Cardiac autonomic neuropathy in patients with diabetes mellitus: current perspectives

Effects of adipose tissues on the relationship between type 2 diabetes mellitus and reduced heart rate variability: mediation analysis

BACKGROUND

Type 2 diabetes mellitus (T2DM) is associated with decreased heart rate variability (HRV) with an unclear intermediate mechanism. This study aimed to conduct mediation analysis to explore the impact of various adipose tissues on the relationship between T2DM and HRV.

METHODS

A total of 380 participants were enrolled for analysis, including 249 patients with T2DM and 131 non-diabetic controls. The thicknesses of four adipose tissues (subcutaneous, extraperitoneal, intraperitoneal, and epicardial) were measured by abdominal ultrasound or echocardiography respectively. HRV was assessed by 24-hour Holter for monitoring both frequency domain indices (LF, HF, and LF/HF) and time domain indices (SDNN, SDANN, SDNN index, rMSSD and pNN50). Mediation analysis was used toexamine whether adipose tissues mediated the relationship between T2DM and each index of HRV. Then, a latent variable - HRV burden - was constructed by structural equation model with selected HRV indices to comprehensively assess the whole HRV.

RESULTS

Compared to non-diabetic controls, patients with T2DM exhibited a significant reduction in indices of HRV, and a remarkable increase in the thicknesses of extraperitoneal, intraperitoneal, and epicardial adipose tissues. Mediation analysis found significant indirect effects of T2DM on six indices of HRV, including HF, SDNN, SDANN, SDNN index, rMSSD, and pNN50, which was mediated by epicardial adipose tissue rather than other adipose tissues, with the mediation proportions of 64.21%, 16.38%, 68.33%, 24.34%, 24.10% and 30.51%, respectively. Additionally, epicardial adipose tissue partially mediated the relationship between T2DM and reduced HRV burden (24.26%), which composed by SDNN, SDNN index, rMSSD, and pNN50.

CONCLUSION

Epicardial adipose tissue partially mediated the relationship between T2DM and reduced HRV, which reinforces the value of targeting heart-specific visceral fat to prevent cardiac autonomic neuropathy in diabetes.

Cardiac autonomic neuropathy modified the association between obesity and hypoglycemia in type 2 diabetes

BACKGROUND

Previous studies have shown that increasing body mass index (BMI) was associated with decreased hypoglycemia in type 2 diabetes, but it remains uncertain whether this finding could be applied to patients with and without cardiac autonomic neuropathy (CAN).

METHODS

The study included 7789 participants with type 2 diabetes from action to control cardiovascular risk in diabetes (ACCORD) trail. CAN was defined as SDNN < 8.2 ms and RMSSD < 8.0 ms. Obesity was defined as BMI ≥ 30 kg/m2. Outcomes were identified as severe hypoglycemia requiring any assistance (HAA) or requiring medical assistance (HMA). We assessed the association between obesity and severe hypoglycemia in type 2 diabetes with or without CAN using COX regression models adjusted for baseline characteristics.

RESULTS

Over a median follow-up of 4.7 years, a total of 893 participants developed HAA and 584 participants developed HMA. Compared with non-obesity, obesity was associated with lower risk of severe hypoglycemia (HAA: hazard ratio [HR] 0.51, 95% confidence interval [CI] 0.38-0.68, P < 0.001; HMA: HR 0.57, 95% CI 0.40-0.82, P = 0.002) in CAN present group, but not in CAN absent group (HAA: HR 0.98, 95% CI 0.83-1.16, P = 0.830; HMA: HR 0.97, 95% CI 0.79-1.19, P = 0.754). Similarly, increasing BMI was associated with reduced severe hypoglycemic events in participants with CAN, but not in participants without CAN.

CONCLUSIONS

CAN modifies the association between obesity and hypoglycemia in type 2 diabetes. Type 2 diabetic individuals with CAN who are under weight control should pay attention to hypoglycemic events.

TRIAL REGISTRY

http://www.

CLINICALTRIALS

gov . Unique identifier: NCT00000620.

Compromised cardiac autonomic function in non-diabetic subjects with 1 h post-load hyperglycemia: a cross-sectional study

BACKGROUND

A compromised cardiac autonomic function has been found in subjects with insulin resistance related disorders such as obesity, impaired glucose tolerance (IGT) and type 2 diabetes and confers an increased risk of adverse cardiovascular outcomes. Growing evidence indicate that 1 h plasma glucose levels (1hPG) during an oral glucose tolerance test (OGTT) ≥ 155 mg/dl identify amongst subjects with normal glucose tolerance (NGT) a new category of prediabetes (NGT 1 h-high), harboring an increased risk of cardiovascular organ damage. In this study we explored the relationship between 1 h post-load hyperglycemia and cardiac autonomic dysfunction.

METHODS

Presence of cardiac autonomic neuropathy (CAN) defined by cardiovascular autonomic reflex tests (CARTs) and heart rate variability (HRV), assessed by 24-h electrocardiography were evaluated in 88 non-diabetic subjects subdivided on the basis of OGTT data in: NGT with 1 h PG < 155 mg/dl (NGT 1 h-low), NGT 1 h-high and IGT.

