l to 6.9mmol/l), calculated as a proportion. Participants known to be diabetic or on medication were excluded. Chi-square tests and multivariate logistic regression model were performed for data analysis using STATA.

RESULTS

The prevalence of prediabetes was 9.19% (95% CI 6.23-12.14). Independent factors significantly associated with pre-diabetes were; advancing age [AOR = 5.7, 95% CI:1.03-32.30], moderate-intensity work [AOR = 2.6,95% CI:1.23-5.63], high level of consumption of a healthy diet [AOR = 5.7, 95% CI:1.67-19.05] and body mass index [AOR = 3.7, 95% CI:1.41-9.20].

CONCLUSION

Prediabetes is prevalent among adult community members in rural Isingiro, southwestern Uganda. Age and lifestyle factors predict prediabetes in this rural population, suggesting a need for targeted health promotion interventions.

Prediabetes, Non-Dipping Profile and Hypertension—A Recipe for Increased Arterial Stiffness

Background: Pulse wave velocity (PWV) is a known predictor of target organ damage, cardiovascular disease and overall mortality. The aim of this study was to compare the PWV values in subjects with prediabetes, a non-dipper profile and arterial hypertension with their values in healthy subjects. Methods: A total of 301 subjects, aged 40–70 years, without diabetes mellitus were included in this cross-sectional study (150 with prediabetes). They underwent a 24 h ambulatory blood pressure monitoring (ABPM). Subjects were divided into three hypertension groups (A = healthy, B = controlled hypertension, C = uncontrolled hypertension). Dipping status was determined according to ABPM results, and PWV was measured by an oscillometric device. Prediabetes was defined as having 2 separate fasting plasma glucose (FPG) measurements between 5.6 and 6.9 mmol/L. Results: The highest PWV values were found in group C (9.60 ± 1.34 vs. 8.46 ± 1.01 in group B vs. 7.79 ± 1.10 in group A; p < 0.001), in subjects with prediabetes (8.98 ± 1.31 m/s vs. 8.26 ± 1.22 m/s; p < 0.001) and in prediabetic non-dippers among age groups (p = 0.05). In the multivariate regression model age, blood pressure, nocturnal indices and FPG were shown as independent predictors of PWV values. Conclusion: Significantly higher PWV values were found in subjects with prediabetes and non-dipping profiles in all three examined hypertension groups.

Prognostic value of ambulatory blood pressure values in elderly patients with heart failure. Results of the DICUMAP study

INTRODUCTION

Ambulatory blood pressure monitoring (ABPM) has demonstrated value in the prognostic assessment of hypertensive patients with heart failure (HF) with or without other cardiovascular diseases. The objective of this study was to evaluate whether ABPM can identify subjects with HF with a worse prognosis.

METHODS AND RESULTS

Prospective multicenter study that included clinically stable outpatients with HF. All patients underwent ABPM. A total of 154 patients from 17 centers were included. Their mean age was 76.8 years (± 8.3) and 55.2% were female. In total, 23.7% had HF with a reduced ejection fraction (HFrEF), 68.2% were in NYHA functional class II, and 19.5% were in NYHA functional class III. At one year of follow up, there were 13 (8.4%) deaths, of which 10 were attributed to HF. Twenty-nine patients required hospitalization, of which 19 were due to HF. The presence of a non-dipper BP pattern was associated with an increased risk for readmission or death at one year of follow-up (25% vs. 5%; p=.024). According to a Cox regression analysis, more advanced NYHA functional class (hazard ratio 3.51; 95% CI 1.70-7.26; p=.001; for NYHA class III vs. II) and a higher proportional nocturnal reduction in diastolic BP (hazard ratio 0.961; 95%CI 0.926-0.997; p=.032 per 1% diastolic BP reduction) were independently associated with death or readmission at one year.

CONCLUSION

In older patients with chronic HF, a non-dipper BP pattern measured by ABPM was associated with a higher risk of hospitalization and death due to HF.

Cardiac magnetic resonance assessment of aortic distensibility in prediabetic patients

Background

Hyperglycemia, insulin resistance, and hyperinsulinemia represent important pathophysiological components of the prediabetic stage that result in arteriosclerosis and increased arterial stiffness. We sought to compare the aortic distensibility (AD) assessed by cardiac magnetic resonance (CMR) in prediabetic patients presenting with chronic coronary artery disease (CCAD) versus patients with normal HbA1C. Ninety-eight patients with CCAD were recruited. All patients were screened for HbA1C levels and then underwent a CMR study to assess AD of the aortic root and the ascending and descending thoracic aorta. Patients were classified into two groups: 52 prediabetic (HbA1C 5.7–6.4%) (study group) and 46 with normal glycemic status (HbA1C < 5.7%) (control group).

Results

AD values at the aortic root (AR) (13.93 ± 5.17 vs 34.3 ± 9.65 Kpa^-1 × 10^-3), ascending aorta (AA) (13.17 ± 4.81 vs 28.1 ± 8.33 Kpa^-1 × 10^-3), and descending thoracic aorta (DA) (18.12 ± 4.34 vs 33.68 ± 7.57 Kpa^-1 × 10^-3) were significantly lower in the study group than in the control group (P value for all was < 0.001). Twenty-eight patients fulfilled the criteria for metabolic syndrome, and in those patients, AD was significantly lower than in those without metabolic syndrome.

Aortic distensibility at the AR, AA, and DA had strong significant negative correlations with the level of glycosylated hemoglobin (AA, AR, DA; r − 0.66, − 0.68, − 0.58, respectively) (P < 0.001).

Conclusion

AD values at different points (AR, AA, and DA) were significantly lower in prediabetic and metabolic syndrome patients than in controls. These values also showed a significant negative correlation with the levels of HBA1C.

