Cardiovascular autonomic neuropathy due to diabetes mellitus: clinical manifestations, consequences, and treatment

Low muscle strength rather than low muscle mass is associated with cardiovascular autonomic neuropathy in patients with type 2 diabetes

Several studies have investigated whether sarcopenia is associated with diabetic microvascular complications, but very few have examined associations between sarcopenia and cardiovascular autonomic neuropathy (CAN) in patients with type 2 diabetes mellitus (T2DM). Therefore, we investigated associations of muscle strength (handgrip strength [HGS]) and mass (appendicular skeletal muscle mass index [ASMI]) and CAN in patients with T2DM. We enrolled 342 patients in this retrospective, cross-sectional study. Cardiovascular reflex tests were used to assess CAN according to Ewing's protocol. Relative HGS was determined after normalizing absolute HGS to body weight (HGS/body weight [kg]). We defined low HGS and low ASMI according to a consensus report of the Asian Group for Sarcopenia. Logistic regression analyses were carried out to assess the associations between relative HGS or ASMI quartiles and the presence of CAN in patients with T2DM. The prevalence rates of CAN, low HGS, and low ASMI in the study subjects were 34.8%, 17.3%, and 18.7%, respectively. Low HGS was significantly more prevalent in patients with CAN than those without CAN (23.5% vs. 13.9%, p = 0.025). The CAN scores were significantly and negatively correlated with relative HGS but not with ASMI. Relative HGS was negative correlated with age, glycated hemoglobin, fasting plasma glucose, hsCRP, body mass index, and HOMA-IR and positively correlated with ASMI. The prevalence of CAN gradually increased with decreasing quartile of relative HGS (28.4% in Q4, 31.8% in Q3, 34.2% in Q2, and 45.3% in Q1, p = 0.02 for trend). Multivariable-adjusted prevalence ratios (PRs) for CAN, determined by comparing the first, second, and third quartiles with the fourth quartile of relative HGS, were 4.4 with a 95% confidence interval (95% CI) of [1.1 to 17.3]), 2.3 (95% CI [0.8 to 6.9]), and 1.2 (95% CI [0.4 to 3.7]), respectively. The prevalence of CAN and the PRs (95% [CI]) for CAN based on ASMI were not statistically significant. Our findings suggest that low muscle strength rather than low muscle mass was significantly associated with the presence of CAN. Therefore, HGS testing could help identify patients who would benefit from screening for earlier diagnosis of CAN.

A therapeutic challenge relating to the association of orthostatic hypotension and supine hypertension in a patient with cardiac autonomic neuropathy: a case report

BACKGROUND

Cardiac autonomic neuropathy is a highly prevalent pathology in the diabetic population, and is the leading cause of death in this population. Orthostatic hypotension is the main clinical manifestation of the disease. In some patients, this orthostatic hypotension is associated with supine hypertension, posing a therapeutic challenge since treatment of one entity may aggravate the other. The challenge is to manage each of these two hemodynamic opposites without exposing the patient to a life-threatening risk of severe hypotension or hypertension.

CASE PRESENTATION

We report a case of a 62-year-old ethnic Moroccan woman who has cardiovascular risk factors such as type 2 diabetes, arterial hypertension, and dyslipidemia. The patient's symptoms included dizziness, tremors, morning sickness, palpitations, and intolerance to exertion. Given her symptomatology, the patient benefited from an exploration of the autonomic nervous system through cardiovascular reactivity tests (Ewing tests), which confirmed the diagnosis of cardiac autonomic neuropathy. In addition to orthostatic hypotension, our patient had supine arterial hypertension, complicating management. To treat orthostatic hypotension, we advised the patient to avoid the supine position during the day, to raise the head of the bed during the night, and to have a sufficient fluid intake, with a gradual transition from decubitus to orthostatism and venous restraint of the lower limbs. Supine hypertension was treated with transdermal nitrates placed at bedtime and removed 1 hour before getting up. One week after the introduction of treatment, the patient reported a clear regression of functional symptoms, with an improvement in her quality of life. Improvement in symptomatology was maintained during quarterly follow-up consultations.

CONCLUSIONS

Cardiac autonomic neuropathy is a very common pathology in diabetic patients. It is a serious condition with a life-threatening prognosis. Its management must be individualized according to the symptomatology and profile of each patient. The treatment of patients with orthostatic hypotension and supine hypertension requires special attention to ensure that each entity is treated without aggravating the other.

Correlation of serum HDL level with HRV indices using multiple linear regression analysis in patients with type 2 diabetes mellitus

AIMS/OBJECTIVES

To determine the correlation between serum HDL levels with HRV indices in patients with T2DM.

MATERIALS AND METHODS

The study included 120 type 2 DM patients aged 35-65 years of either sex by simple random sampling. One-minute HRV was analyzed during deep breathing and fasting serum HDL levels was estimated in all patients. Data were analyzed using SPSS 20.0. Karl Pearson's correlation coefficient for relationship and Multiple linear regression analysis was applied for assessment of the influence of independent variables (HRV Indices) on a dependent variable (serum HDL levels). P < 0.05 was considered statistically significant.

RESULTS

Significant negative correlation was observed between serum HDL levels with Mean HR (r = 0.7422, p < 0.001)), LFnu (r = -0.6172, p < 0.001) and ratio of LF/HF (r = 0.5333, p < 0.001). But significant positive correlation was observed between serum HDL levels with HFnu (r = 0.6438, p < 0.001), SDNN, (r = 0.7495, p < 0.001)), RMSSD (r = 0.6348, p < 0.001) and pNN50 % (r = 0.8187, p < 0.001).

CONCLUSIONS

Our findings suggest that HDL-C level and all other HRV indices are dependent on each other in patients with T2DM. Most of these patients with low HDL-C level might be associated with autonomic imbalance; this in turn is detected by a simple bedside test of 1-minute HRV during deep breathing.

The Role of Angiotensin Receptor Blockers in the Personalized Management of Diabetic Neuropathy

Neuropathy is a frequent complication of diabetes mellitus (DM) and is associated with the increased risk ofamputation and vascular events. Tight glycemic control is an important component inthe prevention of diabetic neuropathy. However, accumulating data suggest that angiotensin receptor blockers (ARBs) might also be useful in this setting. We discuss the findings of both experimental and clinical studies that evaluated the effects of ARBs on indices of diabetic neuropathy. We also review the implicated mechanisms of the neuroprotective actions of these agents. Overall, it appears that ARBs might be a helpful tool for preventing and delaying the progression of diabetic neuropathy, but more data are needed to clarify their role in the management of this overlooked complication of DM.

Prediction of cardiac autonomic neuropathy using a machine learning model in patients with diabetes

Background

Cardiac autonomic neuropathy (CAN) is a diabetes-related complication with increasing prevalence and remains challenging to detect in clinical settings. Machine learning (ML) approaches have the potential to predict CAN using clinical data. In this study, we aimed to develop and evaluate the performance of an ML model to predict early CAN occurrence in patients with diabetes.

Methods

We used the diabetes complications screening research initiative data set containing 200 CAN-related tests on more than 2000 participants with type 2 diabetes in Australia. Data were collected on peripheral nerve functions, Ewing's tests, blood biochemistry, demographics, and medical history. The ML model was validated using 10-fold cross-validation, of which 90% were used in training the model and the remaining 10% was used in evaluating the performance of the model. Predictive accuracy was assessed by area under the receiver operating curve, and sensitivity, specificity, positive predictive value, and negative predictive value.

Results

Of the 237 patients included, 105 were diagnosed with an early stage of CAN while the remaining 132 were healthy. The ML model showed outstanding performance for CAN prediction with receiver operating characteristic curve of 0.962 [95% confidence interval (CI) = 0.939-0.984], 87.34% accuracy, and 87.12% sensitivity. There was a significant and positive association between the ML model and CAN occurrence (p < 0.001).

Conclusion

Our ML model has the potential to detect CAN at an early stage using Ewing's tests. This model might be useful for healthcare providers for predicting the occurrence of CAN in patients with diabetes, monitoring the progression, and providing timely intervention.

Thermal quantitative sensory testing as a screening tool for cardiac autonomic neuropathy in patients with diabetes mellitus

INTRODUCTION

Electrophysiological diagnosis of cardiac autonomic neuropathy (CAN) is based on the evaluation of cardiovascular autonomic reflex tests (CARTs). CARTs are relatively time consuming and must be performed under standardized conditions. This study aimed to determine whether thermal quantitative sensory testing (TQST) can be used as a screening tool to identify patients with diabetes at a higher risk of CAN.

METHODS

Eighty-five patients with diabetes and 49 healthy controls were included in the study. Neurological examination, CARTs, TQST, biochemical analyses, and neuropathy symptom questionnaires were performed.