RESULTS

As compared to subjects with NGT 1 h-low, those with NGT 1 h-high and IGT were more likely to have CARTs defined CAN and reduced values of the 24 h time domain HVR parameters including standard deviation of all normal heart cycles (SDNN), standard deviation of the average RR interval for each 5 min segment (SDANN), square root of the differences between adjacent RR intervals (RMSSD), percentage of beats with a consecutive RR interval difference > 50 ms (PNN50) and Triangular index. Univariate analyses showed that 1hPG, but not fasting and 2hPG, was inversely associated with all the explored HVR parameters and positively with CARTs determined presence of CAN. In multivariate regression analysis models including several confounders we found that 1hPG was an independent contributor of HRV and presence of CAN.

CONCLUSION

Subjects with 1hPG ≥ 155 mg/dl have an impaired cardiac autonomic function.

Cardiovascular autonomic neuropathy in diabetes: an update with a focus on management

Cardiovascular autonomic neuropathy (CAN) is an under-recognised yet highly prevalent microvascular complication of diabetes. CAN affects approximately 20% of people with diabetes, with recent studies highlighting the presence of CAN in prediabetes (impaired glucose tolerance and/or impaired fasting glucose), indicating early involvement of the autonomic nervous system. Understanding of the pathophysiology of CAN continues to evolve, with emerging evidence supporting a potential link between lipid metabolites, mitochondrial dysfunction and genetics. Recent advancements, such as streamlining CAN detection through wearable devices and monitoring of heart rate variability, present simplified and cost-effective approaches for early CAN detection. Further research on the optimal use of the extensive data provided by such devices is required. Despite the lack of specific pharmacological interventions targeting the underlying pathophysiology of autonomic neuropathy, several studies have suggested a favourable impact of newer glucose-lowering agents, such as sodium-glucose cotransporter 2 inhibitors and glucagon-like peptide-1 receptor agonists, where there is a wealth of clinical trial data on the prevention of cardiovascular events. This review delves into recent developments in the area of CAN, with emphasis on practical guidance to recognise and manage this underdiagnosed condition, which significantly increases the risk of cardiovascular events and mortality in diabetes.

Analysis of gastric electrical rhythm in patients with type 2 diabetes mellitus

AIM

To analysis the change of electrogastrogram (EGG) in patients with type 2 diabetes mellitus (T2DM), and evaluate the prevalence of abnormal gastric electrical rhythm (AGER) and its relative influencing factors.

METHODS

A total of 65 patients with T2DM hospitalized at the Second Affiliated Hospital of Soochow University from Dec. 2020 to Dec. 2021 were included in the cross-sectional study. General information, clinical data, and medical history data of all study subjects, including name, gender, body mass index (BMI), duration of diabetes, anti-diabetic therapies, high blood pressure (HBP) history, smoking history, and medication history, were completely collected. The results of laboratory tests, including biochemical parameters, glycosylated hemoglobin (HbA1c), fasting C-peptide, 2 h postprandial C-peptide, 24 h urine total protein (24 hUTP), urine microalbumin creatinine ratio (UACR) and estimated glomerular filtration rate (eGFR) were recorded. EGG, Gastroparesis Cardinal Symptom Index (GCSI), gastric emptying ultrasound, fundus examination, carotid artery ultrasonography, cardiac autonomic function test, heart rate variability (HRV) were all examined and recorded as well. According to the results of EGG, the subjects were divided into normal gastric electrical rhythm (NGER) group and abnormal gastric electrical rhythm (AGER) group.

RESULTS

(1) Fasting blood glucose (FBG), HbA1c, the presence of diabetic peripheral neuropathy (DPN) and diabetic cardiac autonomic neuropathy (DCAN) were significantly higher in the AGER group (p < 0.05). Low frequency (LF) and high frequency (HF), the indicators of HRV, were significantly lower in the AGER group (p < 0.05). In addition, the prevalence of feeling excessively full after meals, loss of appetite, and stomach or belly visibly larger after meals of gastrointestinal symptoms of gastroparesis were significantly higher in the AGER group (p < 0.05). Multiple logistic regression analysis showed that FBG and the prevalence of DCAN were the independent risk factors.

CONCLUSION

AGER was associated with high FBG and the presence of DCAN. EGG examination is recommended for patients with gastrointestinal symptoms and clues of DCAN.

The impact of obstructive sleep apnea treatment on microvascular complications in patients with type 2 diabetes: a feasibility randomized controlled trial

STUDY OBJECTIVES

Obstructive sleep apnea (OSA) is associated with an increased risk of diabetes-related complications. Hence, it is plausible that continuous positive airway pressure (CPAP) could have a favorable impact on these complications. We assessed the feasibility of conducting a randomized control trial in patients with type 2 diabetes and OSA over 2 years.

METHODS

We conducted an open-label multicenter feasibility randomized control trial of CPAP vs no CPAP in patients with type 2 diabetes and OSA. Patients with resting oxygen saturation < 90%, central apnea index > 15 events/h, or Epworth Sleepiness Scale ≥ 11 were excluded. OSA was diagnosed using a multichannel portable device (ApneaLink Air, ResMed). The primary outcome measures were related to feasibility and the secondary outcomes were changes in various clinical and biochemical parameters related to diabetes outcomes.

RESULTS

Eighty-three (40 CPAP vs 43 no CPAP) patients were randomly assigned, with a median (interquartile range) follow-up of 645 (545, 861) days. CPAP compliance was inadequate, with a median usage of approximately 3.5 hours/night. Early CPAP use predicted longer-term compliance. The adjusted analysis showed a possible favorable association between being randomly assigned to CPAP and several diabetes-related end points (chronic kidney disease, neuropathy, and quality of life).