Association between blood pressure variability, cardiovascular disease and mortality in type 2 diabetes: A systematic review and meta-analysis

AIM

To investigate the associations of blood pressure variability (BPV), expressed as long-term (visit-to-visit) and short-term (ambulatory blood pressure monitoring [ABPM] and home blood pressure monitoring [HBPM]) and all-cause mortality, major adverse cardiovascular events (MACEs), extended MACEs, microvascular complications (MiCs) and hypertension-mediated organ damage (HMOD) in adult patients with type 2 diabetes.

MATERIALS AND METHODS

PubMed, Medline, Embase, Cinahl, Web of Science, ClinicalTrials.gov and grey literature databases were searched for studies including patients with type 2 diabetes, at least one variable of BPV (visit-to-visit, HBPM, ABPM) and evaluation of the incidence of at least one of the following outcomes: all-cause mortality, MACEs, extended MACEs and/or MiCs and/or HMOD. The extracted information was analyzed using random effects meta-analysis and meta-regression.

RESULTS

Data from a total of 377 305 patients were analyzed. Systolic blood pressure (SBP) variability was associated with a significantly increased risk of all-cause mortality (HR 1.12, 95% CI 1.04-1.21), MACEs (HR 1.01, 95% CI 1.04-1.17), extended MACEs (HR 1.07, 95% CI 1.03-1.11) and MiCs (HR 1. 12, 95% CI 1.01-1.24), while diastolic blood pressure was not. Associations were mainly driven from studies on long-term SBP variability. Qualitative analysis showed that BPV was associated with the presence of HMOD expressed as carotid intima-media thickness, pulse wave velocity and left ventricular hypertrophy. Results were independent of mean blood pressure, glycaemic control and serum creatinine levels.

CONCLUSIONS

Our results suggest that BPV might provide additional information rather than mean blood pressure on the risk of cardiovascular disease in patients with type 2 diabetes.

Disrupted circadian rhythms of body temperature, heart rate and fasting blood glucose in prediabetes and type 2 diabetes mellitus

We report a progressive disruption of 24-h rhythms in fasting blood glucose (FBG), body temperature (BT) and heart rate (HR) associated with metabolic dysfunction and the development of prediabetes (PD) and type 2 diabetes mellitus (T2DM) in overweight middle-aged (40-69 years old) humans. Increasing BT and HR mean values and declining 24-h BT and HR amplitudes accompany adverse changes in metabolic state. Increased nocturnal BT and a phase delay of the 24-h BT rhythm, deviant 24-h HR profile and a phase advance of the 24-h HR and FBG rhythms are early signs of the PD metabolic state. In T2DM, the 24-h FBG rhythm is no longer detectable, and the 24-h amplitudes of BT and HR are greatly diminished. In addition, lepton and creatinine values were lowered in T2DM. Moreover, positive correlations between FBG and body mass index, BMI, and negative correlations between the 24-h amplitude of FBG and BMI indicate that overweight is an additional factor causing disruption of the circadian rhythms. Further studies on circadian disruption as a consequence of metabolic dysfunction are necessary. The quantitative analysis of changing circadian BT and HR rhythms may provide prognostic markers of T2DM and therapeutic targets for its prevention and correction.

Different Combinations of Glucose Tolerance and Blood Pressure Status and Incident Diabetes, Hypertension, and Chronic Kidney Disease

Background

The impact of different combinations of glucose tolerance and blood pressure status on the development of type 2 diabetes mellitus (T2DM), hypertension (HTN), and chronic kidney disease (CKD) still needs to be investigated.

Methods and Results

A total of 12 808 Iranian adults aged ≥20 years were included in 3 separate analyses to investigate incidence of T2DM, HTN, and CKD. Multivariate Cox proportional hazard models were used to calculate hazard ratios (95% CI). During a median follow‐up of >10 years, the overall incidence rate for T2DM, HTN, and CKD was 12.2, 29.8, and 24.8 per 1000 person‐years. For incident T2DM, considering normal glucose tolerance/normal blood pressure as reference, prediabetes (PreDM)/HTN had the highest risk (hazard ratio: 7.22 [5.71–9.12]) while PreDM/normal blood pressure also showed a significant risk (5.58 [4.41–7.05]). Furthermore, risk of PreDM/HTN was higher than PreDM/normal blood pressure (P<0.05). For incident HTN, normal glucose tolerance/prehypertension was a strong predictor (3.28 [2.91–3.69]); however, addition of PreDM or T2DM did not increase the risk. For incident CKD, every category that included HTN and/or T2DM showed significant risk; this risk was marginally significant for the PreDM/HTN group (1.19 [0.98–1.43], P=0.06). In addition, PreDM/ normal blood pressure was a marginally significant risk factor for incident HTN while normal glucose tolerance/prehypertension was a significant predictor of T2DM.

Conclusions

Presence of HTN was associated with increased risk of T2DM among the PreDM population; however, dysglycemia did not increase the risk of HTN among individuals with prehypertension. For incident CKD, intensive management of HTN and T2DM, rather than their predisease states, should be considered.

Nighttime BP in Elderly Individuals with Prediabetes/Diabetes with and without CKD: The HEIJO-KYO Study

BACKGROUND

and objectives Although previous studies suggested that nighttime BP is elevated in diabetes mellitus, the association between prediabetes and nighttime BP remains unclear. In addition, the relationship between diabetic status, renal function, and nighttime BP has not been evaluated in large populations.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

In this cross-sectional study, we assessed diabetic status, renal function, and ambulatory BP parameters among 1081 community-dwelling elderly individuals (mean age, 71.8±7.0 years). Participants were classified into six categories based on diabetic status (normoglycemia, prediabetes, or diabetes mellitus) and renal function (normal function or CKD). BP was measured at 30-minute intervals for 48 hours using a validated ambulatory recorder.

