Pattern of 24-Hour Ambulatory Blood Pressure Monitoring in Type 2 Diabetic Patients with Cardiovascular Dysautonomy

Prognostic importance of cardiovascular autonomic neuropathy on cardiovascular and mortality outcomes in individuals with type 2 diabetes: The Rio de Janeiro type 2 diabetes cohort

AIMS

To investigate whether tests for cardiovascular autonomic neuropathy (CAN) and 24-hour heart rate variability (HRV) could improve the prediction for outcomes in type 2 diabetes.

METHODS

541 type 2 diabetic individuals performed tests of CAN. A subsample (313) had 24-hour HRV (the standard deviation of all normal RR intervals [SDNN] and the standard deviation of the averaged normal RR intervals for all 5 min segments [SDANN]). Multivariate Cox regressions examined the associations between CAN/low HRV with cardiovascular events (CVEs) and all-cause mortality. The improvement in risk discrimination of adding CAN/HRV was tested by C-statistics and by the Integrated Discrimination Improvement (IDI) index.

RESULTS

25% had CAN, and 17-18% had low HRV, respectively by SDANN-SDNN. Over a median follow-up of 12 years, there were 177 CVEs and 236 all-cause deaths in the whole cohort, and 96 CVEs and 129 all-cause deaths in the subsample. CAN was associated with 40% excess risks of CVEs/all-cause mortality, low HRV was associated with 2-fold higher risks of outcomes. HRV improved risk discrimination for CVEs/mortality with increases in C-statistics up to 0.039 and IDIs up to 25%.

CONCLUSIONS

Low HRV was a better predictor of outcomes than tests of CAN, and it improved risk discrimination.

Preferential impairment of parasympathetic autonomic function in type 2 diabetes

OBJECTIVE

Cardiovascular autonomic neuropathy is a known complication in type 2 diabetes (T2D). However, the extent of sympathetic dysfunction and its relation to blood pressure (BP) dysregulation is insufficiently studied. We therefore assessed the cardiovascular sympathetic function using a standardized autonomic test-battery.

RESEARCH DESIGN AND METHODS

Forty T2D patients (mean age and duration of diabetes ±SD, 65.5 ± 7.3 and 9.5 ± 4.2 years) and 40 age- and gender-matched controls were examined through autonomic testing, assessing cardiovascular responses to deep breathing, Valsalva maneuver and tilt-table testing. Additionally, 24-hour oscillometric BP and self-reported autonomic symptoms on COMPASS-31 questionnaire was recorded.

RESULTS

Patients with T2D had reduced parasympathetic activity with reduced deep breathing inspiratory:expiratory-ratio (median [IQR] T2D 1.11 [1.08-1.18] vs. controls 1.18 [1.11-1.25] (p = 0.01)), and reduced heart rate variability (p < 0.05). We found no differences in cardiovascular sympathetic function measured through BP responses during the Valsalva maneuver (p > 0.05). 24-hour-BP detected reduced night-time systolic BP drop in T2D (9.8 % ± 8.8 vs. controls 15.8 % ± 7.7 (p < 0.01)) with more patients having reverse dipping. Patients with T2D reported more symptoms of orthostatic intolerance on the COMPASS-31 (p = 0.04).

CONCLUSIONS

Patients with T2D showed reduced parasympathetic activity but preserved short-term cardiovascular sympathetic function, compared to controls, indicating autonomic dysfunction with predominantly parasympathetic impairment. Despite this, T2D patients reported more symptoms of orthostatic intolerance in COMPASS-31 and had reduced nocturnal BP dipping, indicating that these are not a consequence of cardiovascular sympathetic dysfunction.

Prevalence and Risk Factors of Sensory Symptoms in Diabetes Patients in Taiwan

BACKGROUND

Diabetic sensory neuropathy has rarely been studied in the Asian populations. This study investigated the prevalence and risk factors of sensory symptoms (SS) in the Taiwanese diabetes patients.

METHODS

A total of 1,400 diabetes patients received a health examination together with a structured questionnaire interview for three categories of abnormal sensation of numbness or tingling pain, electric shock, and skin thickness sensation on seven anatomical sites on upper limbs and six sites on lower limbs. Prevalence of SS was defined using nine different criteria, with the least stringent criterion of "any positive symptom on at least 1 site" and the most stringent criterion of "any positive symptom on at least bilateral and symmetrical 2 sites involving the lower limb." Logistic regression was used to estimate the odds ratios and their 95% confidence interval for SS by the different definitions. Fasting plasma glucose and hemoglobin A_1c were entered in separate models to avoid hypercollinearity.