CONCLUSIONS

It was feasible to recruit, randomly assign, and achieve a high follow-up rate over 2 years in patients with OSA and type 2 diabetes. CPAP compliance might improve by a run-in period before randomization. A full randomized control trial is necessary to assess the observed favorable association between CPAP and chronic kidney disease , neuropathy, and quality of life in patients with type 2 diabetes.

CLINICAL TRIAL REGISTRATION

Registry: ISRCTN; Name: The impact of sleep disorders in patients with type 2 diabetes; URL: https://www.isrctn.com/ISRCTN12361838; Identifier: ISRCTN12361838.

CITATION

Makhdom EA, Maher A, Ottridge R, et al. The impact of obstructive sleep apnea treatment on microvascular complications in patients with type 2 diabetes: a feasibility randomized controlled trial. J Clin Sleep Med. 2024;20(6):947-957.

Prevalence and prognostic significance of cardiac autonomic neuropathy in community-based people with type 2 diabetes: the Fremantle Diabetes Study Phase II

BACKGROUND

There is a paucity of contemporary data on the prevalence and prognostic significance of cardiac autonomic neuropathy (CAN) from community-based cohorts with type 2 diabetes assessed using gold standard methods. The aim of this study was to assess these aspects of CAN in the longitudinal observational Fremantle Diabetes Study Phase II (FDS2).

METHODS

FDS2 participants were screened at baseline using standardised cardiovascular reflex tests (CARTs) of heart rate variation during deep breathing, Valsalva manoeuvre and standing. CAN (no/possible/definite) was assessed from the number of abnormal CARTs. Multinomial regression identified independent associates of CAN status. Cox proportional hazards modelling determined independent baseline predictors of incident heart failure (HF) and ischaemic heart disease (IHD), and all-cause mortality.

RESULTS

Of 1254 participants assessed for CAN, 86 (6.9%) were outside CART age reference ranges and valid CART data were unavailable for 338 (27.0%). Of the remaining 830 (mean age 62.3 years, 55.3% males, median diabetes duration 7.3 years), 51.0%, 33.7% and 15.3% had no, possible or definite CAN, respectively. Independent associates of definite CAN (longer diabetes duration, higher body mass index and resting pulse rate, antidepressant and antihypertensive therapies, albuminuria, distal sensory polyneuropathy, prior HF) were consistent with those reported previously. In Kaplan-Meier analysis, definite CAN was associated with a lower likelihood of incident IHD and HF versus no/possible CAN (P < 0.001) and there was a graded increase in all-cause mortality risk from no CAN to possible and definite CAN (P < 0.001). When CAN category was added to the most parsimonious models, it was not a significant independent predictor of IHD (P ≥ 0.851) or HF (P ≥ 0.342). Possible CAN (hazard ratio (95% CI) 1.47 (1.01, 2.14), P = 0.046) and definite CAN (2.42 (1.60, 3.67), P < 0.001) increased the risk of all-cause mortality versus no CAN.

CONCLUSIONS

Routine screening for CAN in type 2 diabetes has limited clinical but some prognostic value.

Associations of age-adjusted coefficient of variation of R-R intervals with autonomic and peripheral nerve function in non-elderly persons with diabetes

AIMS/INTRODUCTION

Early diagnosis of diabetes-associated cardiac autonomic neuropathy using the coefficient of variation of R-R intervals (CVRR) may improve outcomes for individuals with diabetes. The present study examined the associations of decreased CVRR at rest and during deep breathing (DB) with other autonomic nerve function parameters.

MATERIALS AND METHODS

The electronic records of 141 inpatients with diabetes (22-65 years) admitted to our hospital between March 2015 and March 2019 were analyzed retrospectively. After assessment by exclusion criteria, 51 inpatients were included. All inpatients were assessed for peripheral and autonomic nerve function, clinical characteristics, and physical abilities.

RESULTS

Inpatients with decreased CVRR at rest (n = 9 (17.6%)) and during DB (n = 12 (23.5%)) had a longer duration of known diabetes, a higher prevalence of diabetic retinopathy, lower body mass index (BMI), skeletal mass index (SMI), and knee extension strength, and a higher proportion of impaired standing balance. Decreased CVRR at rest was associated with a greater fall in diastolic BP from supine to standing, higher resting HR, longer QTc, longer time of voiding, and sensory symptoms.

CONCLUSIONS

Decreased CVRR at rest and during deep breathing was associated with lower BMI, SMI, and knee strength and a higher proportion of impaired standing balance among non-elderly inpatients with diabetes. Decreased CVRR at rest appeared more strongly associated with a greater orthostatic BP decline, higher resting heart rate, longer QTc, lower urinary tract dysfunction, and sensory symptoms than a decreased CVRR during deep breathing.

Diabetes foot complications and standardized mortality rate in type 2 diabetes

AIM

To quantify the impact of foot complications on mortality outcomes in people with type 2 diabetes (T2D), and how routinely measured factors might modulate that risk.

MATERIALS AND METHODS

Data for individuals with T2D for 2010-2020, from the Salford Integrated Care Record (Salford, UK), were extracted for laboratory and clinical data, and deaths. Annual expected deaths were taken from Office of National Statistics mortality data. An index of multiple deprivation (IMD) adjusted the standardized mortality ratio (SMR_IMD). Life years lost per death (LYLD) was estimated from the difference between expected and actual deaths.