RESULTS

The mean nighttime systolic BP (SBP) was 115.7±16.1 mmHg. The multivariable analysis, adjusted for age, sex, smoking status, and daytime SBP, revealed that, compared with participants with normoglycemia but without CKD (n=378), mean nighttime SBP was significantly higher in participants with both prediabetes and CKD (n=93) by 2.9 mmHg (95% confidence interval [95% CI], 0.2 to 5.6; P=0.03) and in patients with both diabetes mellitus and CKD (n=30) by 7.8 mmHg (95% CI, 3.5 to 12.2; P<0.001) but not in participants with both normoglycemia and CKD (n=75), participants with prediabetes without CKD (n=374), or patients with diabetes mellitus without CKD (n=131). Notably, the multivariable analysis indicated that the interaction terms of diabetic status and renal function were significantly associated with nighttime SBP (P=0.03).

CONCLUSIONS

Nighttime SBP was significantly higher in participants with prediabetes and CKD but not in participants with prediabetes without CKD, compared with participants with normoglycemia and without CKD. In addition, a significant interaction effect of diabetic status and renal function on nighttime SBP was detected in a general elderly population.

The Association Between Pre-Diabetes With Body Mass Index and Marital Status in an Iranian Urban Population

Pre-diabetes increased the development of diabetes mellitus (type 2). The aim of study was to determine the association of body weight, education and marital status with pre-diabetes in an Iranian urban population.A sample of 788 subjects (360 men and 428 women) between the ages 30-85 years participated in our study and anthropometric measurements, educational level and fasting blood sugar of participants were recorded. The t and Chi square tests were used for continuous and categorical variables. The association of age, BMI categories, educational level and marital status to pre-diabetes was assessed by estimating the odds ratio. A p-value ≤ 0.05 were considered significant. The analysis was done using SPSS version 11.5. Our study showed that pre-diabetic subjects were older and low educated than normoglycemic subjects. Mean BMI and educational level were associated to pre-diabetes only in women. The odds of being pre-diabetes also were higher in obese women than in normal BMI women. No relationship was found between education and marital status with pre-diabetes in both men and women. Based on our finding, it is possible that advancing age and obesity has increased in pre-diabetes. This highlights the importance of population based survey to monitor blood glucose for effective prevention and control.

Blueberries improve endothelial function, but not blood pressure, in adults with metabolic syndrome: a randomized, double-blind, placebo-controlled clinical trial

Blueberry consumption has been shown to have various health benefits in humans. However, little is known about the effect of blueberry consumption on blood pressure, endothelial function and insulin sensitivity in humans. The present study investigated the role of blueberry consumption on modifying blood pressure in subjects with metabolic syndrome. In addition, endothelial function and insulin sensitivity (secondary measurements) were also assessed. A double-blind and placebo-controlled study was conducted in 44 adults (blueberry, n = 23; and placebo, n = 21). They were randomized to receive a blueberry or placebo smoothie twice daily for six weeks. Twenty-four-hour ambulatory blood pressure, endothelial function and insulin sensitivity were assessed pre- and post-intervention. The blood pressure and insulin sensitivity did not differ between the blueberry and placebo groups. However, the mean change in resting endothelial function, expressed as reactive hyperemia index (RHI), was improved significantly more in the group consuming the blueberries versus the placebo group (p = 0.024). Even after adjusting for confounding factors, i.e., the percent body fat and gender, the blueberry group still had a greater improvement in endothelial function when compared to their counterpart (RHI; 0.32 ± 0.13 versus −0.33 ± 0.14; p = 0.0023). In conclusion, daily dietary consumption of blueberries did not improve blood pressure, but improved (i.e., increased) endothelial function over six weeks in subjects with metabolic syndrome.

Prediabetes and associated disorders

Prediabetes represents an elevation of plasma glucose above the normal range but below that of clinical diabetes. Prediabetes includes individuals with IFG, IGT, IFG with IGT and elevated HbA1c levels. Insulin resistance and β-cell dysfunction are characteristic of this disorder. The diagnosis of prediabetesis is vital as both IFG and IGT are indeed well-known risk factors for type 2 diabetes with a greater risk in the presence of combined IFG and IGT. Furthermore, as will be illustrated in this review, prediabetes is associated with associated disorders typically only considered in with established diabetes. These include cardiovascular disease, periodontal disease, cognitive dysfunction, microvascular disease, blood pressure abnormalities, obstructive sleep apnea, low testosterone, metabolic syndrome, various biomarkers, fatty liver disease, and cancer. As the vast majority of individuals with prediabetes are unaware of their diagnosis, it is therefore vital that the associated conditions are identified, particularly in the presence of mild hyperglycemia, so they may benefit from early intervention.

Within-visit blood pressure variability is associated with prediabetes and diabetes

We investigated the associations between within-visit blood pressure variability (BPV) and risk factors for cardiovascular disease (CVD). The study subjects included 17,795 people aged 40–74 years who underwent health check-ups in Aichi Prefecture, Japan, and completed two blood pressure measurements. Subjects were categorized into three groups according to the difference of systolic blood pressure (ΔSBP), namely, low-BPV (≤10 mmHg), moderate-BPV (11–20 mmHg), and high-BPV (>20 mmHg). Subjects were also divided into three categories as those without prediabetes (glycosylated hemoglobin A_1c [HbA_1c] < 5.7%), prediabetes (HbA_1c 5.7–6.4%) and diabetes (HbA_1c ≥ 6.5% or under treatment for diabetes). The proportion of prediabetes and diabetes were significantly higher in subjects with high-BPV than in those with low-BPV after adjusting for age, sex, and mean SBP (odds ratio [95% confidence interval] was 1.16 [1.01–1.33] for prediabetes and 1.33 [1.06–1.66] for diabetes). Other CVD risk factors were not associated with high-BPV after the adjustment. In conclusion, increased within-visit BPV was significantly associated with the prevalence of prediabetes and diabetes, independent of mean SBP, in a large general population. Therefore, assessing BPV in a single visit may help to identify subjects at increased risk of impaired glycemic control.