RESULTS

The prevalence of SS was 14.4 and 54.0% when using the most stringent and least stringent criterion, respectively. Women consistently had a significantly higher prevalence than men did. Among the three categories of symptoms, numbness or tingling pain was the most common, and fingers and toes were the most commonly involved anatomical sites. For any symptoms, 37.1% of the patients had any symptoms on the upper limbs and 41.7% had any symptoms on the lower limbs. Female sex, diabetes duration, hemoglobin A_1c, and hypertension were associated with SS in all models.

CONCLUSIONS

Taiwanese diabetes patients may have a high prevalence of SS if a structured questionnaire is used for screening. Female sex, diabetes duration, hemoglobin A_1c, and hypertension are associated with SS.

Nocturnal antihypertensive treatment in patients with type 1 diabetes with autonomic neuropathy and non-dipping: a randomised, placebo-controlled, double-blind cross-over trial

OBJECTIVES

Cardiovascular autonomic neuropathy (CAN) and abnormal circadian blood pressure (BP) rhythm are independent cardiovascular risk factors in patients with diabetes and associations between CAN, non-dipping of nocturnal BP and coronary artery disease have been demonstrated. We aimed to test if bedtime dosing (BD) versus morning dosing (MD) of the ACE inhibitor enalapril would affect the 24-hour BP profile in patients with type 1 diabetes (T1D), CAN and non-dipping.

SETTING

Secondary healthcare unit in Copenhagen, Denmark.

PARTICIPANTS

24 normoalbuminuric patients with T1D with CAN and non-dipping were included, consisting of mixed gender and Caucasian origin. Mean±SD age, glycosylated haemoglobin and diabetes duration were 60±7 years, 7.9±0.7% (62±7 mmol/mol) and 36±11 years.

INTERVENTIONS

In this randomised, placebo-controlled, double-blind cross-over study, the patients were treated for 12 weeks with either MD (20 mg enalapril in the morning and placebo at bedtime) or BD (placebo in the morning and 20 mg enalapril at bedtime), followed by 12 weeks of switched treatment regimen.

PRIMARY AND SECONDARY OUTCOME MEASURES

Primary outcome was altered dipping of nocturnal BP. Secondary outcomes included a measurable effect on other cardiovascular risk factors than BP, including left ventricular function (LVF).

RESULTS

Systolic BP dipping increased 2.4% (0.03-4.9%; p=0.048) with BD compared to MD of enalapril. There was no increase in mean arterial pressure dipping (2.2% (-0.1% to 4.5%; p=0.07)). No difference was found on measures of LVF (p≥0.15). No adverse events were registered during the study.

CONCLUSIONS

We demonstrated that patients with T1D with CAN and non-dipping can be treated with an ACE inhibitor at night as BD as opposed to MD increased BP dipping, thereby diminishing the abnormal BP profile. The potentially beneficial effect on long-term cardiovascular risk remains to be determined.

TRIAL REGISTRATION NUMBER

EudraCT2012-002136-90; Post-results.

Prevalence of subclinical hypercortisolism in type 2 diabetic patients from the Rio de Janeiro Type 2 Diabetes Cohort Study

AIMS

Subclinical hypercortisolism was reported to be more prevalent among diabetic, obese and hypertensive patients. Our primary aim was to investigate the prevalence of subclinical hypercortisolism in patients from the Rio de Janeiro Type 2 Diabetes (RIO-T2D) Cohort; and secondarily to assess its associated factors.

METHODS

From May 2013 to August 2014, 393 diabetic outpatients underwent overnight 1mg dexamethasone suppression test (DST). Patients with non-suppressive morning cortisol (≥1.8μg/dl) were further evaluated with nocturnal salivary cortisol, two readings >0.35μg/dl were considered confirmatory for subclinical hypercortisolism.

RESULTS

One-hundred twenty-eight patients (32.6%) failed to suppress morning cortisol, and in 33 patients (8.6%) subclinical hypercortisolism was confirmed. Independent correlates of a positive DST were older age (OR: 1.04; 95% CI: 1.01-1.07; p=0.007), number of anti-hypertensive drugs in use (OR: 1.26; 95% CI: 1.05-1.50; p=0.012), longer diabetes duration (OR: 1.03; 95% CI: 1.004-1.06; p=0.023), and presence of diabetic nephropathy (OR: 1.70; 95% CI: 1.01-2.87; p=0.047). Independent correlates of confirmed subclinical hypercortisolism were a greater number of anti-hypertensive medications (OR: 1.54; 95% CI: 1.14-2.06; p=0.004), shorter diabetes duration (OR: 0.92; 95% CI: 0.87-0.98; p=0.006), and increased aortic stiffness (OR: 2.81; 95% CI: 1.20-6.57; p=0.017); metformin use was protective (OR: 0.27; 95% CI: 0.10-0.73; p=0.010).