RESULTS

A total of 11 806 T2D patients were included, with 5583 new diagnoses and 3921 deaths during 2010-2020. The number of expected deaths was 2135; after IMD adjustment, there were 2595 expected deaths. Therefore, excess deaths numbered 1326 (SMR_IMD 1.51). No foot complications were evident in n = 9857. This group had an SMR_IMD of 1.13 and 2.74 LYLD. In total, 2979 patients had any foot complication recorded. In this group, the SMD_IMR was 2.29; of these, 2555 (75%) had only one foot complication. Patients with a foot complication showed little difference in percentage HbA1c more than 58 mmol/mol. In multivariate analysis, for those with a foot complication and an albumin-to-creatinine ratio of more than 3 mg/mmol, the odds ratio (OR) for death was 1.93, and for an estimated glomerular filtration rate of less than 60 mL/min/1.73m2 , the OR for death was 1.92.

CONCLUSIONS

Patients with T2D but without a foot complication have an SMR_IMD that is only slightly higher than that of the general population. Those diagnosed with a foot complication have a mortality risk that is double that of those without T2D.

Dysfunction of peripheral somatic and autonomic nervous system in patients with severe forms of Crohn's disease on biological therapy with TNFα inhibitors-A single center study

OBJECTIVE

Crohn's disease (CD) can be associated with a wide range of extraintestinal manifestations (EIMs), including neurological ones. Published studies differ in their conclusions about the epidemiology and etiopathogenesis of neurological EIMs. The aims of this study were to demonstrate the presence and find risk factors of peripheral (somatic and autonomic) neuropathy patients with severe CD on anti-TNFα biological therapy.

MATERIAL AND METHODS

A clinical examination focusing on detection of peripheral sensor-motor nervous dysfunction (including Sudoscan) and examination of autonomic nervous system dysfunction (using Ewing´s battery tests and spectral analysis) together with laboratory tests and collection of demographic data followed by administration of questionnaires were performed on a total of 30 neurologically asymptomatic outpatients with severe CD on anti-TNFα biological therapy.

RESULTS

Peripheral sensor-motor nervous function via clinical neurological examination was pathological in 36.7% and Sudoscan in 33.3% of cases. Statistically significant associations between vibration perception test and age, CD and biological therapy duration, body mass index and Crohn's Disease Activity Index were proved while statistically significant associations between temperature perception test and age and BMI were proved as well. Additionally, a decrease of total protein in a patient´s serum below the physiological cut-off in the 6 months prior to measurement was associated with a pathological result of a Sudoscan. Cardiovascular autonomic neuropathy based on Ewing´s battery tests was present in 56.7% of patients, no statistically significant risk factors were found. Our peripheral neuropathy questionnaire correlated with the results of the Sudoscan test and some tests of the clinical examination of peripheral sensor-motor nervous function (discriminatory contact perception test, temperature perception test).

CONCLUSIONS

This study demonstrated a relatively high prevalence of peripheral (especially autonomic) neuropathy and verified some risk factors for the development of peripheral somatic neuropathy in asymptomatic patients with severe form of CD on anti-TNFα biological therapy.

Cardiac Autonomic Neuropathy in Newly Diagnosed Patients With Type 2 Diabetes Mellitus

INTRODUCTION

Cardiac autonomic neuropathy (CAN) is a debilitating complication in diabetes mellitus, leading to life-threatening arrhythmias and various impairments. Its prevalence varies widely, and early detection and management are crucial. This study investigates the prevalence of CAN in newly diagnosed type 2 diabetes mellitus patients in Central India, comparing them to a control group.

METHODOLOGY

This case-control study included 35 newly diagnosed type 2 diabetes mellitus patients and 35 age-matched healthy controls from the general population. Cardiac autonomic function testing (AFT) was done by heart rate variability (HRV), the deep breathing test (DBT), the cold pressor test (CPT), and the lying-to-standing test (LST). Parameters were recorded and analyzed using statistical tests.

RESULTS

Patients with type 2 diabetes mellitus had significantly higher weight, BMI, fasting blood sugar, post-prandial blood sugar, urine albumin-creatinine ratios, and systolic and diastolic blood pressure than controls. Abnormalities in HRV and E: I ratio during the DBT and CPT were more prevalent in these patients. Parasympathetic dysfunction (delta HR) and a lower E: I ratio were also significantly high in this group. Also, LST results suggested a greater likelihood of orthostatic symptoms in the patients' group.

CONCLUSION

This study highlights the importance of AFT in diagnosing early CAN in newly diagnosed patients. Early diagnosis and management of diabetic CAN are essential to prevent complications.

A three-month physical training program improves cardiovascular autonomic function in patients with metabolic syndrome with and without diabetes - a pilot study

Introduction

Vascular complications and neuropathy may develop in the presence of metabolic syndrome. The aim of our study was to measure the cardiovascular autonomic function following physical training in patients with metabolic syndrome with and without diabetes.

Subjects and methods

56 patients with metabolic syndrome (32 men/24 women, 40 non-diabetic patients (NDMetS)/16 diabetic patients (DMetS) [mean ± SD]: age: 50.35 ± 8.03 vs. 56.8 ± 9.30 years, p=0.023; baseline BMI: 32.2 ± 7.03 vs. 32.8 ± 5.94 kg/m2, p=0.739) were involved in our study. All tests and measurements were carried out before and following a 3-month physical training period. Autonomic function was assessed by means of five standard cardiovascular reflex tests. ECG repolarization parameters, including short-term QT variability and stress-ECG were also measured.