Identification of insulin as a novel retinoic acid receptor-related orphan receptor α target gene

Insulin plays an important role in regulation of lipid and glucose metabolism. Retinoic acid receptor-related orphan receptor α (RORα) modulates physiopathological processes such as dyslipidemia and diabetes. In this study, we found overexpression of RORα in INS1 cells resulted in increased expression and secretion of insulin. Suppression of endogenous RORα caused a decrease of insulin expression. Luciferase and electrophoretic mobility shift assay (EMSA) assays demonstrated that RORα activated insulin transcription via direct binding to its promoter. RORα was also observed to regulate BETA2 expression, which is one of the insulin active transfactors. In vivo analyses showed that the insulin transcription is increased by the synthetic RORα agonist SR1078. These findings identify RORα as a transcriptional activator of insulin and suggest novel therapeutic opportunities for management of the disease.

Chronobiologically Interpreted Ambulatory Blood Pressure Monitoring in Health and Disease

To detect vascular variability anomalies (VVAs), a blood pressure and heart rate profile around the clock for at least 7 days is a start. As a minimum, measurement every 60 or preferably 30 minutes for a week is needed, to be continued if abnormality is found, to assess the about 24-hour (circadian) variability that exists in all individuals. As a first dividend, one then also obtains a glimpse of 2 of the very many longer-than-circadian periodicities, the biological half-week and week. Certainly if we can have sensors and computer chips in our cars that continuously monitor the pressure over a tire's life, we should be able to do the same job for ourselves for diagnostic and therapeutic decisions. Healthcare today emphasizes wellness with recommendations for exercise and a proper diet, yet these evaluations may not be adequate. BP may be measured at a visit to the doctor or before an exercise session, along with measuring body weight and performing a physical exam. The seeds of disease are planted long before they are visible, and what appears to be normal from a conventional point of view may in fact actually be abnormal. Hidden alterations of physiological function, masked by the body's remarkable adaptive capabilities, may become visible through a new diagnostic and therapeutic realm-chronobiology-that reveals hitherto unseen abnormalities. The tools of chronobiology may yield additional dividends, such as the detection of physiological "loads" related to stress and stress relief and the undesirable effcts of space weather upon personal events such as sudden cardiac death, societal events like terrorism and war, and natural disasters. Chronobiologi cally interpreted automatic ambulatory BP and heart rate (HR) monitoring (C-ABPM) may detect the antecedents of these types of events. C-ABPM is of interest in preventive cardiology, since it reveals new diagnoses as vascular variability anomalies (VVAs) and renders previous conventional diagnoses more reliable, such as that of an elevated BP. These VVAs include MESOR (midline-estimating statistic of rhythm)-hypertension, an elevation of the MESOR, which is diagnosed, like all other VVAs, only after I or preferably several replications of 7-day around-the-clock BP monitoring with available, affordable, and unobtrusive instrumentation. The recommendation for continuous C-ABPM recognizes several principles that constitute inseparably intertwined contributors to severe cardio-, cerebro- and renovascular diease. C-ABPM gauges wear and tear of genetics, physical loads, and in particular mental stress placed upon individuals from "womb to tomb" by daily life, including weather in extraterrestrial space as well as that on earth, as a continuous surveillance paradigm preventing us from flying blind to a change from less than 5% to near 100% in the risk of a stroke within 6 years.

Diagnosing vascular variability anomalies, not only MESOR-hypertension

Chronobiology is the study of biological rhythms. Chronomics investigates interactions with environmental cycles in a genetically coded autoresonance of the biosphere with wrangling space and terrestrial weather. Analytical global and local methods applied to human blood pressure records of around-the-clock measurements covering decades detect physiological-physical interactions, a small yet measurable response to solar and terrestrial magnetism. The chronobiological and chronomic interpretation of ambulatory blood pressure monitoring (C-ABPM) records in the light of time-specified reference values derived from healthy peers matched by sex and age identify vascular variability anomalies (VVAs) for an assessment of cardio-, cerebro-, and renovascular disease risk. Even within the conventionally accepted normal range, VVAs have been associated with a statistically significant increase in risk. Long-term C-ABPM records help to "know ourselves," serving for relief of psychological and other strain once transient VVAs are linked to the source of a load, prompting adjustment of one's lifestyle for strain reduction. Persistent circadian VVAs can be treated, sometimes by no more than a change in timing of the daily administration of antihypertensive medication. Circadian VVA assessment is an emergency worldwide, prompted in the United States by 1,000 deaths per day every day from problems related to blood pressure. While some heads of state met under United Nation and World Health Organization sponsorship to declare that noncommunicable diseases are a slow-motion disaster, a resolution has been drafted to propose C-ABPM as an added tool complementing purely physical environmental monitoring to contribute also to the understanding of social and natural as well as personal cataclysms.

Toward a personalized chronotherapy of high blood pressure and a circadian overswing

Timing can greatly affect the response to a stimulus, including antihypertensive medications. Herein, we assess the response of 30 patients to losartan/hydrochlorothiazide (L/H), administered for at least 1 month at a given circadian stage to each patient, this stage being changed during consecutive spans to cover six treatment times from awakening to bedtime at approximately 3-hour intervals. At the end of each stage, each patient underwent a 7-day around-the-clock ambulatory blood pressure (BP) profile, analyzed chronobiologically. A larger reduction of the midline estimating statistic of rhythm (MESOR; a rhythm-adjusted mean) of diastolic BP was achieved by L/H administration in the early morning for more patients (P < .05), while treatment upon awakening was the best choice for most patients to reduce the circadian amplitude of BP the most (P < .01). The optimal treatment time varied considerably among patients, however. Special attention should be given to the effect on the circadian amplitude since treatment can increase it above a threshold, beyond which there is a marked increase in cardiovascular disease risk. The results indicate the desirability to individualize the optimization of the antihypertensive effect of L/H by timing along the circadian scale.