RESULTS

CAN was diagnosed in 46 patients with diabetes (54%). CAN-positive patients with diabetes had significantly higher warm detection thresholds (WDT) and significantly lower cold detection thresholds (CDT) in all tested regions (thenar, tibia, and the dorsum of the foot). CDT on the dorsum < 21.8°C in combination with CDT on the tibia < 23.15°C showed the best diagnostic ability in CAN prediction, with 97.4 % specificity, 60.9% sensitivity, 96.6% positive predictive value, and 67.3% negative predictive value.

CONCLUSION

TQST can be used as a screening tool for CAN before CART.

Cardiovascular Autonomic Reflex Tests and 7 Heart Rate Variability Indices for Early Diagnosis of Cardiovascular Autonomic Neuropathy in Type 2 Diabetes Individuals

BACKGROUND

Cardiovascular autonomic neuropathy (CAN) is a common complication of type 2 Diabetes mellitus (T2D), and prevalence varies according to the methodology used. CAN should be diagnosed in the subclinical stage when an intensive treatment of T2D could avoid the progression to irreversible phases.

OBJECTIVE

Determine the prevalence of early involvement (EI) of CAN in T2D individuals comparing two methodologies.

METHODS

This was a cross-sectional study that included 183 T2D individuals who were monitored in a Tertiary centre. The diagnosis of CAN was based on the results of four cardiovascular autonomic reflex tests (CARTs: expiration-inspiration index, Valsalva maneuver, orthostatic test, and changes in blood pressure after standing) and of seven heart rate variability (7HRV) indices (CARTs plus the spectral analysis). The findings were validated in an independent cohort comprised of 562 T2D individuals followed in a Primary care setting.

RESULTS

With the use of 7HRV, 30.6% and 77.8% of individuals in the Tertiary and in the Primary centers, respectively, were classified as without CAN; 25.1% and 15.3% as EI and 44.3% and 6.9% as definitive CAN, respectively. The use of CARTs decreased the proportion of individuals without CAN in both centers (7.1% and 47%) and increased the frequency of EI (30.6% and 36.6%) and definitive CAN (62.3% and 16.4%), respectively. The concordance between both evaluated methodologies was weak.

CONCLUSION

Higher proportions of T2D individuals were diagnosed with EI and with definitive CAN with the use of CARTs.

Normative data on cardiovascular autonomic function in Greenlandic Inuit

INTRODUCTION

Diabetes is increasing among Greenlandic Inuit; however, the prevalence of cardiovascular autonomic neuropathy (CAN) is yet unknown. The assessment of CAN requires an ability to differentiate between normal and abnormal. The aim was to establish normative reference data of cardiovascular autonomic function in Greenlandic Inuit.

RESEARCH DESIGN AND METHODS

In this cross-sectional study, cardiovascular autonomic function was evaluated in participants without diabetes during the Greenlandic Population Study 2018 and in the town Qasigiannguit in 2020. Assessment included cardiovascular autonomic reflex tests (CARTs) and power spectral analysis of heart rate variability (HRV). Normative reference limits were estimated by applying piecewise linear quantile regression models at the fifth percentile. Models were adjusted for age and sex.

RESULTS

Based on examinations of 472 participants (61.7% females), normative reference data was established for all outcomes. Mean age was 54 years (SD 13.1). Higher age was inversely associated with all outcomes of CARTs and HRV. A linear fall in cardiovascular autonomic function tended to level off beyond age of 60 or 70 years for supine-to-upright position ratio and low frequency power. However, the number of observations in subjects older than 60 or 70 years was limited, which may have caused a flattening of the curve around that age. No other associations were found.

CONCLUSIONS

The general level of the CARTs and HRV for all age groups is notably lower than in previous studies from other nationalities. We speculate that sociodemographic and cultural aspects of the Greenlandic Inuit population including body mass index, smoking, physical activity and alcohol consumption may have affected the cardiovascular autonomic function.

Clinical significance of heart rate variability for the monitoring of cardiac autonomic neuropathy in end-stage renal disease patients

BACKGROUND AND AIMS

The aim of this study is to determine whether the measurement of continuous heart rate variability (HRV) is useful in the evaluation of cardiac autonomic neuropathy (CAN) in end-stage renal disease (ESRD) patients.

METHODS AND RESULTS

This cross-sectional study was performed at Seoul St. Mary's hospital between June 2017 and February 2018. Seventy-seven ESRD patients, and 29 healthy controls (HCs) were asked to wear a continuous ambulatory HRV monitor for 24 h. General cardiac function was evaluated using transthoracic echocardiogram (TTE), pulse wave velocity (PWV), coronary calcium scoring (CCS), and 24-h ambulatory blood pressure monitoring (ABPM). HRV parameters of ESRD patients and HCs, and the correlation of HRV parameters with cardiovascular screening methods were observed. All HRV parameters were significantly decreased in ESRD patients compared to HCs (P < 0.001). In the correlation analysis between TTE results and HRV parameters, 24-h standard deviation of all N-N intervals (24SDNN), 24-h standard deviation of sequential 5-min N-N interval means (24DANN) and Low Frequency Power/High Frequency Power (LF/HF) ratio showed negative correlations with E/e', LAVI and TR velocity which are representative indices for the diastolic function of the heart (P < 0.05). HRV parameters showed negative correlations with baPWV, CCS, and 24-h ABPM results as well (P < 0.05). Hemoglobin and serum albumin showed positive correlations with HRV parameters, and glucose, BUN, creatinine, and iPTH levels showed negative correlations (P < 0.05).

CONCLUSION

Continuous HRV monitoring may be a useful tool for the evaluation of CAN in ESRD.

Effect of dietary sodium restriction on blood pressure in type 2 diabetes: A meta-analysis of randomized controlled trials

AIMS

Although current guidelines recommend reduction of salt intake in patients with diabetes, the benefits of reducing salt intake in people with type 2 diabetes mellitus (T2DM) lack clear evidence. Therefore, we performed a meta-analysis of available randomized controlled trials (RCTs) of sodium restriction and blood pressure (BP) in patients with T2DM.

DATA SYNTHESIS

We performed a systematic search of the online databases that evaluated the effect of dietary sodium restriction on BP in patients with T2DM. Sodium intake was expressed by 24 h urinary sodium excretion (UNaV). Q statistics and I² were used to explore between-study heterogeneity. A random-effects model was used in the presence of significant heterogeneity; otherwise, a fixed-effects model was applied. Eight RCTs with 10 trials (7 cross-over and 3 parallel designs) were included in the meta-analysis. Compared with ordinary sodium intake, dietary sodium restriction significantly decreased UNaV (weighted mean difference, WMD: -38.430 mmol/24 h; 95% CI: -41.665 mmol/24 h to -35.194 mmol/24 h). Sodium restriction significantly lowered systolic BP (WMD: -5.574 mm Hg; 95% CI: -8.314 to -2.834 mm Hg; I² = 0.0%) and diastolic BP (WMD: -1.675 mm Hg; 95% CI: -3.199 to -0.150 mm Hg; I² = 0.0%) with low heterogeneity among the studies. No publication bias was found from Begg's and Egger's tests.

CONCLUSIONS

Sodium restriction significantly reduces SBP and DBP in patients with T2DM.

Infrainguinal bypass under triple nerve block in patients with severely compromised left ventricular ejection fraction and chronic limb-threatening ischemia

A severely compromised left ventricular ejection fraction (LVEF) is a major limitation for lower extremity bypass reconstruction both under general anesthesia or neuraxial anesthesia (NA). A series of eight infrainguinal bypass procedures were performed under peripheral nerve block in five patients (three males and two females; median age, 67 years) with chronic limb-threatening ischemia and a preoperative LVEF of 35% or less (median, 27%; range, 20%-35%). There were no conversions to neuraxial anesthesia/general anesthesia or early postoperative complications. This study showed that open infrainguinal reconstructions can be performed safely under peripheral nerve blockade in this vulnerable category of patients.

Effect of exercise-heat acclimation on cardiac autonomic modulation in type 2 diabetes: a pilot study

The effects of exercise-heat acclimation on heart rate variability (HRV) in individuals with type 2 diabetes (T2D) remains unclear. We assessed electrocardiogram recordings during exercise-heat stress in middle-aged-to-older individuals (50-70 years) with (n = 6) and without (control; n = 8;) T2D, before and after 7 days of exercise-heat acclimation. Exercising heart rate was reduced (control, -9 ± 5 bpm; T2D, -14 ± 9 bpm) yet HRV was not significantly different. Given the negative correlations between diminished HRV and cardiac risk observed in the scientific literature, further research is warranted. Novelty: Our observations indicate that 7 days exercise-heat acclimation may not effectively attenuate the deviation toward reduced overall HRV and unfavourable cardiac autonomic modulation in individuals with T2D.