CONCLUSION

Patients with type 2 diabetes had a high prevalence of subclinical hypercortisolism, and its presence was associated with more severe hypertension and increased aortic stiffness.

Profile of disabilities and their associated factors in patients with type 2 diabetes evaluated by the Canadian occupational performance measure: the Rio De Janeiro type 2 diabetes cohort study

PURPOSE

To investigate the profile of disability in patients with type 2 diabetes and to evaluate its associated variables.

METHOD

The Canadian Occupational Performance Measure (COPM) assessed disabilities in 475 type 2 diabetic individuals. The activities were categorised by the International Classification of Functioning, Disability and Health. The Medical Outcomes Study 36-item Short-Form Health Survey (SF-36) was used to evaluate pain, emotional and physical functioning domains of life-quality. Multivariable logistic regression assessed the independent correlates of better/worse performance.

RESULTS

Median COPM score was 4.5 (interquartile range 3-6). Problems in mobility (53.6%), self-care (21.1%) and daily-life (13.0%) were most frequently self-reported. Presence of restriction/pain in the upper limbs (odds ratio [OR]: 1.66; 95% CI: 1.11-2.47; p=0.013) and of peripheral neuropathy (OR: 1.64; 95% CI: 1.06-2.53; p=0.026) were associated with greater chance of worse performance. Higher values of SF-36 in pain and emotional domains (each 10 point increase; OR: 0.92 95% CI: 0.85-0.98; p=0.011; OR: 0.96; 95% CI: 0.92-1.00; p=0.063, respectively) and physical activity (OR: 0.63; 95% CI: 0.41-0.98; p=0.042) were associated with better performance.

CONCLUSIONS

Type 2 diabetic patients frequently reported disabilities in mobility, self-care and daily-life domains; and its associated factors were the presence of depression, upper limb pain and diabetic peripheral neuropathy. Implications for Rehabilitation The Canadian Occupational Performance Measure (COPM) instrument can be applied to patients with diabetes, as it identifies several disabilities, mostly in mobility, self-care and domestic life areas. Rehabilitation directed to upper limb pain/limitation and to lower limb peripheral neuropathy shall be implemented and may improve diabetic patients' performance and quality of life. A patient-centered rehabilitation strategy, guided by the COPM, may enable greater independence and autonomy, but this should be confirmed in future intervention studies.

Prognostic impact of clinic and ambulatory blood pressure components in high-risk type 2 diabetic patients: the Rio de Janeiro Type 2 Diabetes Cohort Study

BACKGROUND

The prognostic importance of tight clinic blood pressure (BP) control is controversial in diabetic patients. The objective was to investigate the prognostic impact of clinic and ambulatory BPs for cardiovascular morbidity and mortality in type 2 diabetes.

METHODS

In a prospective cohort study, 565 type 2 diabetic patients had clinical, laboratory and ambulatory BP monitoring (ABPM) data obtained at baseline and during follow-up. The primary endpoints were a composite of fatal and nonfatal cardiovascular events and all-cause mortality. Multivariable Cox survival and splines regression analyses assessed associations between each BP component [SBP, DBP and pulse pressure (PP)] and the endpoints.

RESULTS

After a median follow-up of 5.75 years, 88 total cardiovascular events and 70 all-cause deaths occurred. After adjustments for cardiovascular risk factors, clinic SBP and DBPs were predictive of the composite endpoint but not of all-cause mortality, whereas all ambulatory BP components were predictors of both endpoints. Ambulatory systolic and PPs were the strongest predictors and achieved ambulatory BPs during follow-up improved risk prediction in relation to baseline values. When categorized at clinically relevant cut-off values, risk began only at clinic BPs at least 140/90 mmHg, whereas for ambulatory BPs it began at lower values (≥120/75 mmHg for the 24-h period).

CONCLUSION

ABPM provides more valuable information regarding cardiovascular risk stratification than office BPs and should be performed, if possible, in every high-risk type 2 diabetic patient. Achieved 24-h ambulatory BPs less than 120/75 mmHg are associated with significant cardiovascular protection and, if confirmed by other studies, may be considered as BP treatment targets.