Autonomic dysfunction and circadian blood pressure variations in people with impaired glucose tolerance

AIMS

To assess circadian blood pressure variability in people with impaired glucose tolerance and a healthy control population.

METHODS

Seventy-five people with impaired glucose tolerance and 40 healthy volunteers (frequency matched on 10-year age bands and sex) underwent a detailed neurological assessment. Autonomic neuropathy was detected by the five standard cardiovascular autonomic tests and heart rate variability was characterized by the triangle index. Diurnal indices were assessed by 24-h ambulatory blood pressure monitoring. Systolic and diastolic diurnal indices were defined as: (mean daytime blood pressure - mean night-time blood pressure) × 100/mean daytime blood pressure.

RESULTS

Mean 24-h systolic and diastolic blood pressure was significantly higher in the group with impaired glucose tolerance compared with the control group [126 ± 12 (mean ± SD) vs. 117 ± 10, 75 ± 7 vs. 71 ± 6 mmHg, both P < 0.05). Systolic and diastolic diurnal indices and heart rate variability triangular index were significantly lower in people with impaired glucose tolerance compared with control subjects (9.1 ± 7.8 vs. 13.2 ± 5.4, 14.5 ± 9.7 vs. 18.4 ± 7.1 mmHg, 28.0 ± 8.4 vs. 39.5 ± 9.3, all P < 0.05). Differences in mean diastolic blood pressure, heart rate variability triangular index and the frequency of non-dippers between those with impaired glucose tolerance and control subjects seemed to be independent of BMI and the presence of cardiovascular autonomic neuropathy, as simultaneous adjustment for BMI and cardiovascular autonomic neuropathy had no major effect on the results.

CONCLUSION

Our data suggest that people with impaired glucose tolerance have increased diastolic blood pressure and abnormal circadian blood pressure regulation, independent of obesity and the presence of cardiovascular autonomic neuropathy.

Cardiovascular risk escalation with caloric excess: a prospective demonstration of the mechanics in healthy adults

CONTEXT

The link between weight gain and cardiovascular risk characterized with circadian blood pressure variability [CBPV] and endothelial function [EF] is unexplored.

OBJECTIVE

To prospectively demonstrate weight gain in healthy adults, increases body fat [BF], enlarges waist circumference [WC], expands visceral adipose tissue [VAT], exacerbates systemic inflammation [sIF], worsens insulin resistance [IR] and enhances functional cardiovascular disease [CVD] risk.

DESIGN, SETTING AND PARTICIPANTS

Healthy men [n=11] and women [n=3] provided initial and eight-week post-caloric excess anthropometric and fasting laboratory measures. Functional CVD risk assessments: CBPV and resting EF were also obtained with 7-day automatic ambulatory BP monitoring and increased test finger peripheral arterial tone [PAT] relative to control [reported as relative hyperemia index (RHI)], respectively.

INTERVENTION

After determining individualized mean energy requirements for weight maintenance over 7-days, each participant received a personalized over feeding prescription (1.4 times; 41% carbohydrate, 44% fat, and 15% protein) for 8-weeks.

RESULTS

mean (SEM). Participants increased body weight [BW; +7.4(0.1) kg]*, body mass index [BMI; +2.5(0.2) kg/m²]*, BF [+2.0(0.01)%]*, WC [+8.2(1.0) cm]*, and VAT [+0.2(0.03) L]* and intrahepatic lipid [IHL + 0.0004(0.002) L] :*all p < 0.01. Increased subcutaneous adipose cell size [+0.3(0.01) ρL; p = 0.02] accompanied significant sIF [hs-CRP + 0.4(0.09) mg/dL; p = 0.04; leptin 6.63 ng/ml; p = 0.0008] and IR [fasting plasma glucose; [FPG] +7.0(0.6) mg/dL;p = 0.01, fasting insulin; [FI] +5.7(1.4) uIU/ml; p = 0.001, HOMA-IR +1.6(0.5); p = 0.02]. Abn CBPV {systolic [+5.4(0.8); p = 0.002, diastolic [+1.7(0.1); p = 0.07 and pulse pressure [PP] [+3.5(0.4); p = 0.003 mm Hg} or elevated heart rate [HR] [+4.9(0.5) bpm; p = 0.003] ensued. Resting RHI declined by 0.47(0.004) from initial 2.24(0.09) to 1.77(0.1); p = 0.001, indicating endothelial dysfunction [ED].

CONCLUSIONS

Controlled caloric excess in healthy human adults over only 8-weeks significantly increased BF, VAT, sIF [hs-CRP], IR [FPG, FI, HOMA-IR] and functional CVD risk [measured as abnormal circadian blood pressure variability and impaired resting endothelial function].

Endothelial Dysfunction: An Early Cardiovascular Risk Marker in Asymptomatic Obese Individuals with Prediabetes