Results

In the whole population, Valsalva-ratio (VR) and the autonomic score (AS) improved following training (VR: 1.49 ± 0.24 vs. 1.64 ± 0.34, p=0.001; AS: 2.05 ± 1.73 vs. 1.41 ± 1.36, p=0.015) accompanied by the significant decrease of the systolic (150.3 ± 16.12 vs. 134.1 ± 16.67 mmHg, p<0.001) and diastolic (90.64 ± 12.8 vs. 82.79 ± 11.1 mmHg, p<0.001) blood pressure. An improvement in VR was detected in NDMetS patients following training (1.51 ± 0.24 vs. 1.67 ± 0.31, p= 0.002). No significant changes could be detected in autonomic tests' results in the DMetS patient group following training. The applied exercise training program did not lead to significant changes in ECG repolarization. The stress-ECG test in the whole study population yielded a significant increase in the test duration (12.9 ± 3.76 vs. 15.1 ± 2.96 min, p<0.001) and in the test load (10.5 ± 2.78 vs. 11.6 ± 2.39 MET, p<0.001). The load capability improved significantly in both subgroups: 11.1 ± 2.04 vs. 12.1 ± 1.82, (p<0.001) and 9.0 ± 3.64 vs. 10.4 ± 3.05, (p=0.033) in subpopulations of NDMetS and DMetS, respectively. The DMetS patients achieved a significantly lower MET score at baseline (p=0.039) and following training (p=0.044) in comparison to the NDMetS patients.

Conclusion

The three-month exercise program improved the Valsalva-ratio and the AN score in the MetS patients, that is potentially protective against cardiovascular events. The training had some beneficial effect on blood pressure and the results of the stress-ECG tests in both groups. The absence of significant change in the reflex tests in DMetS group reflects an impaired adaptation compared to the NDMestS group.

Assessment of Triglyceride Glucose Index in Type 2 Diabetes Mellitus Patients With and Without Cardiac Autonomic Neuropathy

Background Cardiac autonomic neuropathy (CAN) is a major complication of type 2 diabetes mellitus (T2DM). Hyperglycaemia and hypertriglyceridemia are known risk factors in the development of CAN with T2DM. The triglyceride glucose (TyG) index is calculated using both the fasting blood glucose (FBG) and fasting triglyceride levels (FTG). There is a paucity of literature revealing a direct relationship between the TyG index and CAN in T2DM patients of the south Indian population. Objective To assess the TyG index levels in T2DM with and without CAN. Methods A cross-sectional study was performed, involving 100 T2DM patients (58 males and 42 females) aged between 30 and 60 years, who attended medicine OPD, Sri Venkateswaraa Medical College, Hospital and Research Centre (SVMCH & RC) during the study period. Age, duration of illness, height, weight, waist circumference (WC), hip circumference (HC), body mass index (BMI), systolic blood pressure (SBP) and diastolic blood pressure (DBP) were measured. Glycated hemoglobin (HbA1C) and lipid profile values were taken from patients' recent medical records. Ewing autonomic function tests were used to diagnose CAN, which included heart rate response to standing, heart rate response to deep breathing, heart rate response to Valsalva maneuver, blood pressure response to standing and blood pressure response to isometric handgrip. FBG and FTG were measured and the TyG index was calculated from these parameters. Statistical Product and Service Solutions (SPSS) (IBM SPSS Statistics for Windows, Version 20.0, Armonk, NY) was used for the statistical analysis and a 'P' value < 0.05 was considered statistically significant. Results In our study, out of 100 T2DM patients, 42 patients were diagnosed with CAN. The mean levels of TyG Index, HbA1C, FBG, FTG, BMI and WC were significantly (p<0.05) higher in T2DM patients with CAN when compared to T2DM without CAN. We couldn't find any significant difference (p<0.05) in age, duration of illness, blood pressure and lipid profile parameters between the groups. Conclusion We found that abdominal obesity, hyperglycemia, and hypertriglyceridemia are the risk factors for developing CAN in T2DM patients. Our study results also showed that the TyG index can be used to predict CAN in T2DM patients.

Impact of Intensive Glycemic Treatment on Diabetes Complications-A Systematic Review

Diabetes complications can be related to the long duration of the disease or chronic hyperglycemia. The follow-up of diabetic patients is based on the control of chronic hyperglycemia, although this correction, if obtained rapidly in people living with severe chronic hyperglycemia, can paradoxically interfere with the disease or even induce complications. We reviewed the literature describing the impact of the rapid and intense treatment of hyperglycemia on diabetic complications. The literature review showed that worsening complications occurred significantly in diabetic microangiopathy with the onset of specific neuropathy induced by the correction of diabetes. The results for macroangiopathy were somewhat mixed with the intensive and rapid correction of chronic hyperglycemia having a neutral impact on stroke and myocardial infarction but a significant increase in cardiovascular mortality. The management of diabetes has now entered a new era with new therapeutic molecules, such as gliflozin for patients living with type 2 diabetes, or hybrid insulin delivery systems for patients with insulin-treated diabetes. Our manuscript provides evidence in support of these personalized and progressive algorithms for the control of chronic hyperglycemia.