Nocturnal antihypertensive treatment in patients with type 1 diabetes with autonomic neuropathy and non-dipping of blood pressure during night time: protocol for a randomised, placebo-controlled, double-blind, two-way crossover study

INTRODUCTION

Cardiac autonomic neuropathy (CAN) and elevated nocturnal blood pressure are independent risk factors for cardiovascular disease in patients with diabetes. Previously, associations between CAN, non-dipping of nocturnal blood pressure and coronary artery calcification have been demonstrated. The present protocol describes a trial to test the efficacy of bedtime dosing of the ACE inhibitor enalapril on night time blood pressure and left ventricular mass in patients with type 1 diabetes.

MATERIALS AND METHODS

In a randomised, double-blind, two-way cross-over study, 24 normoalbuminuric patients with type 1 diabetes with CAN will be treated for 12 weeks with either morning or bedtime dosing of 20 mg enalapril, followed by 12 weeks of switched treatment regimen. During each treatment period, two 24 h ambulatory blood pressure measurements will be performed and after each treatment period left ventricular mass will be determined by multisliced CT. Primary end points will be reduction in blood pressure and reduction in left ventricular mass.

ETHICS AND DISSEMINATION

The study has been approved by the Danish Medicines Agency, the Scientific-Ethical Committee of the Capital Region of Denmark and the Danish Data Protection Agency. An external monitoring committee (the Good Clinical Practice Unit at Copenhagen University Hospital) will oversee the study. The results of the study will be presented at national and international scientific meetings and publications will be submitted to peer-reviewed journals.

TRIAL REGISTRATION NUMBER

EudraCT (2012- 002136-90).

Relationships between reduced heart rate variability and pre-clinical cardiovascular disease in patients with type 2 diabetes

AIMS

Reduced heart rate variability (HRV), an early sign of diabetic cardiovascular autonomic neuropathy (CAN), is associated with worse cardiovascular outcomes. The objective was to evaluate relationships between HRV parameters and three pre-clinical cardiovascular disease markers (left ventricular hypertrophy [LVH], aortic stiffness and carotid atherosclerosis) in type 2 diabetes.

METHODS

In a cross-sectional study, 313 patients with type 2 diabetes performed 24-h Holter monitoring, carotid ultrasonography (intima-media thickness and plaques measurements), aortic pulse wave velocity measurement and echocardiography (left ventricular mass index [LVMI] measurement). Time-domain HRV parameters were the standard deviation of all normal RR intervals (SDNN), the standard deviation of the averaged normal RR intervals for all 5min segments (SDANN), the root mean square of differences between adjacent R-R intervals (rMSSD), and the percentage of adjacent R-R intervals that varied by >50ms (pNN50). Multivariate linear and logistic regressions assessed associations between HRV parameters and the three markers of pre-clinical cardiovascular disease.

RESULTS

Patients with reduced HRV had longer diabetes duration, greater prevalences of microvascular complications, lower physical fitness, and higher heart rate, glycated hemoglobin, albuminuria and LVMI than patients with normal HRV. On multivariate regressions, after adjustments for several confounders, reduced SDNN and SDANN were independently associated with LVH and aortic stiffness. No HRV parameter was associated with carotid atherosclerosis.

CONCLUSIONS

Two reduced HRV parameters, SDNN and SDANN, which reflect cardiovascular autonomic imbalance, were associated with LVH and aortic stiffness, markers of pre-clinical cardiovascular disease. These findings may offer insights into physiopathological mechanisms linking CAN to worse cardiovascular prognosis.

Comparison of lower extremity atherosclerosis in diabetic and non-diabetic patients using multidetector computed tomography

Background

Lower extremity atherosclerosis (LEA) is among the most serious diabetic complications and leads to non-traumatic amputations. The recently developed dual-source CT (DSCT) and 320- multidetector computed tomography (MDCT) may help to detect plaques more precisely. The aim of our study was to evaluate the differences in LEA between diabetic and non-diabetic patients using MDCT angiography.

Methods

DSCT and 320-MDCT angiographies of the lower extremities were performed in 161 patients (60 diabetic and 101 non-diabetic). The plaque type, distribution, shape and obstructive natures were compared.