AIMS: To elucidate if endothelial dysfunction is an early CV risk marker in obese men and women with prediabetes. STUDY DESIGN: Cross-sectional study. PLACE AND DURATION OF STUDY: Clinical Research Unit, Pennington Biomedical Research Center, Baton Rouge, LA. United States. METHODOLOGY: Overweight and obese status denotes an increasing adipose tissue burden which spills over into ectopic locations, including the visceral compartment, muscle and liver. Associated co-morbidities enhance cardiovascular (CV) risk. Endothelium which is the largest receptor-effector end-organ in our bodies, while responding to numerous physical and chemical stimuli maintains vascular homeostasis. Endothelial dysfunction (ED) is the initial perturbation, which precedes fatty streak known to initiate atherosclerosis: insidious process which often culminates as sudden catastrophic CV adverse event. Asymptomatic men and women; [n=42] coming in after an overnight fast had demographic, anthropometric, clinical chemistry and resting endothelial function [EF: increased test finger peripheral arterial tone (PAT) relative to control; expressed as relative hyperemia index (RHI)] assessments. RESULTS: Adults with desirable weight [n=12] and overweight [n=8] state, had normal fasting plasma glucose [Mean(SD)]: FPG [91.1(4.5), 94.8(5.8) mg/dL], insulin [INS, 2.3(4.4), 3.1(4.8) μU/ml], insulin sensitivity by homeostasis model assessment [HOMA-IR, 0.62(1.2), 0.80(1.2)] and desirable resting clinic blood pressure [SBP/DBP, 118(12)/74(5), 118(13)/76(8) mmHg]. Obese adults [n=22] had prediabetes [FPG, 106.5(3.5) mg/dL], hyperinsulinemia [INS 18.0(5.2) μU/ml], insulin resistance [HOMA-IR 4.59(2.3)], prehypertension [PreHTN; SBP/DBP 127(13)/81(7) mmHg] and endothelial dysfunction [ED; reduced RHI 1.7(0.3) vs. 2.4(0.3); all p<0.05]. Age-adjusted RHI correlated with BMI [r=-0.53; p<0.001]; however, BMI-adjusted RHI was not correlated with age [r=-0.01; p=0.89]. CONCLUSION: Endothelial dysfunction reflective of cardiometabolic changes in obese adults can be an early risk marker for catastrophic CV events.

Dysglycemia induces abnormal circadian blood pressure variability

BACKGROUND

Prediabetes (PreDM) in asymptomatic adults is associated with abnormal circadian blood pressure variability (abnormal CBPV).

HYPOTHESIS

Systemic inflammation and glycemia influence circadian blood pressure variability.

METHODS

Dahl salt-sensitive (S) rats (n = 19) after weaning were fed either an American (AD) or a standard (SD) diet. The AD (high-glycemic-index, high-fat) simulated customary human diet, provided daily overabundant calories which over time lead to body weight gain. The SD (low-glycemic-index, low-fat) mirrored desirable balanced human diet for maintaining body weight. Body weight and serum concentrations for fasting glucose (FG), adipokines (leptin and adiponectin), and proinflammatory cytokines [monocyte chemoattractant protein-1 (MCP-1) and tumor necrosis factor-α (TNF-α)] were measured. Rats were surgically implanted with C40 transmitters and blood pressure (BP-both systolic; SBP and diastolic; DBP) and heart rate (HR) were recorded by telemetry every 5 minutes during both sleep (day) and active (night) periods. Pulse pressure (PP) was calculated (PP = SBP-DBP).

RESULTS

[mean(SEM)]: The AD fed group displayed significant increase in body weight (after 90 days; p < 0.01). Fasting glucose, adipokine (leptin and adiponectin) concentrations significantly increased (at 90 and 172 days; all p < 0.05), along with a trend for increased concentrations of systemic pro-inflammatory cytokines (MCP-1 and TNF-α) on day 90. The AD fed group, with significantly higher FG, also exhibited significantly elevated circadian (24-hour) overall mean SBP, DBP, PP and HR (all p < 0.05).

CONCLUSION

These data validate our stated hypothesis that systemic inflammation and glycemia influence circadian blood pressure variability. This study, for the first time, demonstrates a cause and effect relationship between caloric excess, enhanced systemic inflammation, dysglycemia, loss of blood pressure control and abnormal CBPV. Our results provide the fundamental basis for examining the relationship between dysglycemia and perturbation of the underlying mechanisms (adipose tissue dysfunction induced local and systemic inflammation, insulin resistance and alteration of adipose tissue precursors for the renin-aldosterone-angiotensin system) which generate abnormal CBPV.

Circadian rhythms in adipose tissue: an update

PURPOSE OF REVIEW

Over the past decade, evidence has accumulated from basic science, clinical and epidemiological studies linking circadian mechanisms to adipose tissue biology and its related comorbidities, diabetes, metabolic syndrome and obesity. This review highlights recent in-vitro and in-vivo findings from murine, human and model organism studies.

RECENT FINDINGS

High-fat diets attenuate circadian mechanisms in murine adipose depots and these effects appear to be due to obesity rather than hyperglycemia. Deletion of circadian regulatory genes such as AMPK1 and nocturnin alter the circadian biology of adipose tissue. Unlike the mouse, circadian gene oscillation in human adipose tissue appears to be independent of BMI and diabetes status, suggesting that circadian mechanistic variation occurs across species. Clues for future directions in this emerging field come from studies of the hibernation and torpor state in mammals and infection models involving the Drosophila metabolic organ or 'fat body'.

SUMMARY

There is a growing consensus that circadian rhythms and metabolism are tightly regulated in adipose tissue and peripheral metabolic organs. Although central mechanisms are critical, autonomous clocks exist within the adipocytes themselves. Future circadian advances are likely to result from the studies of adipose tissue-specific gene deletions.

Circadian blood pressure variability in type 1 diabetes subjects and their nondiabetic siblings - influence of erythrocyte electron transfer

BACKGROUND

Normotensive non-diabetic relatives of type 1 diabetes (T1D) patients have an abnormal blood pressure response to exercise testing that is associated with indices of metabolic syndrome and increased oxidative stress. The primary aim of this study was to investigate the circadian variability of blood pressure and the ambulatory arterial stiffness index (AASI) in healthy siblings of T1D patients vs healthy control subjects who had no first-degree relative with T1D. Secondary aims of the study were to explore the influence of both cardiovascular autonomic function and erythrocyte electron transfer activity as oxidative marker on the ambulatory blood pressure profile.

METHODS

Twenty-four hour ambulatory blood pressure monitoring (ABPM) was undertaken in 25 controls, 20 T1D patients and 20 siblings. In addition to laboratory examination (including homeostasis model assessment of insulin sensitivity) and clinical testing of autonomic function, we measured the rate of oxidant-induced erythrocyte electron transfer to extracellular ferricyanide (RBC vfcy).