Reactive Hyperemia and Cardiovascular Autonomic Neuropathy in Type 2 Diabetic Patients: A Systematic Review of Randomized and Nonrandomized Clinical Trials

Objective: This work aimed to determine the relationship between the autonomic nervous system and reactive hyperemia (RH) in type 2 diabetes patients with and without cardiovascular autonomic neuropathy (CAN). Methodology: A systematic review of randomized and nonrandomized clinical studies characterizing reactive hyperemia and autonomic activity in type 2 diabetes patients with and without CAN was performed. Results: Five articles showed differences in RH between healthy subjects and diabetic patients with and/or without neuropathy, while one study did not show such differences between healthy subjects and diabetic patients, but patients with diabetic ulcers had lower RH index values compared to healthy controls. Another study found no significant difference in blood flow after a muscle strain that induced reactive hyperemia between normal subjects and non-smoking diabetic patients. Four studies measured reactive hyperemia using peripheral arterial tonometry (PAT); only two found a significantly lower endothelial-function-derived measure of PAT in diabetic patients than in those without CAN. Four studies measured reactive hyperemia using flow-mediated dilation (FMD), but no significant differences were reported between diabetic patients with and without CAN. Two studies measured RH using laser Doppler techniques; one of them found significant differences in the blood flow of calf skin after stretching between diabetic non-smokers and smokers. The diabetic smokers had neurogenic activity at baseline that was significantly lower than that of the normal subjects. The greatest evidence revealed that the differences in RH between diabetic patients with and without CAN may depend on both the method used to measure hyperemia and that applied for the ANS examination as well as the type of autonomic deficit present in the patients. Conclusions: In diabetic patients, there is a deterioration in the vasodilator response to the reactive hyperemia maneuver compared to healthy subjects, which depends in part on endothelial and autonomic dysfunction. Blood flow alterations in diabetic patients during RH are mainly mediated by sympathetic dysfunction. The greatest evidence suggests a relationship between ANS and RH; however, there are no significant differences in RH between diabetic patients with and without CAN, as measured using FMD. When the flow of the microvascular territory is measured, the differences between diabetics with and without CAN become evident. Therefore, RH measured using PAT may reflect diabetic neuropathic changes with greater sensitivity compared to FMD.

Role of purinergic receptors in cardiac sympathetic nerve injury in diabetes mellitus

Diabetic cardiac autonomic neuropathy is a common and serious chronic complication of diabetes, which can lead to sympathetic and parasympathetic nerve imbalance and a relative excitation of the sympathetic nerve. Purinergic receptors play a crucial role in this process. Diabetic cardiac sympathetic nerve injury affects the expression of purinergic receptors, and activated purinergic receptors affect the phosphorylation of different signaling pathways and the regulation of inflammatory processes. This paper introduces the abnormal changes of sympathetic nerve in diabetes mellitus and summarizes the recently published studies on the role of several purinergic receptor subtypes in diabetic cardiac sympathetic nerve injury. These studies suggest that purinergic receptors as novel drug targets are of great significance for the treatment of diabetic autonomic neuropathy. This article is part of the Special Issue on "Purinergic Signaling: 50 years".

Effect of Ramipril on Cardiac Autonomic Neuropathy in Patients With Type II Diabetes Mellitus

Background Cardiovascular autonomic neuropathy (CAN), an important form of DAN is caused by the impairment of the autonomic nerve fibers that innervate the heart and blood vessels and leads to abnormalities in cardiovascular dynamics. The earliest finding of CAN, even at the subclinical stage, is a decrease in heart rate variability (HRV). Objective The objective is to assess the effect of ramipril 2.5mg once daily on cardiac autonomic neuropathy in type II DM patients as an add-on to a standard antidiabetic regimen for a duration of 12 months. Materials and methods A prospective, open-label, randomized, parallel-group study was conducted on type II DM with autonomic dysfunction. Patients in Group A received tablet ramipril 2.5mg daily along with the standard antidiabetic regimen which consist of Tab Metformin 500mg twice a day and Tab Vildagliptin 50mg twice a day and group B received only the standard antidiabetic regimen for 12 months. Results Among 26 patients with CAN, 18 patients completed the study. After one year in group A, Delta HR value increases from 9.77±1.71 to 21.44±8.44 and the E:I ratio (ratio of the longest R-R interval during expiration and shortest R-R interval during inspiration) improved from 1.23±0.35 to 1.29±0.23 signifying significant improvement in parasympathetic tone. Results of the postural test showed significant improvement in SBP. Analysis of HRV by time domain method showed that the standard deviation of RR (SDRR) interval and Standard deviation of differences between adjacent RR interval (SDSD) value increased significantly in group A. Analysis of HRV frequency domain indices showed that LFP:HFP ratio improved after treatment in ramipril group indicating improvement in sympatho-vagal balance. Conclusion Ramipril improves parasympathetic component more as compared to sympathetic component of DCAN in type II DM. Ramipril could be a promising option having favorable long-term outcomes in diabetic patients especially when treatment begins at subclinical stage.