Delayed orthostatic hypotension

Delayed orthostatic hypotension is a fall in blood pressure beyond 3 min of standing or upright tilt table testing. The prevalence, clinical features and pathophysiology are reviewed. To date, there is little data to support a standardized or recommended treatment. However, the 10-year mortality rates of individuals with delayed orthostatic hypotension are approximately 50%. Despite the fact that delayed orthostatic hypotension carries the same symptoms, risks and high mortality rate as classical orthostatic hypotension, but is under-recognized. The frequency with which delayed orthostatic hypotension develops into classical orthostatic hypotension, the high associated mortality rates and risk of development of the neurodegenerative disorders classified as alpha-synucleinopathies underscores the need for further study of this condition.

Cardiac autonomic modulation in type 1 diabetes during exercise-heat stress

AIMS

Cardiac autonomic modulation, as assessed by heart rate variability (HRV), is independently attenuated by both type 1 diabetes (T1D) and exercise-heat stress, although their combined effects remain unclear. We therefore assessed HRV during exercise-heat stress in young individuals (18-37 years) with (n = 14) and without type 1 diabetes (n = 14).

METHODS

Participants completed 30-min seated rest and three, 30-min bouts of semi-recumbent cycling at light, moderate, and vigorous metabolic heat productions (200, 250, 300 W/m², respectively), each followed by 30-min recovery. Body core temperature (T_core) and electrocardiogram were recorded throughout and analyzed during the final 5-min of rest and each exercise period.

RESULTS

Relative to baseline, T_core was increased in both groups, albeit to a greater extent in type 1 diabetes during vigorous exercise (T1D, 1.1 ± 0.3 °C; control, 0.8 ± 0.3 °C; P < 0.05). Overall HRV (as reflected by entropy) was attenuated throughout exercise relative to baseline in both groups, with the magnitude of the reduction greater in type 1 diabetes during vigorous exercise (T1D, - 108%; control, - 70%; P < 0.05).

CONCLUSIONS

Given the negative correlations between decreased HRV and cardiac risk, our novel observations indicate that vigorous exercise in hot environments may pose a health concern for individuals with type 1 diabetes.

Potency of inhibitors depends upon the accessibility of their aromatic rings within the hydrophobic specificity pocket: a novel avenue for future aldose reductase inhibitor design

Communicated by Ramaswamy H. Sarma.

The hemodynamic and pain impact of peripheral nerve block versus spinal anesthesia in diabetic patients undergoing diabetic foot surgery

PURPOSE

Comparison of hemodynamic profiles and pain scores in diabetic patients undergoing diabetic foot surgery receiving peripheral nerve block (PNB) or spinal anesthesia [subarachnoid block (SAB)].

METHODS

This was a prospective, randomised controlled trial. We recruited diabetic patients aged > 18 years, American Society of Anesthesiologists class II-III, who were scheduled for unilateral diabetic foot surgery below the knee. All patients were assessed for autonomic dysfunction using the Survey of Autonomic Symptoms score. Participants were randomly assigned to receive either PNB or SAB for the surgery. Hemodynamic data, including usage of vasopressors, were recorded at 5-min intervals for up to 1 h after the induction of anesthesia. Pain scores were recorded postoperatively, and follow-up was done via telephone 6 months later.

RESULTS

Compared to the PNB group, the SAB group had a larger number of patients with significant hypotension (14 vs. 1; p = 0.001) and more patients who required vasopressor boluses (6 vs. 0 patients). Compared to SAB group, the patients in the PNB group had a longer postoperative pain-free duration (9 vs. 4.54 h; p = 0.002) and lower pain scores 1 day after surgery (3.63 vs. 4.69; p = 0.01).

CONCLUSION

Peripheral nerve block should be considered, whenever possible, as the first option of anesthesia for lower limb surgery in diabetic patients as it provides hemodynamic stability and superior postoperative pain control compared to SAB.

TRIAL REGISTRATION

Clinical trial registry: ClinicalTrials.gov. ID NCT02727348.

The Effect of High-Intensity Interval Training on Physical Parameters, Metabolomic Indexes and Serum Ficolin-3 Levels in Patients with Prediabetes and Type 2 Diabetes

BACKGROUND

Exercise benefits people with abnormal glucose metabolism, and serum ficolin-3 levels have been reported to be associated with diabetes. However, no relevant study has discussed the relationship between high-intensity interval training (HIIT) and ficolin-3 in a Chinese population.

OBJECTIVE

To compare the effect of HIIT and moderate-intensity continuous training (MICT) on blood pressure, glucose control, the lipid profile and the serum ficolin-3 level in patients with prediabetes and type 2 diabetes (T2D).

METHODS

We recruited 145 patients with prediabetes and 196 T2D patients from March to June 2018. All participants were randomly grouped into HIIT and MICT groups. HIIT consisted of progressing to twelve 1-min bouts at 90% maximal aerobic capacity (1 min recovery), and MICT consisted of progressing to 20 min at 65% maximal aerobic capacity. ˙VO₂peak, body composition, blood pressure, glucose, the lipid profile and the serum ficolin-3 level were measured before and after three weeks of training.

RESULTS

After 3 weeks of training, participants in both the HIIT and MICT groups had significantly lower SBP, BMI, waist circumference, % body fat, and serum levels of FPG, TC, TGs, UA and ficolin-3, as well as increased vital capacity and VOmax. Additionally, the patients in the HIIT group still had significantly lower levels of 2hPG and LDL-C, regardless of prediabetes or diabetes status. After comparing the differences in the variation in parameters between the HIIT and MICT groups, we found that HIIT could help patients with prediabetes or diabetes acquire better effects of treatment in regard to anthropometry, blood pressure, glucose control, UA and ficolin-3 levels than MICT. Finally, the patients in the HIIT group had a lower rate of loss to follow-up and a higher rate of session attendance.

CONCLUSIONS

Both HIIT and MICT were beneficial exercise strategies for health in patients with prediabetes or T2D. However, HIIT is a more time-efficient strategy and could lower the serum level of ficolin-3 in patients after 3 weeks of training.

Prevalence and Diagnosis of Diabetic Cardiovascular Autonomic Neuropathy in Beijing, China: A Retrospective Multicenter Clinical Study

Cardiovascular autonomic neuropathy (CAN) is a debilitating condition occurring among diabetic patients especially those with long duration of disease. Whereas incidences and treatment of CAN has been well described for Western populations, fewer studies have been conducted among the Chinese. This study, therefore, aimed to assess the prevalence of CAN among sampled Chinese diabetic patients. Accordingly, 2,048 participants with a history of type 1 diabetes mellitus (T1DM, 73) and type 2 diabetes mellitus (T2DM, 1975) were randomly sampled from 13 hospitals. Patients’ biodata were recorded, and autonomic nervous system function tests performed to aid in the preliminary diagnosis of CAN. The final CAN diagnosis was based on the Ewing’s test in which heart rate variation (HRV) values were evaluated through deep-breathing (DB), lying-to-standing (LS), and Valsalva (V) tests. Systolic blood pressure (SBP) variation values were also evaluated through LS. In the T1DM group, 61.6% patients were diagnosed with CAN and no differences were observed in the baseline and clinical data between this group and those without CAN (P > 0.05). In the T2DM group, 62.6% patients were diagnosed with CAN and statistically significant differences were found between the CAN and non- CAN group with regards to age, duration of diabetes, metformin treatment, retinopathy, and hypertension history (P < 0.05). The most common manifestations of CAN included weakness (28.6%), dizziness (23.4%), frequent urination (19.6%), upper body sweating (18.3%), and nocturia (15.9%). Additionally, duration of disease and age were independent risk factors for CAN in T1DM and T2DM, respectively. On diagnosis, a combination of the V test + LS test provided the highest sensitivity of detecting CAN among T1DM group (sensitivity = 97.6%, AUC = 0.887) while for T2DM category, DB test had the highest sensitivity (83.6%), and maximal AUC (0.856) was found with V test + DB test. The overall prevalence of diabetes with CAN in the study was up to 63%.

Clinical factors associated with the recovery of cardiovascular autonomic neuropathy in patients with type 2 diabetes mellitus

Background

Cardiovascular autonomic neuropathy (CAN) is a major cause of morbidity and mortality in diabetes patients. Although several risk factors for CAN progression have been established, whether CAN is reversible remains unclear and the clinical factors associated with CAN recovery have not been identified. This study aimed to determine clinical factors related to CAN recovery.

Methods

Type 2 diabetes patients with CAN but free of cardiovascular disease at baseline were enrolled and followed for 2–3 years in this retrospective longitudinal study. CAN was classified as early (one abnormal parasympathetic test), definite (two or more abnormal parasympathetic tests), severe (definite plus orthostatic hypotension), or atypical (early plus orthostatic hypotension or orthostatic hypotension alone) based on Ewing’s method. CAN recovery was classified as partial or complete: Partial recovery was defined as one-step improvement in CAN stage (early to normal, definite to early, or severe to definite), including the disappearance of only one abnormal result in any stage. Complete recovery was defined as normalization from definite or severe CAN.