RESULTS

Systolic blood pressure (SBP) midline-estimating statistic of rhythm and pulse pressure were higher in T1D patients and correlated positively with diabetes duration and RBC vfcy; autonomic dysfunction was associated with diastolic BP ecphasia and increased AASI. Siblings had higher BMI, lower insulin sensitivity, larger SBP amplitude, and higher AASI than controls. Daytime SBP was positively, independently associated with BMI and RBC vfcy. Among non-diabetic people, there was a significant correlation between AASI and fasting plasma glucose.

CONCLUSIONS

Siblings of T1D patients exhibited a cluster of sub-clinical metabolic abnormalities associated with consensual perturbations in BP variability. Moreover, our findings support, in a clinical setting, the proposed role of transplasma membrane electron transport systems in vascular pathobiology.

Abnormalities in circadian blood pressure variability and endothelial function: pragmatic markers for adverse cardiometabolic profiles in asymptomatic obese adults

Background

Cardiovascular disease (CVD) risk, although perceived to be high, is often difficult to demonstrate in disease free (healthy) obese adults.

Hypothesis

Changes in circadian blood pressure variability (CBPV) and endothelial function (EF) may be early correlates of cardiometabolic disorders.

Methods

Asymptomatic men and women in 3 groups: normal weight (n = 10), overweight (n = 10) and obese (n = 15) were evaluated. Blood pressure and heart rate were recorded over 7 days: every 30 minutes during the day and every 60 minutes during the night, by automatic ambulatory monitoring. Resting EF was assessed in a fasting state between 8-10 AM by brachial ultrasound. Anthropometric and cardiometabolic indicators were measured and correlations with CBPV and EF were investigated.

Results

The 3 groups had (Mean(SD)) BMI: 22.6(1.6), 27(3) and 34(5) kg/m², respectively, weight: 64(16), 79(14), 95(16) kg and waist circumference: 79(9), 93(10), 107(13) cm. None in normal-weight or overweight groups had abnormal CBPV, while 8 of 15 obese adults had one or more CBPV abnormities (p < 0.05). Obese adults with CBPV abnormalities had elevated hs-CRP (15.3(9.3) mg/L), fibrinogen (593(97) mg/dl), fasting serum glucose (102(16) mg/dL), and cardiac risk ratios (Total-C/HDL-C: 5.2(1.9), LDL-C/HDL-C: 3.1(1.4)). Adults in the 3 respective groups who did not have CBPV abnormalities had flow-mediated brachial artery dilatation (FMD) of 0.22(0.06); 0.20(0.04), 0.23(0.02) mm over resting diameter. Obese participants with CBPV abnormalities (Mesor-hypotension, circadian hyper amplitude tension, elevated pulse pressure), had attenuated FMD at 78, 52, and 56% of resting reference diameter (means 0.18(0.07), 0.12(0.08), and 0.13(0.05) mm; p < 0.05), respectively.

Conclusions

Asymptomatic obese adults with abnormal CBPV and EF exhibit unfavorable cardiometabolic profiles.

Prehypertension in disease-free adults: a marker for an adverse cardiometabolic risk profile

Cardiovascular disease (CVD) is the leading cause of death worldwide. Understandably, cardiometabolic risk assessment is an integral component of every adult health evaluation. Customary assessment measures are, however, inadequate: as two-thirds of sudden cardiac deaths occur in clinically healthy individuals. Novel indicators favoring early recognition of adverse cardiometabolic risk in disease-free adults are clearly needed. Clinically healthy disease-free adults with prehypertension (PreHTN: BP120-139/80-89 mm Hg) have an adverse cardiometabolic risk profile. A statistical analysis of disease-free adult NHANES participants was conducted from 1999 to 2006. Overall prevalence of PreHTN in disease-free adults was 36.3%. Prevalence was higher in men (P<0.001) increasing with age up to 70 years (P<0.001). Prevalence correlated strongly with indicators of adverse cardiometabolic risk profile: it was higher with increasing body mass index (BMI) and waist circumference (WC) (P<0.001 for both). Means were significantly higher for BMI, WC, glucose, insulin, hemoglobin A1c, homeostasis model assessment, pulse pressure, C-reactive protein, total cholesterol and triglycerides in subjects with PreHTN (vs. desirable BP: P<0.05 for all). Prevalence of two or more unfavorable risk factors (other than high BP) was 30% higher in disease-free adults with PreHTN vs. desirable BP (prevalence ratio: 1.30; 95% CI: 1.22, 1.39). Detection of PreHTN (a precursor for subsequent HTN), during annual health maintenance in disease-free adults, (especially with one or more of the recognized CVD risk correlates), could become an early marker of adverse cardiometabolic risk profile. Clinical care designed to prevent progression from PreHTN to HTN (JNC 7 recommendation) may attenuate risk.