Diabetes Mellitus and Heart Failure: Epidemiology, Pathophysiologic Mechanisms, and the Role of SGLT2 Inhibitors

Diabetes mellitus (DM) and heart failure (HF) are frequently encountered afflictions that are linked by a common pathophysiologic background. According to landmark studies, those conditions frequently coexist, and this interaction represents a poor prognostic indicator. Based on mechanistic studies, HF can be propagated by multiple pathophysiologic pathways, such as inflammation, oxidative stress, endothelial dysfunction, fibrosis, cardiac autonomic neuropathy, and alterations in substrate utilization. In this regard, DM may augment myocardial inflammation, fibrosis, autonomic dysfunction, and lipotoxicity. As the interaction between DM and HF appears critical, the new cornerstone in DM and HF treatment, sodium-glucose cotransporter-2 inhibitors (SGLT2i), may be able to revert the pathophysiology of those conditions and lead to beneficial HF outcomes. In this review, we aim to highlight the deleterious pathophysiologic interaction between DM and HF, as well as demonstrate the beneficial role of SGLT2i in this field.

Diabetes-Induced Cardiac Autonomic Neuropathy: Impact on Heart Function and Prognosis

Cardiovascular autonomic neuropathy (CAN) is a severe complication of the advance stage of diabetes. More than 50% of diabetic patients diagnosed with peripheral neuropathy will have CAN, with clinical manifestations including tachycardia, severe orthostatic hypotension, syncope, and physical exercise intolerance. Since the prevalence of diabetes is increasing, a concomitant increase in CAN is expected and will reduce quality of life and increase mortality. Autonomic dysfunction is associated with reduced baroreflex sensitivity and impairment of sympathetic and parasympathetic modulation. Various autonomic function tests are used to diagnose CAN, a condition without adequate treatment. It is important to consider the control of glucose level and blood pressure as key factors for preventing CAN progression. However, altered biomarkers of inflammatory and endothelial function, increased purinergic receptor expression, and exacerbated oxidative stress lead to possible targets for the treatment of CAN. The present review describes the molecular alterations seen in CAN, diagnosis, and possible alternative treatments.

Heart rate-corrected QT interval prolongation is associated with decreased heart rate variability in patients with type 2 diabetes

We investigated the association between the heart rate-corrected QT interval (QTc interval) measured by standard electrocardiography and heart rate variability (HRV) in patients with type 2 diabetes mellitus (T2DM). From March 1, 2009, to December 12, 2009, 411 patients with T2DM who underwent resting 12-lead electrocardiography and cardiovascular autonomic function testing concurrently without the exclusion criteria were consecutively recruited in this cross-sectional study. Time- and frequency-domain HRV variables were assessed for 5 minutes by beat-to-beat HRV recording. The QT interval was corrected for the heart rate using Bazett's formula. QTc interval measurements of >440 ms were considered abnormally prolonged. The mean age and diabetes duration were 56.3 ± 10.6 years and 9.6 ± 7.3 years, respectively. A total of 90 patients had QTc interval prolongation (21.9%). The participants with a prolonged QTc interval were older (59.4 ± 10.1 years vs 55.5 ± 10.6 years, P = .002), were more likely to be a woman (72.2% vs 51.7%, P = .001), had a higher prevalence of hypertension (46.7% vs 33.4%, P = .022), had a higher hemoglobin A1c level (8.8% ± 2.2% vs 8.2% ± 1.8%, P = .045), and had decreased values for the variables measuring HRV, except for the low frequency (LF)/high frequency (HF) ratio (total power [TP], 147.7 [74.1-335.9] ms vs 328.7 [185.7-721.7] ms, P = .002). After adjusting for multiple confounders, QTc interval prolongation was associated with the lowest quartile of the HRV parameters of TP (odds ratio [OR] = 3.99; 95% confidence interval [CI]: 2.29-6.96), HF (OR = 3.20; 95% CI: 1.84-5.58), LF (OR = 3.68; 95% CI: 2.10-6.43), standard deviation of the normal-to-normal interval (OR = 3.31; 95% CI: 1.89-5.77), and root-mean-square of the successive differences (OR = 1.98; 95% CI: 1.13-3.47) in patients with T2DM. Decreased values for the variables measuring HRV, except for the LF/HF ratio, might be associated with QTc interval prolongation in patients with T2DM.

Synergistic effect of chronic kidney disease, neuropathy, and retinopathy on all-cause mortality in type 1 and type 2 diabetes: a 21-year longitudinal study

Background

The prognostic value of common and frequently associated diabetic microvascular complications (MVC), namely chronic kidney disease (CKD), cardiac autonomic neuropathy (CAN), peripheral neuropathy (DPN), and retinopathy (DR), is well established. However, the impact of their different combinations on long-term mortality has not been adequately assessed.

Methods

We retrospectively analyzed 21-year longitudinal data from 303 patients with long-standing type 1 (T1D) or type 2 diabetes (T2D), who were thoroughly characterized at baseline for the presence of MVC using 99mTc-DTPA dynamic renal scintigraphy, overnight urine collection, cardiovascular autonomic tests, monofilament testing, and dilated fundus oculi examination.

Results

After a 5,244 person-years follow-up, a total of 133 (43.9%) deaths occurred. The presence of CKD and CAN, regardless of other MVC, increased the adjusted all-cause mortality risk by 117% (HR 2.17 [1.45–3.26]) and 54% (HR 1.54 [1.01–2.36]), respectively. Concomitant CKD&CAN at baseline were associated with the highest mortality risk (HR 5.08 [2.52–10.26]), followed by CKD&DR (HR 2.95 [1.63–5.32]), and CAN&DR (HR 2.07 [1.11–3.85]). Compared with patients free from MVC, the mortality risk was only numerically higher in those with any isolated MVC (HR 1.52 [0.87–2.67]), while increased by 203% (HR 3.03 [1.62–5.68]) and 692% (HR 7.92 [2.93–21.37]) in patients with two and three concomitant MVC, respectively.