Results

Among 759 subjects with CAN, 29.9% (n = 227) experienced CAN recovery, and 1.2% (n = 9) recovered completely. In a multivariate model, younger age (odds ratio [OR] per 5-year decrease 1.49; 95% confidence interval [CI] 1.25–1.78, P < 0.001), shorter duration of diabetes (OR per 5-year decrease 1.33; 95% CI 1.05–1.67, P = 0.016), presence of micro/macroalbuminuria (OR 0.34; 95% CI 0.15–0.78, P = 0.011), body weight reduction (OR per 1-kg decrease 1.11; 95% CI 1.02–1.21, P = 0.016), and HbA1c reduction (OR per 1% decrease 1.32; 95% CI 1.05–1.67, P = 0.019) were significantly associated with composite events of partial and complete CAN recovery. Age had the highest relative significance among the associated clinical factors. In addition, younger age was the only significant factor in complete CAN recovery.

Conclusions

Younger age was the most important factor in CAN recovery in subjects with type 2 diabetes, including recovery from the definite or severe stage. HbA1c reduction, body weight reduction, no concurrent micro/macroalbuminuria, and shorter duration of diabetes were also significantly associated with CAN recovery.

Electronic supplementary material

The online version of this article (10.1186/s12933-019-0830-4) contains supplementary material, which is available to authorized users.

Cystatin C Is an Important Biomarker for Cardiovascular Autonomic Dysfunction in Chinese Type 2 Diabetic Patients

BACKGROUND

Cardiovascular autonomic dysfunction is closely related to increased mortality in patients with diabetes. Previous studies have proved that cystatin C (CysC) is an important predictor of both peripheral neuropathy and cardiovascular events. However, whether CysC is also associated with cardiovascular autonomic dysfunction remains unclear. Therefore, the aim of this study was to investigate the relationship between CysC and cardiovascular autonomic dysfunction in type 2 diabetic patients without renal dysfunction.

METHODS

A total of 161 type 2 diabetic patients with normal serum creatinine (less than 133 μmol/l) and estimated glomerular filtration rate (eGFR) higher than 60 ml/min per 1.73 m² were recruited in our study. Cardiovascular autonomic dysfunction was determined by heart rate variability (HRV) measured by a 24-hour Holter monitor. Serum CysC was tested by particle-enhanced turbidimetric immunoassay, and subjects were divided into three groups based on the tertiles of CysC. Pearson correlation analysis was used to evaluate the association between different indexes, and the association of CysC with HRV indexes was assessed by multivariate linear regression analysis.

RESULTS

The HRV parameters were lower in the group with the highest CysC concentration than in the groups with lower levels of CysC (P < 0.05). Pearson correlation analysis showed a negative relationship between CysC and the HRV parameters, including SDNN (r = -0.31, P < 0.001), SDANN (r = -0.25, P = 0.002), and logLF (r = -0.18, P = 0.023). Furthermore, multivariate linear regression analysis revealed that CysC was independently correlated with SDNN (β = -24.11, P = 0.015) and SDANN (β = -19.88, P = 0.047) after adjusting for the confounding factors of gender, age, blood pressure, body mass index, eGFR, and hemoglobin A1c.

CONCLUSIONS

Serum CysC levels are associated with cardiovascular autonomic dysfunction; furthermore, CysC may be a reliable and convenient biomarker for detecting cardiovascular autonomic dysfunction.

Association of glucose and blood pressure variability on oxidative stress in patients with type 2 diabetes mellitus and hypertension: a cross-sectional study

BACKGROUND

The present study evaluated the effects of glucose and blood pressure (BP) variability on oxidative stress in patients with type 2 diabetes mellitus (T2DM) and hypertension.

METHODS

A total of 60 inpatients with T2DM underwent continuous glucose monitoring (CGM) and ambulatory BP monitoring (ABPM). Oxidative stress was estimated using the diacron-reactive oxygen metabolites (d-ROMs) test. Glucose variability, mean glucose level, percentage coefficient of variation for glucose, mean amplitude of glycemic excursions (MAGE), and area under the postprandial plasma glucose curve were determined through CGM. BP variability was assessed by measuring average BP, standard deviation (SD) of systolic and diastolic BP, and coefficient of variation (CV) of systolic and diastolic BP during daytime and nighttime ABPM.

RESULTS

Participants had a mean age of 64.5 ± 13.3 years with the duration of the disease 13.9 ± 12.4 years and HbA1c of 8.5 ± 1.2%. Univariate analysis showed that MAGE, nighttime SDs of systolic and diastolic BP, and nighttime CV of systolic BP were significantly correlated with d-ROMs. Further, stepwise multiple regression analysis identified MAGE, nighttime SD and CV of diastolic BP, estimated glomerular filtration rate, and smoking as independent contributors to d-ROMs.

CONCLUSIONS

Oxidative stress was associated with daily glucose and nighttime diastolic BP variability in patients with T2DM and hypertension.Trial registration UMIN Clinical Trial Registry UMIN000035615, Registered January 22, 2019-retrospectively registered.

Progression of cardiovascular autonomic neuropathy and cardiovascular disease in type 2 diabetes

BACKGROUND

To examine whether the progression rate of cardiovascular autonomic neuropathy (CAN) stage is an independent predictive factor for cardiovascular disease (CVD) in type 2 diabetes.

METHODS

Standardized cardiovascular autonomic reflex tests (CARTs) using traditional Ewing method were performed at baseline. The follow-up CARTs was recommended once every two years. We estimated the primary CVD endpoint, defined as coronary artery disease and ischemic stroke. The association between the progression rate of CAN stage and CVD was examined using time-dependent Cox proportional hazard models.

RESULTS

At baseline, 578 patients completed follow-up CARTs; the cohort comprised 329 women (56.9%) with a mean age of 58.3 ± 10.3 years and a mean diabetes duration of 10.1 ± 6.2 years. One hundred and seventy-six patients (30.4%) developed CAN progression between baseline and follow-up CARTs. In the multivariable Cox proportional hazards regression analysis, patients with CAN progression demonstrated a 3.32 times higher risk (95% confidence interval, CI 1.81-6.14, P < 0.001) of CVD than those without CAN progression. Patients who experienced CAN progression from the normal to definite stage had the greatest risk of CVD compared to other patients (hazard ratio 4.91, 95% CI 2.05-11.77, P for trend = 0.001).

CONCLUSIONS

CAN stage progression was associated with an increased risk of CVD in this type 2 diabetes cohort. Patients with rapid CAN progression had the greatest risk of CVD. Thus, regular screening and risk management of CAN progression is necessary to prevent CVD.

AMERICAN ASSOCIATION OF CLINICAL ENDOCRINOLOGISTS AND AMERICAN COLLEGE OF ENDOCRINOLOGY POSITION STATEMENT ON TESTING FOR AUTONOMIC AND SOMATIC NERVE DYSFUNCTION

This document represents the official position of the American Association of Clinical Endocrinologists and the American College of Endocrinology. Where there were no randomized controlled trials or specific U.S. FDA labeling for issues in clinical practice, the participating clinical experts utilized their judgment and experience. Every effort was made to achieve consensus among the committee members. Position statements are meant to provide guidance, but they are not to be considered prescriptive for any individual patient and cannot replace the judgment of a clinician.

Cardiac autonomic neuropathy: Risk factors, diagnosis and treatment

Cardiac autonomic neuropathy (CAN) is a serious complication of diabetes mellitus (DM) that is strongly associated with approximately five-fold increased risk of cardiovascular mortality. CAN manifests in a spectrum of things, ranging from resting tachycardia and fixed heart rate (HR) to development of "silent" myocardial infarction. Clinical correlates or risk markers for CAN are age, DM duration, glycemic control, hypertension, and dyslipidemia (DLP), development of other microvascular complications. Established risk factors for CAN are poor glycemic control in type 1 DM and a combination of hypertension, DLP, obesity, and unsatisfactory glycemic control in type 2 DM. Symptomatic manifestations of CAN include sinus tachycardia, exercise intolerance, orthostatic hypotension (OH), abnormal blood pressure (BP) regulation, dizziness, presyncope and syncope, intraoperative cardiovascular instability, asymptomatic myocardial ischemia and infarction. Methods of CAN assessment in clinical practice include assessment of symptoms and signs, cardiovascular reflex tests based on HR and BP, short-term electrocardiography (ECG), QT interval prolongation, HR variability (24 h, classic 24 h Holter ECG), ambulatory BP monitoring, HR turbulence, baroreflex sensitivity, muscle sympathetic nerve activity, catecholamine assessment and cardiovascular sympathetic tests, heart sympathetic imaging. Although it is common complication, the significance of CAN has not been fully appreciated and there are no unified treatment algorithms for today. Treatment is based on early diagnosis, life style changes, optimization of glycemic control and management of cardiovascular risk factors. Pathogenetic treatment of CAN includes: Balanced diet and physical activity; optimization of glycemic control; treatment of DLP; antioxidants, first of all α-lipoic acid (ALA), aldose reductase inhibitors, acetyl-L-carnitine; vitamins, first of all fat-soluble vitamin B1; correction of vascular endothelial dysfunction; prevention and treatment of thrombosis; in severe cases-treatment of OH. The promising methods include prescription of prostacyclin analogues, thromboxane A2 blockers and drugs that contribute into strengthening and/or normalization of Na+, K+-ATPase (phosphodiesterase inhibitor), ALA, dihomo-γ-linolenic acid (DGLA), ω-3 polyunsaturated fatty acids (ω-3 PUFAs), and the simultaneous prescription of ALA, ω-3 PUFAs and DGLA, but the future investigations are needed. Development of OH is associated with severe or advanced CAN and prescription of nonpharmacological and pharmacological, in the foreground midodrine and fludrocortisone acetate, treatment methods are necessary.