Results

Compared with non-diabetic patients, diabetic patients had higher peripheral neuropathy, history of cerebrovasuclar infarction and hypertension rates. A total of 2898 vascular segments were included in the analysis. Plaque and stenosis were detected in 681 segments in 60 diabetic patients (63.1%) and 854 segments in 101 non-diabetic patients (46.9%; p <0.05). Regarding these plaques, diabetic patients had a higher incidence of mixed plaques (34.2% vs. 27.1% for non-diabetic patients). An increased moderate stenosis rate and decreased occlusion rate were observed in diabetic patients relative to non-diabetic patients (35.8% vs. 28.3%; and 6.6% vs. 11.4%; respectively). In diabetic patients, 362 (53.2%) plaques were detected in the distal lower leg segments, whereas in non-diabetic patients, 551 (64.5%) plaques were found in the proximal upper leg segments. The type IV plaque shape, in which the full lumen was involved, was detected more frequently in diabetic patients than in non-diabetic patients (13.1% vs. 8.2%).

Conclusion

Diabetes is associated with a higher incidence of plaque, increased incidence of mixed plaques, moderate stenosis and localisation primarily in the distal lower leg segments. The advanced and non-invasive MDCT could be used for routine preoperative evaluations of LEA.

Factors associated with abnormal T-wave axis and increased QRS-T angle in type 2 diabetes

Frontal plane T-wave axis and QRS-T angle are novel electrocardiographic ventricular repolarization parameters that have been scarcely evaluated in type 2 diabetes. The aim was to investigate the factors associated with these parameters of abnormal ventricular repolarization in a cross-sectional analysis of 594 patients with type 2 diabetes. Clinical, laboratory, 2D-echocardiographic, ambulatory blood pressure (BP) monitoring, aortic pulse wave velocity (PWV) and carotid ultrasonographic data were obtained. Digital 12-lead ECG was recorded, and frontal plane T-wave axis and QRS-T angle were automatically measured. T-wave axis was considered abnormal if >75° or <15° and QRS-T angle if ≥73° in men and ≥67° in woman. Associations were assessed by bivariate tests and multivariate logistic regressions. One hundred and four (20.9 %) patients had abnormal T-wave axis, and 84 (14 %) had increased QRS-T angle. Patients with abnormal ventricular repolarization were older and had greater prevalence of micro- and macrovascular diabetic complications than patients with normal repolarization. They had higher office and ambulatory BPs, greater prevalence of the non-dipping pattern, and greater left ventricular mass, aortic PWV and carotid intima-media thickness. On multivariate analysis, abnormal ventricular repolarization parameters were independently associated with left ventricular hypertrophy, non-dipping pattern, higher ambulatory systolic BPs, glycated hemoglobin and common carotid intima-media thickness, and with the presence of coronary artery disease. In conclusion, abnormal frontal plane T-wave axis and QRS-T angle are independently associated with several markers of pre-clinical atherosclerotic disease; whether these associations represent additional cardiovascular risk in type 2 diabetes shall be confirmed in prospective studies.

Prognostic impact of aortic stiffness in high-risk type 2 diabetic patients: the Rio deJaneiro Type 2 Diabetes Cohort Study

OBJECTIVE

The prognostic importance of carotid-femoral pulse wave velocity (PWV), the gold standard measure of aortic stiffness, has been scarcely investigated in type 2 diabetes and never after full adjustment for potential confounders. The aim was to evaluate the prognostic impact of carotid-femoral PWV for cardiovascular morbidity and all-cause mortality in a cohort of 565 high-risk type 2 diabetic patients.

RESEARCH DESIGN AND METHODS

Clinical, laboratory, ambulatory blood pressure (BP) monitoring, and carotid-femoral PWV data were obtained at baseline. The primary end points were a composite of fatal and nonfatal cardiovascular events and all-cause mortality. Multiple Cox survival analysis was used to assess the associations between carotid-femoral PWV, as a continuous variable and categorized at 10 m/s, and the end points.

RESULTS

After a median follow-up of 5.75 years, 88 total cardiovascular events and 72 all-cause deaths occurred. After adjustments for potential cardiovascular risk factors, including micro- and macrovascular complications, ambulatory BP, and metabolic control, carotid-femoral PWV was predictive of the composite end point but not of all-cause mortality both as a continuous variable (hazard ratio 1.13 [95% CI 1.03-1.23], P = 0.009 for increments of 1 m/s) and as categorized at 10 m/s (1.92 [1.16-3.18], P = 0.012). On sensitivity analysis, carotid-femoral PWV was a better predictor of cardiovascular events in younger patients (<65 years), in those with microvascular complications, and in those with poorer glycemic control (HbA1c ≥7.5% [58.5 mmol/mol]).