BLOOD PRESSURE, HEART RATE AND MELATONIN CYCLES SYNCHRONIZATION WITH THE SEASON, EARTH MAGNETISM AND SOLAR FLARES

Three spectral components with periods of about (~) 0.41, ~0.5 and ~1.0 year had been found with serially independent sampling in human circulating melatonin. The time series consisted of around-the-clock samples collected for 24 hours at 4-hour intervals from different patients over several years. Some of these components had been found to be circadian stage-dependent, the daytime measurements following mostly a circannual variation, whereas a half-year characterized the nighttime samples. The latter were incorporated into a circasemiannual map. The relative brevity of the series prevented a check for the coexistence of all three spectral components, even if each component seemed to have a raison d'être. In time series of transdisciplinary data, a 1.00-year synchronized component is interpreted as representing the seasons. The half-year may qualify the circannual waveform, but it is also a signature of geomagnetics. An ~0.41-year (~5-month) component is the signature of solar flares. It has been called a cis-half-year (cis = on this side of a half-year) and may be detected only intermittently. Charles L. Wolff predicted the existence, among others, of ~0.42- and ~0.56-year components as beat periods of rotations at different solar latitudes.The multiple components characterizing circulating melatonin could also be found in a (to our knowledge unique) data set of a clinically healthy scientist (RBS). Herein, we focus on vascular data self-measured by RBS as he aged from ~20 to ~60 years. A multi-component model consisting of cosine curves with periods of 0.41, 0.50 and 1.00 year was fitted to weekly means of systolic (S) and diastolic (D) blood pressure (BP) and heart rate (HR) collected ~5 times a day over 39 years by RBS. All three components can coexist for a while, although all of them are nonstationary in their characteristics and come and go by the criterion of statistical significance.Intermittently, BP and HR are synchronized selectively with one or the other aspect of RBS' physical environment, namely the seasons (at ~1.0 year), earth magnetism (at ~0.5 year) and/or solar flares (at ~0.42 year). Cosmic-biotic transfer of information, albeit hardly of energy (the biospheric amplitudes are very small) may be mediated in this set of frequency windows. As found earlier, RBS' circulation is also frequency-trapped environmentally in multidecadal windows, HR being locked into the transtridecadal Brückner, or rather Brückner-Egeson-Lockyer, BEL sunspot and terrestrial weather cycle, while his BP follows Hale's didecadal cycle in the changing polarity of sunspots.The ~0.41-year HR cycle may be associated with changes in solar flares, the cis-half-year amplitude of HR showing a cross-correlation coefficient of 0.79 with the total solar flare index (from both solar hemispheres) at a lag of ~3.2 years. The superposed time courses of these two variables indicate the presence of a shared Horrebow-Arago-Schwabe sunspot cycle of ~11 years, the cis-half-year in HR being more prominent after the total solar flare index reaches its ~11-year peak. Differences in the time-varying behavior of BP vs. HR are also described.

CLOCK genetic variation and metabolic syndrome risk: modulation by monounsaturated fatty acids

BACKGROUND

Disruption of the circadian system may be causal for manifestations of the metabolic syndrome (MetS).

OBJECTIVE

The objective was to study the associations of 5 CLOCK polymorphisms with MetS features by analyzing fatty acid (FA) composition from dietary and red blood cell (RBC) membrane sources.

DESIGN

Participants (n = 1100) in the Genetics of Lipid Lowering Drugs and Diet Network (GOLDN) study were included. Dietary intake was estimated with a validated questionnaire. Anthropometric and biochemical measurements and genotypes were determined. Postprandial lipids and the FA composition of RBC membranes were analyzed.

RESULTS

CLOCK single nucleotide polymorphisms were significantly associated with obesity and individual components of MetS. For single nucleotide polymorphism rs4580704, minor allele carriers had a 46% lower risk of hypertension than did noncarriers. The monounsaturated fatty acid (MUFA) content of RBC membranes, particularly oleic acid, changed according to CLOCK genetic variants (P < 0.05). We identified significant gene-diet interactions associated with MetS at the CLOCK locus. By dichotomizing MUFA intake, we found different effects across rs4580704 genotypes for glucose (P = 0.020) and insulin resistance (P = 0.026). The protective effect of the minor allele on insulin sensitivity was only present when MUFA intake was >13.2% of energy. We also found different effects across CLOCK 3111T-->C genotypes for saturated fatty acid intake (% of energy) (P = 0.017). The deleterious effect of gene variants on waist circumference was only found with high saturated fatty acid intakes (>11.8%).

CONCLUSIONS

CLOCK polymorphisms interact with FAs to modulate MetS traits. The dietary source and membrane content of MUFAs are implicated in the relations between alterations in the circadian system and MetS.

Circadian biology and sleep: missing links in obesity and metabolism?

This supplement highlights key talks presented at the Pennington Symposium. The collected papers provide a state of the art review of circadian biology at the basic and clinical levels in the context of nutrition, obesity and sleep medicine. Investigators from multiple disciplines attempted to translate new information concerning molecular mechanisms into practical clinical applications, as well as foster new research hypotheses and directions to this exciting field of science and medicine. Furthermore, we hope to spark the interest and attention of the next generation of scientists who will tackle the questions presented by the changing interface between technology, lifestyle and biological rhythms.

Association of an abnormal blood glucose level and morning blood pressure surge in elderly subjects with hypertension

BACKGROUND

We previously reported that morning blood pressure (BP) surge (MBPS) was an independent risk factor for stroke. We evaluated the determinants of MBPS in hypertensive patients.

METHODS

We analyzed 24-h ambulatory BP monitoring (ABPM) records in 458 hypertensive patients (mean: 72.2 +/- 8.5 years). The MBPS was calculated as the mean systolic BP (SBP) over 2 h after waking minus mean SBP during the hour of sleep that included the lowest nighttime BP. The cutoff value for identifying the top decile (the MBPS group) was defined as > or =55 mm Hg.

RESULTS

The MBPS was associated with age, fasting plasma glucose, and 24-h SBP, and they were independent and significant determinants of MBPS in multivariate analysis (age, P = 0.01; fasting plasma glucose, P < 0.01; 24-h SBP, P = 0.04) after adjustment for confounding factors of gender, body mass index (BMI), and smoking status. The subjects in the MBPS group (n = 45) were older in age (76.4 years vs. 71.8 years, P < 0.01) and had higher fasting plasma glucose (97.6 mg/dl vs. 91.4 mg/dl, P = 0.04) than those in the non-MBPS group. In logistic regression analysis, the MBPS group was associated with older age (10 years older: odds ratio (OR) 1.85, 95% confidence interval (CI) 1.26-2.72, P < 0.01) and higher fasting plasma glucose (10-mg/dl increase: OR 1.16, 95% CI 1.01-1.33, P = 0.03).

CONCLUSION

In addition to older age and higher mean 24-h SBP, higher fasting plasma glucose was associated with MBPS.