High-Intensity Interval Training Is Equivalent to Moderate-Intensity Continuous Training for Short- and Medium-Term Outcomes of Glucose Control, Cardiometabolic Risk, and Microvascular Complication Markers in Men With Type 2 Diabetes

We sought to determine the efficacy of 12 weeks high-intensity interval training (HIIT), compared to moderate-intensity continuous training (MICT) on glucose control, cardiometabolic risk and microvascular complication markers in men living with type 2 diabetes (T2D). Both modalities were combined with resistance training (RT). Additionally, the study aimed to determine the medium-term durability of effects. After a 12-week, thrice weekly, training intervention incorporating either MICT+RT (n = 11) or HIIT+RT (n = 12), the study concluded with a 6-month follow-up analysis. The middle-aged study participants were obese, had moderate duration T2D and were taking multiple medications including insulin, statins and beta-blockers. Participants, randomized via the method of minimization, performed MICT (progressing to 26-min at 55% maximum estimated workload [eWLmax]) or HIIT (progressing to two variations in which twelve 1-min bouts at 95% eWLmax interspersed with 1-min recovery bouts, alternated with eight 30-s bouts at 120% eWLmax interspersed with 2:15 min recovery bouts) under supervision at an exercise physiology facility. To account for fixed and random effects within the study sample, mixed-effect models were used to determine the significance of change following the intervention and follow-up phases and to evaluate group^*time interactions. Beyond improvements in aerobic capacity (P < 0.001) for both groups, both training modalities elicited similar group^*time interactions (P > 0.05) while experiencing benefits for glycated hemoglobin (HbA1c; P = 0.01), subcutaneous adiposity (P < 0.001), and heart rate variability (P = 0.02) during the 12-week intervention. Adiposity (P < 0.001) and aerobic capacity (P < 0.001) were significantly maintained in both groups at the 6-month follow-up. In addition, during the intervention, participants in both MICT+RT and HIIT+RT experienced favorable reductions in their medication usage. The study reported the inter-individual variability of change within both groups, the exaggerated acute physiological responses (using exercise termination indicators) that occurred during the interventions as well as the incidence of precautionary respite afforded in such a study sample. To reduce hyperglycaemia, and prevent further deterioration of cardiometabolic risk and microvascular complication markers (in both the short- and medium-term), future strategies that integrate the adoption and maintenance of physical activity as a cornerstone in the treatment of T2M for men should (cognisant of appropriate supervision) include either structured MICT+RT, or HIIT+RT. Clinical Trials Registration Number: ACTRN12617000582358 http://www.anzctr.org.au/default.aspx.

Combination of Ewing test, heart rate variability, and heart rate turbulence analysis for early diagnosis of diabetic cardiac autonomic neuropathy

The aim of this study was to compare and analyze Ewing test, heart rate variability (HRV), and heart rate turbulence (HRT) in the diagnosis of cardiac autonomic neuropathy (CAN) in diabetic patients.Ninety diabetic patients (age 18-78) and 20 nondiabetic control subjects were studied. Standard Ewing test and 24-hour Holter was performed in all participants to evaluate CAN. Patients with Ewing score ≥2 were classified as CAN+.The rate of CAN+ in diabetic patients [44.4% (40/90)] was higher than that in the controls [5% (1/20)] (P < .05). Using the HRV analysis and HRT analysis, rates of CAN+ in diabetic patients were 56.67% (51/90) and 52.22% (47/90), respectively. SD of all normal-to-normal (NN) intervals (SDNN), SD of the average NN intervals calculated over 5-minute periods of the entire recording (SDANN), low frequency power (LF), and turbulence slope (TS) were significantly correlated negatively with Ewing scores. TS (r = -0.68, P < .05) and SDNN (r = -0.58, P < .05) had the strongest correlation with Ewing scores among relevant factors. Combining TS with SDNN as diagnostic criteria for CAN, the diagnostic sensitivity can be increased to 98%.Parameters used for evaluating parasympathetic functions in Ewing test, HR variability, and HR turbulence were found to significantly decrease in CAN+ group. The combination of SDNN and TS showed greater diagnostic value than Ewing test, HRV analysis, or HRT analysis alone.

General Anesthesia Imposes Negative Effects on Heart Rate and Blood Pressure Regulation in Patients With a History of Head and Neck Radiation Therapy

BACKGROUND

Head and neck radiation therapy (HNRT) impairs baroreflex sensitivity, and it may potentiate the effects of anesthetics on heart rate (HR) and blood pressure (BP) regulation. Currently, the impacts of HNRT on HR and BP under anesthesia remain unclear.

METHODS

In this study, 472 patients with primary oral cavity or oropharyngeal cancer at all stages were examined. Half of the patients underwent HNRT plus surgery. The other half underwent surgery only and was matched with the treatment patients according to age, sex, and body mass index at a 1:1 ratio. The HRs and BPs in the 2 groups during anesthetic induction, skin incision, and emergence were compared retrospectively. A multivariable model of repeated measures with unstructured covariance structure was used to examine the associations of HNRT with intraoperative HRs and BPs after adjusting for baseline HR and BP, time, use of β-blockers, history of chemotherapy, and American Society of Anesthesiologists physical status score. BPs and HRs were collected every 5 minutes. The baseline HR and BP measurements were not included in the outcome vector and were only used as adjustment for baselines.

RESULTS

Compared with corresponding baseline values in controls, the baseline HR was significantly higher (P = .0012) and the baseline systolic BP was lower (P < .0001) in the treatment group. The baseline diastolic BP levels did not differ significantly (P = .6411). Fewer patients receiving HNRT than controls took β-blockers daily (17% vs 28%; P = .0041). Comparing the corresponding values in control and treatment groups, multivariable analysis revealed significant associations of HNRT with decreases in HR during anesthesia induction (-2.21 [95% confidence interval {CI}, -4.42 to -0.01]; P = .0492) and skin incision (-2.66 [95% CI, -5.16 to -0.16]; P = .0373) and of HNRT with decreases in systolic BP during anesthesia induction (-6.88 [95% CI, -10.99 to -2.78]; P = .0011) and skin incision (-15.87 [95% CI, -20.45 to -11.29]; P < .001). However, we observed a significant association of HNRT with decrease in diastolic BP only during skin incision (-6.50 [95% CI, -9.47 to -3.53]; P < .0001).

CONCLUSIONS

The significant finding in the study was that general anesthesia imposed a negative chronotropic effect on HR in the group given HNRT. Therefore, one should be watchful for bradycardia in these patients; particularly those with low BPs. Their hemodynamics may rapidly progress into an unstable status when bradycardia and hypotension develop altogether.

Impact of type 2 diabetes on cardiorespiratory function and exercise performance

The aim of this study was to examine the impact of well‐controlled uncomplicated type 2 diabetes (T2D) on exercise performance. Ten obese sedentary men with T2D and nine control participants without diabetes matched for age, sex, and body mass index were recruited. Anthropometric characteristics, blood samples, resting cardiac, and pulmonary functions and maximal oxygen uptake (VO_2max) and ventilatory threshold were measured on a first visit. On the four subsequent visits, participants (diabetics: n = 6; controls: n = 7) performed step transitions (6 min) of moderate‐intensity exercise on an upright cycle ergometer from unloaded pedaling to 80% of ventilatory threshold. VO₂ (τVO₂) and HR (τHR) kinetics were characterized with a mono‐exponential model. VO_2max (27.0 ± 3.4 vs. 26.7 ± 5.0 mL kg⁻¹ min⁻¹; P = 0.85), τVO₂ (43 ± 6 vs. 43 ± 10 sec; P = 0.73), and τHR (42 ± 17 vs. 43 ± 13 sec; P = 0.94) were similar between diabetics and controls respectively. The remaining variables were also similar between groups, with the exception of lower maximal systolic blood pressure in diabetics (P = 0.047). These results suggest that well‐controlled T2D is not associated with a reduction in VO_2max or slower τVO₂ and τHR.