CONCLUSIONS

Carotid-femoral PWV provides cardiovascular risk prediction independent of standard risk factors, glycemic control, and ambulatory BPs and improves cardiovascular risk stratification in high-risk type 2 diabetes.

Factors associated with carotid intima-media thickness and carotid plaques in type 2 diabetic patients

OBJECTIVE

Factors associated with carotid atherosclerosis are unclear in type 2 diabetic patients. The aim was to investigate the independent correlates of carotid intima-media thickness (IMT) and plaques in these individuals.

METHODS

In a cross-sectional study, we measured carotid IMT at three sites (common carotid, bifurcation and internal carotid artery) and the severity of extracranial carotid artery (ECCA) atherosclerosis by plaque score in 441 type 2 diabetic patients. Nontraditional cardiovascular risk factors [ambulatory blood pressures (BPs), aortic stiffness, C-reactive protein and ankle-brachial index) were obtained. Multivariate linear and logistic regressions assessed the independent correlates of carotid IMT and ECCA plaque score.

RESULTS

Patients with greater carotid IMT or plaque scores had worse clinical and laboratory profile than those with lower IMT and plaque scores, including higher BPs, aortic stiffness and prevalences of diabetic complications. On multivariate analysis, carotid IMT and plaques were mainly associated with older age, male sex, current-past smoking and ambulatory BPs, but not with clinic BPs. Night-time pulse pressure was the most important modifiable determinant of increased carotid IMT. No microvascular complication was independently associated with carotid atherosclerosis, except retinopathy for plaque score. Additionally, internal carotid IMT and plaque score were associated with ankle-brachial index in the subgroup of patients without macrovascular diseases.

CONCLUSION

In type 2 diabetic patients, older age, male sex, smoking status and ambulatory BPs, particularly night-time pulse pressure, were the main independent correlates of ultrasonographic carotid atherosclerosis. This finding reinforces the importance of ambulatory BP monitoring in type 2 diabetes management.

Heart rate variability and sensorimotor polyneuropathy in type 1 diabetes

OBJECTIVE

Reduced heart rate variability (HRV) is classically viewed as an early phenomenon in diabetic sensorimotor polyneuropathy (DSP). We aimed to determine the characteristics of HRV across the spectrum of clinical DSP in type 1 diabetes.

RESEARCH DESIGN AND METHODS

Eighty-nine diabetic subjects and 60 healthy volunteers underwent assessment of RR interval variation (RR(var)) during deep breathing and clinical and electrophysiological examination. We examined the distribution of age-standardized RR(var) across the spectrum of clinical DSP, identified variables associated with RR(var) in multivariate regression, and compared RR(var) with validated measures of neuropathy.

RESULTS

Age-standardized RR(var) had a significant, step-wise, inverse relationship with ordinal categories of increasing DSP severity (β = -5.4, P < 0.0001) among subjects with diabetes. Case subjects with DSP had substantially lower age-standardized RR(var) compared with diabetic control subjects without DSP (β = -5.2, P < 0.01), although there was substantial overlap of RR(var) between diabetic case subjects and control subjects and the healthy volunteer cohort. In multivariate analysis, advanced age was independently associated with lower RR(var) in both healthy volunteers and diabetic subjects, whereas higher glycated hemoglobin A(1c) and systolic blood pressure were independently associated with lower RR(var) in diabetic subjects. RR(var) had a significant association with validated measures of large and small fiber neuropathy.

CONCLUSIONS

HRV may be a biomarker for clinical DSP and is associated cross-sectionally with both early and late measures of neuropathy. The low HRV observed in some control subjects without DSP and in most case subjects with severe DSP may signify that HRV has different prognostic implications in these groups, requiring further longitudinal study.

Thresholds of ambulatory blood pressure associated with chronic complications in type 2 diabetes

BACKGROUND

Diagnostic cut-off values for ambulatory blood pressure monitoring (ABPM) in diabetic patients are not established. The aim was to investigate associations between office and ambulatory blood pressures (BPs) and diabetic chronic complications and to establish optimal threshold ambulatory BP values regarding the likehood of having microvascular complications in type 2 diabetes.

METHODS

In a cross-sectional design, clinical, laboratory, and 24-h ABPM data were obtained in 550 type 2 diabetic patients. Multivariate logistic regression assessed the associations between office and ambulatory BPs and diabetic micro and macrovascular complications. Optimal threshold values for ambulatory BPs (daytime, night-time, and 24 h) were established by examining the best combination of systolic (SBP) and diastolic BP (DBP) that maximized the odds ratios (ORs) of having each microvascular complication.

RESULTS

After multivariate adjustment for all potential confounders, ambulatory SBPs were more strongly associated with diabetic complications than office BPs, except for retinopathy and nephropathy, in which both were equivalent. In general, night-time BPs were stronger correlates than daytime BPs. The optimal threshold ambulatory BP values were 125/75 mm Hg for daytime, 110/65 mm Hg for night-time, and 120/75 mm Hg for the 24-h period, with odds ranging from 1.7- to 2.3-fold of having each microvascular complication.

CONCLUSIONS

Except for retinopathy and advanced nephropathy, ambulatory BPs are better correlates of chronic complications than office BPs in type 2 diabetes. The association of microvascular complications with lower ambulatory BP levels than those reported as normal for nondiabetic patients may indicate that lower cut-off values for ambulatory BPs might be considered in type 2 diabetic patients.

Altered clock gene expression and vascular smooth muscle diurnal contractile variations in type 2 diabetic db/db mice

This study was designed to determine whether the 24-h rhythms of clock gene expression and vascular smooth muscle (VSM) contractile responses are altered in type 2 diabetic db/db mice. Control and db/db mice were euthanized at 6-h intervals throughout the day. The aorta, mesenteric arteries, heart, kidney, and brain were isolated. Clock and target gene mRNA levels were determined by either real-time PCR or in situ hybridization. Isometric contractions were measured in isolated aortic helical strips, and pressor responses to an intravenous injection of vasoconstrictors were determined in vivo using radiotelemetry. We found that the 24-h mRNA rhythms of the following genes were suppressed in db/db mice compared with control mice: the clock genes period homolog 1/2 (Per1/2) and cryptochrome 1/2 (Cry1/2) and their target genes D site albumin promoter-binding protein (Dbp) and peroxisome proliferator-activated receptor-γ (Pparg) in the aorta and mesenteric arteries; Dbp in the heart; Per1, nuclear receptor subfamily 1, group D, member 1 (Rev-erba), and Dbp in the kidney; and Per1 in the suprachiasmatic nucleus. The 24-h contractile variations in response to phenylephrine (α(1)-agonist), ANG II, and high K(+) were significantly altered in the aortas from db/db mice compared with control mice. The diurnal variations of the in vivo pressor responses to phenylephrine and ANG II were lost in db/db mice. Moreover, the 24-h mRNA rhythms of the contraction-related proteins Rho kinase 1/2, PKC-potentiated phosphatase inhibitory protein of 17 kDa, calponin-3, tropomyosin-1/2, and smooth muscle protein 22-α were suppressed in db/db mice compared with control mice. Together, our data demonstrated that the 24-h rhythms of clock gene mRNA, mRNA levels of several contraction-related proteins, and VSM contraction were disrupted in db/db mice, which may contribute to the disruption of their blood pressure circadian rhythm.

High fitness is associated with a better cardiovascular risk profile in patients with type 2 diabetes mellitus

Novel cardiovascular risk markers, such as ambulatory blood pressure (BP) and aortic stiffness, have been proposed. The aim of this study was to investigate the relationship between physical fitness and some of these risk markers in 575 type 2 diabetic patients. In a cross-sectional design, clinical, laboratory, echocardiographic, aortic pulse wave velocity and 24-h ambulatory BP monitoring data were obtained. Fitness was self-reported using a standard questionnaire of daily activities, and then assessed as belonging to one of the three categories: low (<4 metabolic equivalents (METs)), moderate (≥ 4 to <7 METs) and high fitness (≤ 7 METs). In a random sub-sample of 265 patients, self-reported fitness was confirmed by a standard treadmill test. Statistical analysis was carried out, using tests including bivariate tests among the three categories and multivariate logistic regression. Agreement between self-reported and measured fitness was substantial (weighted κ: 0.63). High fitness patients were younger, frequently male, had a decreased prevalence of degenerative complications, lower office and ambulatory BP levels, particularly during the night and had an increased prevalence of the normal nocturnal dipping pattern. High fitness patients also had lower hemoglobin A1c and C-reactive protein levels, a decreased prevalence of left ventricular hypertrophy and increased aortic stiffness. On multiple logistic regression, after adjustments for several confounders, high fitness was independently associated with a higher likelihood of having low C-reactive protein (odds ratio (OR): 2.3, 95% confidence interval (CI): 1.3-3.9), controlled nighttime BP (OR: 2.3, 95% CI: 1.4-3.8), normal dipping pattern (OR: 2.1, 95% CI: 1.2-3.5) and low aortic stiffness (OR: 2.5, 95% CI: 1.3-4.8). Patients with moderate fitness had intermediate OR. In conclusion, a moderate to high level of physical fitness was independently associated with several favorable intermediate cardiovascular risk markers, which may contribute to decreasing the burden of morbi-mortality in patients with type 2 diabetes.