Cardiac autonomic neuropathy in patients with diabetes mellitus: current perspectives

Cardiac autonomic neuropathy (CAN) is a common and often-underdiagnosed complication of diabetes mellitus (DM). CAN is associated with increased mortality, cardiovascular disease, chronic kidney disease, and morbidity in patients with DM, but despite these significant consequences CAN often remains undiagnosed for a prolonged period. This is commonly due to the disease being asymptomatic until the later stages, as well as a lack of easily available screening strategies. In this article, we review the latest developments in the epidemiology, pathogenesis, diagnosis, consequences, and treatments of CAN in patients with DM.

Association of SUDOSCAN Values with Vibration Perception Threshold in Chinese Patients with Type 2 Diabetes Mellitus

AIMS/INTRODUCTION

SUDOSCAN has been proved to be an efficient method in detecting diabetic microvascular complications. In this study, we determine to detect the possible relationship between vibration perception threshold (VPT) and cardiac autonomic neuropathy (CAN) values produced by SUDOSCAN.

MATERIALS AND METHODS

A total of 920 Chinese patients with T2DM were enrolled in the study. Spearman correlation analysis and multivariate regression analysis were performed to determine the relation between CAN and VPT values. Mean VPT values across the CAN value tertiles were analyzed stratified by HbA1c status.

RESULTS

In the study, we discovered a relatively high correlation between CAN value and both VPT values from dorsal feet and toes. Multivariate regression analyses also showed a significant relation between VPT and CAN values after adjusting all covariates. The mean value of VPT decreased across the SUDOSCAN-CAN value quartiles in both groups, and it was higher in patients with HbA1C > 9% than in patients with HbA1C < 9% across all quartiles of the SUDOSCAN-CAN except for the VPT mean in the low quartile of the SUDOSCAN-CAN value.

CONCLUSIONS

All these results suggested that SUDOSCAN-CAN result was associated with VPT value which indicated a probable link between VPT value and cardiovascular autonomic dysfunction.

The U-shaped relationship between fibroblast growth factor 21 and microvascular complication in type 2 diabetes mellitus

AIMS

The aim of this study was to investigate the relationship between serum FGF21 level and all microvascular complication including cardiac autonomic neuropathy (CAN) in patients with type 2 diabetes mellitus (T2DM).

METHODS

A total 227 T2DM patients were enrolled and serum FGF21 levels were assessed. Diabetic retinopathy, nephropathy, peripheral neuropathy (DPN), and CAN were evaluated.

RESULTS

The prevalence of retinopathy and nephropathy among the FGF21 tertiles was significantly different (p=0.001, p=0.006, respectively), whereas no difference was found in the prevalence of DPN and CAN. In multivariate analysis, the odds ratio (OR) for the presence of retinopathy was 0.08 for the FGF21 second tertile when compared with the first tertile (p=0.029). OR of retinopathy in third tertile group was lower than first tertile and higher than second tertile, but statistically insignificant. Crude OR for nephropathy was 0.34 for the second FGF21 tertile, when compared with the first tertile (p=0.015). However, FGF21 level was not significantly associated with nephropathy after multivariable adjustment.

CONCLUSIONS

In the present study, there was no association between diabetic nephropathy, DPN, and CAN and serum FGF21 levels. However, we found a U-shaped relationship between both lower and higher serum FGF21 levels and diabetic retinopathy. This result suggests that the very low serum FGF21 level itself may associate with diabetic retinopathy and also relatively elevated serum FGF21 level may be a compensatory increase to protect against microvascular injury.

Vitamin D Insufficiency is Associated with Reduced Parasympathetic Nerve Fiber Function in Type 2 Diabetes

OBJECTIVE

Vitamin D insufficiency is prevalent in subjects with type 2 diabetes mellitus (T2DM) and is associated with peripheral neuropathy. However, there are little data regarding vitamin D status in patients with cardiovascular autonomic neuropathy. Our objective was to evaluate the association of cardiovascular autonomic function, 25-hydroxyvitamin D (25[OH]D) insufficiency (i.e., levels <30 ng/mL), and multiple metabolic parameters in subjects with T2DM.

METHODS

We examined 50 individuals with T2DM. Cardiovascular autonomic function (i.e., parasympathetic function) was assessed by RR-variation during deep breathing (i.e., mean circular resultant [MCR] and expiration/inspiration [E/I] ratio). Metabolic parameters included measures of adiposity, glycemic control, insulin resistance, calcium metabolism, and 25(OH)D.

RESULTS

Participants with 25(OH)D insufficiency (n = 26) were younger (66 ± 9 vs. 60 ± 10 years, P<.05), more insulin resistant, had a higher body mass index (BMI) and lower adiponectin levels. The MCR (39.5 ± 26.3 vs. 27.6 ± 17.2, P<.01) and E/I ratio (1.21 ± 0.17 vs. 1.15 ± 0.09, P<.01) were lower for those with 25(OH)D insufficiency after controlling for age. A stepwise selection procedure regressing MCR and E/I ratio on a number of metabolic parameters resulted in a model identifying age and 25(OH)D insufficiency as significant determinants for both measures. The interaction of age x 25(OH)D insufficiency was also included (MCR model, R2 = 0.491, P<.001; E/I ratio, R2 = 0.455, P<.001). Neither glycemic control nor other metabolic parameters were selected.

CONCLUSION

Our results suggest that 25(OH)D insufficiency is associated with reduced parasympathetic function, with a stronger association in younger persons with T2DM. Studies are needed to determine if vitamin D supplementation into the sufficient range could prevent or delay the onset of cardiovascular autonomic dysfunction.

Assessment of the cardiac autonomic neuropathy among the known diabetics and age-matched controls using noninvasive cardiovascular reflex tests in a South-Indian population: A case-control study

AIM

Diabetes mellitus is a chronic condition characterized by hyperglycemia. The objective of the study was to estimate the prevalence of cardiac autonomic neuropathy in a rural area of South India, among the known diabetics after comparing them with the age-matched healthy controls, utilizing noninvasive cardiac autonomic neuropathy reflex tests.

MATERIALS AND METHODS

A case-control study was conducted for 4 months (October 2014 to January 2015) at an Urban Health and Training Center (UHTC) of a Medical College located in Kancheepuram district, Tamil Nadu. The study was conducted among 126 diagnosed Type 2 diabetes patients and in 152 age- and sex-matched healthy controls to ensure comparability between the cases and controls and, thus, reduce variability due to demographic variables. All the study subjects (cases and controls) were selected from the patients attending UHTC during the study duration, provided they satisfied the inclusion and exclusion criteria. Study participants were subjected to undergo noninvasive cardiac autonomic neuropathy reflex tests. The associations were tested using paired t-test for the continuous (mean ± standard deviation) variables.

RESULTS

The overall prevalence of cardiac autonomic neuropathy among diabetic patients was found to be as 53.2% (67/126). On further classification, positive (abnormal) results were obtained in 56 (sympathetic - 44.4%) and 51 (parasympathetic - 40.5%) diabetic cases. Overall, heart rate variation during deep breathing was found to be the most sensitive test to detect parasympathetic autonomic neuropathy while the diastolic blood pressure response to sustained handgrip exercise was the most sensitive method to detect sympathetic neuropathy dysfunction.

CONCLUSION

The overall prevalence of cardiac autonomic neuropathy among diabetic patients was found to be as 53.2%. Even though cardiac autonomic neuropathy can be detected by various invasive tests, noninvasive tests remain a key tool to detect it in the remote settings in a cost-effective and user-friendly manner without making people visit higher centers.

Heart Rate Variability in Diabetes Patients

Diabetes mellitus can cause cardiovascular autonomic neuropathy and is associated with increased cardiovascular deaths. We investigated cardiovascular autonomic neuropathy in diabetics and healthy controls by analysis of heart rate variability. Thirty-one diabetics and 30 age- and sex-matched controls were included. In the time domain we measured the mean R-R interval (NN), the standard deviation of the R-R interval index (SDNN), the standard deviation of the 5-min R - R interval mean (SDANN), the root mean square of successive R - R interval differences (RMSSD) and the percentage of beats with a consecutive R - R interval difference > 50 ms (pNN50). In the frequency domain we measured high-frequency power (HF), low-frequency power (LF) and the LF/HF ratio. Diabetes patients had lower values for time-domain and frequency-domain parameters than controls. Most heart rate variability parameters were lower in diabetes patients with chronic complications than in those without chronic complications.

Effect of One-Week Salt Restriction on Blood Pressure Variability in Hypertensive Patients with Type 2 Diabetes

Background

Increased short-term blood pressure (BP) variability on 24-hour ambulatory BP monitoring (ABPM) is known to be a risk factor for cardiovascular events. However, very few studies have evaluated the effect of salt restriction on BP variability particularly in hypertensive patients with type 2 diabetes. This study aimed to investigate the effect of salt restriction on systolic BP (SBP) variability.