Uncontrolled isolated office hypertension is associated with subclinical markers of cardiovascular disease in hypertensive type 2 diabetic patients

Isolated office hypertension (IOH) has been associated with structural cardiac abnormalities; however, its relation to worse cardiovascular prognosis remains uncertain. Less is known regarding the consequences of uncontrolled IOH in treated hypertensives. The aim was to investigate whether uncontrolled IOH was independently associated with two subclinical markers of cardiovascular disease, aortic stiffness and left ventricular hypertrophy (LVH). Clinical laboratory and 24-h ambulatory blood pressure (BP) data were obtained in 523 hypertensive patients with type 2 diabetes. Controlled office-ambulatory hypertension was defined by office blood pressure <140/90 mm Hg and 24-h BP <130/80 mm Hg, whereas uncontrolled IOH by office blood pressure> or =140/90 mm Hg and 24-h BP <130/80 mm Hg. Arterial stiffness was assessed by carotid-femoral pulse wave velocity (PWV) and left ventricular mass index (LVMI) by echocardiography. Statistics included multivariate linear and logistic regressions. According to BP patterns, 152 patients (29.1%) had controlled office-ambulatory hypertension, and 172 (32.9%) had uncontrolled IOH. Patients with uncontrolled IOH had greater LVMI (62.0+/-21.9 vs. 52.9+/-17.0 g m(-2.7), P<0.001) and PWV (11.5+/-2.4 vs. 10.2+/-2.1 m s(-1), P<0.001) than those with controlled hypertension. On linear model, after adjustment for several potential confounders, patients with uncontrolled IOH persisted with higher PWV (P=0.003) and LVMI (P=0.015). On logistic regression, the presence of uncontrolled IOH was independently associated with 2.7-fold (95% CI: 1.3-5.5) and 2.1-fold (95% CI: 1.1-4.0) higher risks of having increased aortic stiffness and LVH, respectively. In conclusion, uncontrolled IOH is associated with increased aortic stiffness and LVH in hypertensive type 2 diabetic patients. This may be a link to augmented cardiovascular risk.

Microvascular degenerative complications are associated with increased aortic stiffness in type 2 diabetic patients

OBJECTIVE

Diabetes is a risk factor for increased arterial stiffness; however, few studies had investigated its associated factors. The aim was to evaluate the correlates of increased arterial stiffness in type 2 diabetes, particularly the relationships with microvascular complications.

METHODS

482 type 2 diabetic patients without peripheral arterial disease were evaluated in a cross-sectional study. Clinical (including tests of cardiovascular dysautonomy), laboratory, ECG, echocardiographic and 24h ambulatory blood pressure monitoring data were obtained. Arterial stiffness was assessed by carotid-femoral (aortic) and carotid-radial (peripheral) pulse wave velocity (PWV) measurements. Statistics included multivariate linear and logistic regressions to investigate the independent correlates of increased arterial stiffness.

RESULTS

No diabetes-related variable was associated with peripheral arterial stiffness. 148 patients (31%) had increased aortic PWV (>12m/s). On multiple linear regression, retinopathy and nephropathy, besides age, heart rate, 24h pulse pressure, diabetes duration, dyslipidemia and number of antihypertensive drugs in use, were independently associated with aortic PWV. On multivariate logistic regression increased aortic stiffness was associated with retinopathy (odds ratio: 3.83, 95% confidence interval [CI]: 2.24-6.56, p<0.001) and peripheral neuropathy (odds ratio: 1.79, 95%CI: 1.06-3.02, p=0.03) after adjusting for possible confounding variables. Other variables associated with increased aortic stiffness were older age, heart rate, diabetes duration, 24h pulse pressure, dyslipidemia and physical inactivity.

CONCLUSIONS

In type 2 diabetic patients, increased central arterial stiffness is associated with the presence of microvascular complications independent of other established determinants of aortic stiffness.