Methods and Results

10 hypertensive patients with type 2 diabetes and not receiving antihypertensive agents were enrolled in the study. After admission, all patients received a salt-restricted diet and appropriate anti-diabetic treatments and were followed up for 7 consecutive days using ABPM. After the 7-day treatment, the median [interquartile range (IQR)] coefficient of variation (CV) for diurnal SBP variability changed from day 1 to day 7–13.0 [10.8 to 16.8] % to 13.3 [9.1 to 18.9] % (P = 0.959)—and the median [IQR] change between days 1 and 7 was -0.3 [-3.2 to 2.9] %. In addition, CV for BP variability and circadian rhythm of BP varied greatly on a day-by-day basis for 7 days, compared to mean BP values. Interestingly, increased SBP variability was associated with greater day-by-day changes in circadian rhythm of BP.

Conclusions

Salt restriction during 7-day hospitalization led to a -0.3 [-3.2 to 2.9] (median [IQR]) % change from baseline in CV for diurnal SBP variability in 10 hypertensive patients with type 2 diabetes not receiving antihypertensive agents.

Trial Registration

UMIN Clinical Trials Registry UMIN000016243

SOD1 Overexpression Preserves Baroreflex Control of Heart Rate with an Increase of Aortic Depressor Nerve Function

Overproduction of reactive oxygen species (ROS), such as the superoxide radical (O₂^∙−), is associated with diseases which compromise cardiac autonomic function. Overexpression of SOD1 may offer protection against ROS damage to the cardiac autonomic nervous system, but reductions of O₂^∙− may interfere with normal cellular functions. We have selected the C57B6SJL-Tg (SOD1)2 Gur/J mouse as a model to determine whether SOD1 overexpression alters cardiac autonomic function, as measured by baroreflex sensitivity (BRS) and aortic depressor nerve (ADN) recordings, as well as evaluation of baseline heart rate (HR) and mean arterial pressure (MAP). Under isoflurane anesthesia, C57 wild-type and SOD1 mice were catheterized with an arterial pressure transducer and measurements of HR and MAP were taken. After establishing a baseline, hypotension and hypertension were induced by injection of sodium nitroprusside (SNP) and phenylephrine (PE), respectively, and ΔHR versus ΔMAP were recorded as a measure of baroreflex sensitivity (BRS). SNP and PE treatment were administered sequentially after a recovery period to measure arterial baroreceptor activation by recording aortic depressor nerve activity. Our findings show that overexpression of SOD1 in C57B6SJL-Tg (SOD1)2 Gur/J mouse preserved the normal HR, MAP, and BRS but enhanced aortic depressor nerve function.

Association of serum omentin levels with cardiac autonomic neuropathy in patients with type 2 diabetes mellitus: a hospital-based study

Background

Whereas a few studies have reported associations of serum omentin levels with subclinical atherosclerosis in patients with diabetes, little information is available with respect to the associations of serum omentin levels and diabetic microvascular complications. The aim of this study was to investigate the relationships of serum omentin levels and vascular complications including cardiac autonomic neuropathy (CAN) in patients with type 2 diabetes mellitus (T2DM).

Methods

We recruited 97 patients who evaluated complications of diabetes. CAN was assessed by five standard cardiovascular reflex tests according to Ewing’s protocol. Diabetic nephropathy (DN), retinopathy (DR), and peripheral neuropathy (DPN) were evaluated. Serum omentin levels were assessed by ELISA. Atherosclerotic burden was evaluated by measuring the brachial-ankle pulse wave velocity (baPWV) and ankle brachial index (ABI).

Results

The prevalence of CAN increased borderline significantly across the omentin tertiles (p = 0.05) and CAN point increased significantly and progressively across the omentin tertiles (p = 0.013). The prevalence of other microvascular complications (DPN, DN, and DR) did not differ among omentin tertiles. The mean levels of baPWV also increased significantly and progressively across the omentin tertiles (p = 0.002). Serum omentin levels were significantly positively correlated with CAN point (p = 0.004) and borderline significantly correlated with baPWV (p = 0.05) after multivariate adjustment. Regarding linear regression analysis for CAN point, univariate regression analysis demonstrated that CAN point associated with omentin, diastolic blood pressure (DBP) and hsCRP. Multiple regression analysis revealed that omentin levels, together DBP and baPWV correlated with CAN point. This present study suggests that serum omentin levels may be independently associate with CAN in patients with T2DM.

Dynamics of heart rate variability in patients with type 2 diabetes mellitus during spinal anaesthesia: prospective observational study

Background

Little is known about the changes in autonomic function during spinal anaesthesia in type 2 diabetic patients. The purpose of the study was to assess the influence of spinal anaesthesia on the heart rate variability in type 2 diabetic patients according to the glycated hemoglobin (HbA_1c) level.

Methods

Sixty-six patients who were scheduled for elective orthostatic lower limb surgery were assigned to three groups (n = 22, each) according to HbA_1c; controlled diabetes mellitus (HbA_1c < 7 %), uncontrolled diabetes mellitus (HbA_1c > 7 %) and the control group. The heart rate variability was measured 10 min before (T0), and at10 min (T1), 20 min (T2) and 30 min (T3) after spinal anaesthesia.

Results

Before spinal anaesthesia, total, low-and high-frequency power were significantly lower in the uncontrolled diabetec group than in other group (p < 0.05). During spinal anaesthesia, total, low- and high-frequency powers were did not change in the uncontrolled diabetec group while the low-frequency power in the controlled diabetec group was significantly depressed (p < 0.05). The ratio of low-to high-frequency was comparable among the groups, while it was reduced at T1-2 than at T0 in all the groups. The blood pressures were higher in the uncontrolled diabetec group than in the other groups.

Conclusions

Spinal anaesthesia had an influence on the cardiac autonomic modulation in controlled diabetec patients, but not in uncontrolled diabetec patients. There were no differences in all haemodynamic variables during an adequate level of spinal anaesthesia in controlled and uncontrolled type 2 DM.

Trial registration

ClinicalTrials.gov NCT02137057

Electronic supplementary material

The online version of this article (doi:10.1186/s12871-015-0125-6) contains supplementary material, which is available to authorized users.

Clinical implications of delayed orthostatic hypotension: A 10-year follow-up study

OBJECTIVE

To define the long-term outcome of delayed orthostatic hypotension (OH).

HYPOTHESIS

Delayed OH is an early and milder form of OH that progresses over time.

METHODS

We reviewed the medical records of 230 previously reported patients who completed autonomic testing at our center from January 1, 2002, through December 31, 2003. All available information on clinical diagnosis, mortality, medication use, and autonomic testing were extracted and included in the reported outcomes. Standard criteria were used to define OH and delayed OH.

RESULTS

Forty-eight individuals with delayed OH, 42 individuals with OH, and 75 controls had complete follow-up data. Fifty-four percent of individuals with delayed OH progressed to OH. Thirty-one percent of individuals with delayed OH developed an α-synucleinopathy. The 10-year mortality rate in individuals with delayed OH was 29%, in individuals with baseline OH was 64%, and in controls was 9%. The 10-year mortality of individuals who progressed to OH was 50%. Progression to OH was associated with developing an α-synucleinopathy, baseline diabetes, and abnormal baseline autonomic test results.

CONCLUSION

Delayed OH frequently progresses to OH with a high associated mortality.

The relationship between vitamin D status and cardiac autonomic neuropathy in patients with type 2 diabetes mellitus

OBJECTIVE

This study evaluates cardiac autonomic neuropathy and heart rate variability according to the vitamin D status in type 2 diabetes mellitus.

METHODS

A total of 163 patients were recruited. Cardiac autonomic neuropathy was assessed using five tests according to Ewing's protocol. The time and frequency domains of the heart rate variability were also evaluated. Patients were separated into three groups: vitamin D sufficient [25(OH)D ⩾ 20 ng/mL], vitamin D insufficient [10 ⩽ 25(OH)D < 20] and vitamin D deficiency [25(OH)D < 10] groups.

RESULTS

Both standard deviation of normal-to-normal RR intervals and square root of the average of the sum of the squares of the differences between adjacent NN intervals in the supine position were significantly lower in vitamin D deficient group. Low frequency/high frequency ratio in the upright position was significantly higher in the vitamin D deficient group. 25(OH)D levels are positively correlated with standard deviation of normal-to-normal RR intervals in the supine position. In multivariate logistic analysis, patients with vitamin D levels of 10 < 25(OH)D < 20 ng/mL showed borderline significantly lower cardiac autonomic neuropathy risk than those with 25(OH)D levels <10 ng/mL (odds ratio = 0.45 (0.23-1.01), p = 0.051).

CONCLUSION

Vitamin D deficiency was significantly correlated with heart rate variability parameters. However, there was only borderline significant association between vitamin D concentration and presence of cardiac autonomic neuropathy. Therefore, future studies are required to establish a relationship between vitamin D levels and cardiac autonomic neuropathy.

Exposure to Discrimination and Heart Rate Variability Reactivity to Acute Stress among Women with Diabetes

Exposure to racial discrimination has been linked to physiological reactivity. This study investigated self-reported exposure to racial discrimination and parasympathetic [high-frequency heart rate variability (HF-HRV)] and sympathetic (norepinephrine and cortisol) activity at baseline and then again after acute laboratory stress. Lifetime exposure to racial discrimination was measured with the Schedule of Racist Events scale. Thirty-two women (16 Black and 16 White) with type 2 diabetes performed a public speaking stressor. Beat-to-beat intervals were recorded on electrocardiograph recorders, and HF-HRV was calculated using spectral analysis and natural log transformed. Norepinephrine and cortisol were measured in blood. Higher discrimination predicted lower stressor HF-HRV, even after controlling for baseline HF-HRV. When race, age, A1c and baseline systolic blood pressure were also controlled, racial discrimination remained a significant independent predictor of stressor HF-HRV. There was no association between lifetime discrimination and sympathetic markers. In conclusion, preliminary data suggest that among women with type 2 diabetes mellitus (T2DM), exposure to racial discrimination is adversely associated with parasympathetic, but not sympathetic, reactivity.

Identifying Common Genetic Risk Factors of Diabetic Neuropathies

Type 2 diabetes mellitus (T2DM) is a global public health problem of epidemic proportions, with 60-70% of affected individuals suffering from associated neurovascular complications that act on multiple organ systems. The most common and clinically significant neuropathies of T2DM include uremic neuropathy, peripheral neuropathy, and cardiac autonomic neuropathy. These conditions seriously impact an individual's quality of life and significantly increase the risk of morbidity and mortality. Although advances in gene sequencing technologies have identified several genetic variants that may regulate the development and progression of T2DM, little is known about whether or not the variants are involved in disease progression and how these genetic variants are associated with diabetic neuropathy specifically. Significant missing heritability data and complex disease etiologies remain to be explained. This article is the first to provide a review of the genetic risk variants implicated in the diabetic neuropathies and to highlight potential commonalities. We thereby aim to contribute to the creation of a genetic-metabolic model that will help to elucidate the cause of diabetic neuropathies, evaluate a patient's risk profile, and ultimately facilitate preventative and targeted treatment for the individual.

Diabetic cardiac autonomic neuropathy: Do we have any treatment perspectives?

Cardiac autonomic neuropathy (CAN) is a serious and common complication of diabetes mellitus (DM). Despite its relationship to an increased risk of cardiovascular mortality and its association with multiple symptoms and impairments, the significance of CAN has not been fully appreciated. CAN among DM patients is characterized review the latest evidence and own data regarding the treatment and the treatment perspectives for diabetic CAN. Lifestyle modification, intensive glycemic control might prevent development or progression of CAN. Pathogenetic treatment of CAN includes: balanced diet and physical activity; optimization of glycemic control; treatment of dyslipoproteinemia; correction of metabolic abnormalities in myocardium; prevention and treatment of thrombosis; use of aldose reductase inhibitors; dihomo-γ-linolenic acid (DGLA), acetyl-L-carnitine, antioxidants, first of all α-lipoic acid (α-LA), use of long-chain ω-3 and ω-6 polyunsaturated fatty acids (ω-3 and ω-6 PUFAs), vasodilators, fat-soluble vitamin B₁, aminoguanidine; substitutive therapy of growth factors, in severe cases-treatment of orthostatic hypotension. The promising methods include research and use of tools that increase blood flow through the vasa vasorum, including prostacyclin analogues, thromboxane A₂ blockers and drugs that contribute into strengthening and/or normalization of Na⁺, K⁺-ATPase (phosphodiesterase inhibitor), α-LA, DGLA, ω-3 PUFAs, and the simultaneous prescription of α-LA, ω-3 PUFA and DGLA.

Heart Rate Turbulence and T-Wave Alternans in Patients with Coronary Artery Disease: The Influence of Diabetes

BACKGROUND

Patients with diabetes mellitus (DM) have a higher risk of sudden cardiac death. Factors associated with the risk profiles of coronary artery disease (CAD) patients with DM are not well established. Heart rate turbulence (HRT) and T-wave alternans (TWA) are often used to predict arrhythmia events.

METHODS AND RESULTS

HRT and TWA were measured in two independent groups: the ARTEMIS cohort study and the REFINE-ICD randomized trial. ARTEMIS assesses risk 3-12 months after coronary angiography in patients with CAD. The initial 1001 patients in ARTEMIS, 526 with and 475 without DM, are included in this analysis. REFINE-ICD compares usual care versus usual care plus ICD therapy in patients with left ventricular (LV) ejection fraction (EF) values of 36-50% assessed 2-15 months after myocardial infarction. The initial 275 patients screened in REFINE ICD are included in this analysis. Abnormal HRT plus TWA was more common in patients with versus without DM in ARTEMIS (125/526, 24% vs 63/475, 13%; P < 0.001) and REFINE-ICD (43/55, 78% vs 55/220, 25%; P < 0.001), respectively. Abnormal HRT plus TWA was also more common in patients with LVEF values < 50% (28%) vs ≥ 50% (18%; P < 0.001) in ARTEMIS and LVEF values below the population median of 42% (60/138, 43%) versus above the median (38/137, 28%; P < 0.01) in REFINE-ICD.

CONCLUSIONS

Abnormal HRT plus TWA is more common in CAD patients with DM compared with the patients without DM and is related to the severity of LV dysfunction.

CLINICAL TRIAL REGISTRATION INFORMATION

http://www.clinicaltrials.gov, NCT01426685; http://www.clinicaltrials.gov, NCT00673842.

[Heart failure. Cardiovascular autonomic neuropathy in patients with diabetes mellitus]

In spite of new therapy options the life expectancy of patients with diabetes mellitus is clearly reduced compared to the average population. In addition to coronary heart disease and diabetic cardiomyopathy, cardiac autonomic neuropathy (CAN) is also a factor in patients with diabetes mellitus. The CAN is an impairment of cardiovascular control. A reduced variability of heart rate up to the point of a fixed heart rate are symptoms of CAN. In addition symptomatic hypotension, a reduced left ventricular ejection fraction, cardiac arrhythmia and sudden cardiac death are also signs of CAN. Prevalence rates of CAN increase with age and are approximately 38 % in patients 40-70 years old with diabetes mellitus type 1 and 44 % in patients with diabetes mellitus type 2. The disease is usually documented using miscellaneous cardiovascular autonomic tests so that therapy can be started as soon as possible.

Heart rate complexity in sinoaortic-denervated mice

NEW FINDINGS

What is the central question of this study? New measurements for cardiovascular complexity, such as detrended fluctuation analysis (DFA) and multiscale entropy (MSE), have been shown to predict cardiovascular outcomes. Given that cardiovascular diseases are accompanied by autonomic imbalance and decreased baroreflex sensitivity, the central question is: do baroreceptors contribute to cardiovascular complexity? What is the main finding and its importance? Sinoaortic denervation altered both DFA scaling exponents and MSE, indicating that both short- and long-term mechanisms of complexity are altered in sinoaortic denervated mice, resulting in a loss of physiological complexity. These results suggest that the baroreflex is a key element in the complex structures involved in heart rate variability regulation. Recently, heart rate (HR) oscillations have been recognized as complex behaviours derived from non-linear processes. Physiological complexity theory is based on the idea that healthy systems present high complexity, i.e. non-linear, fractal variability at multiple scales, with long-range correlations. The loss of complexity in heart rate variability (HRV) has been shown to predict adverse cardiovascular outcomes. Based on the idea that most cardiovascular diseases are accompanied by autonomic imbalance and a decrease in baroreflex sensitivity, we hypothesize that the baroreflex plays an important role in complex cardiovascular behaviour. Mice that had been subjected to sinoaortic denervation (SAD) were implanted with catheters in the femoral artery and jugular vein 5 days prior to the experiment. After recording the baseline arterial pressure (AP), pulse interval time series were generated from the intervals between consecutive values of diastolic pressure. The complexity of the HRV was determined using detrended fluctuation analysis and multiscale entropy. The detrended fluctuation analysis α1 scaling exponent (a short-term index) was remarkably decreased in the SAD mice (0.79 ± 0.06 versus 1.13 ± 0.04 for the control mice), whereas SAD slightly increased the α2 scaling exponent (a long-term index; 1.12 ± 0.03 versus 1.04 ± 0.02 for control mice). In the SAD mice, the total multiscale entropy was decreased (13.2 ± 1.3) compared with the control mice (18.9 ± 1.4). In conclusion, fractal and regularity structures of HRV are altered in SAD mice, affecting both short- and long-term mechanisms of complexity, suggesting that the baroreceptors play a considerable role in the complex structure of HRV.