Conclusions

Our study demonstrates the long-term, synergistic, negative effects of single and concomitant diabetic MVC on all-cause mortality, which should encourage comprehensive screenings for MCV in both T1D and T2D to improve risk stratification and treatment.

Skin Microhemodynamics and Mechanisms of Its Regulation in Type 2 Diabetes Mellitus

The review presents modern ideas about peripheral microhemodynamics, approaches to the ana-lysis of skin blood flow oscillations and their diagnostic significance. Disorders of skin microhemodynamics in type 2 diabetes mellitus (DM) and the possibility of their interpretation from the standpoint of external and internal interactions between systems of skin blood flow regulation, based on a comparison of couplings in normal and pathological conditions, including models of pathologies on animals, are considered. The factors and mechanisms of vasomotor regulation, among them receptors and signaling events in endothelial and smooth muscle cells considered as models of microvessels are discussed. Attention was drawn to the disturbance of Ca2+-dependent regulation of coupling between vascular cells and NO-dependent regulation of vasodilation in diabetes mellitus. The main mechanisms of insulin resistance in type 2 DM are considered to be a defect in the number of insulin receptors and impaired signal transduction from the receptor to phosphatidylinositol-3-kinase and downstream targets. Reactive oxygen species plays an important role in vascular dysfunction in hyperglycemia. It is assumed that the considered molecular and cellular mechanisms of microhemodynamics regulation are involved in the formation of skin blood flow oscillations. Parameters of skin blood microcirculation can be used as diagnostic and prognostic markers for assessing the state of the body.

Risk of incident obstructive sleep apnoea in patients with type 1 diabetes: a population-based retrospective cohort study

AIMS/HYPOTHESIS

People with type 2 diabetes are at increased risk of developing obstructive sleep apnoea. However, it is not known whether people with type 1 diabetes are also at an increased risk of obstructive sleep apnoea. This study aimed to examine whether people with type 1 diabetes are at increased risk of incident obstructive sleep apnoea compared with a matched cohort without type 1 diabetes.

METHODS

We used a UK primary care database, The Health Improvement Network (THIN), to perform a retrospective cohort study between January 1995 and January 2018 comparing sleep apnoea incidence between patients with type 1 diabetes (exposed) and without type 1 diabetes (unexposed) (matched for age, sex, BMI and general practice). The outcome was incidence of obstructive sleep apnoea. Baseline covariates and characteristics were assessed at the start of the study based on the most recent value recorded prior to the index date. The Cox proportional hazards regression model was used to estimate unadjusted and adjusted hazard ratios, based on a complete-case analysis.

RESULTS

In total, 34,147 exposed and 129,500 matched unexposed patients were included. The median follow-up time was 5.43 years ((IQR 2.19-10.11), and the mean BMI was 25.82 kg/m2 (SD 4.33). The adjusted HR for incident obstructive sleep apnoea in patients with type 1 diabetes vs those without type 1 diabetes was 1.53 (95% CI 1.25, 1.86; p<0.001). Predictors of incident obstructive sleep apnoea in patients with type 1 diabetes were older age, male sex, obesity, being prescribed antihypertensive or lipid-lowering drugs, atrial fibrillation and depression.

CONCLUSIONS/INTERPRETATION

Individuals with type 1 diabetes are at increased risk of obstructive sleep apnoea compared with people without diabetes. Clinicians should suspect obstructive sleep apnoea in patients with type 1 diabetes if they are old, have obesity, are male, have atrial fibrillation or depression, or if they are taking lipid-lowering or antihypertensive drugs.

Acute Changes in Heart Rate Variability to Glucose and Fructose Supplementation in Healthy Individuals: A Double-Blind Randomized Crossover Placebo-Controlled Trial

Simple Summary

In this study, we investigated the cardio-autonomic stress responses to the ingestion of liquid glucose, fructose, a combination thereof and a placebo in healthy individuals at rest. The cardio-autonomic response was more pronounced in all groups with carbohydrates compared to placebo indicating an increased cardio-autonomic stress response resulting in a reduced heart-rate variability. When investigating different levels of blood glucose, the findings showed a significant decline in heart-rate variability with increasing blood glucose levels. This was also seen with severely low levels of blood glucose. The speed of how quick blood glucose increased and decreased also impacted the cardio-autonomic response which further deteriorated heart-rate variability. These findings indicate that healthy human’s autonomic system responds quickly to changes in their blood glucose.

Abstract

Background: It is unknown how different types of carbohydrates alter the cardio-autonomic system in healthy individuals. Therefore, the aim of this study was to investigate how heart-rate variability changes to single dose ingestion of glucose, fructose, glucose and fructose, and an artificial sweetener (sucralose). Methods: In a double-blind randomized crossover placebo-controlled setting, 15 participants received all study-specific substances in liquid form. During each 2-h visit, venous blood glucose was measured in a 5-min interval while heart-rate variability was measured continuously via Holter-electrocardiograph. Results: Ingestion of different types of carbohydrates and sucralose showed significant differences for heart rate (p < 0.001), SDNN (p < 0.008), RMSSD (p < 0.001), pNN50 (p < 0.001) and blood pressure (p < 0.001). Different glucose levels significantly altered parameters of heart-rate variability and blood pressure (all p < 0.001), while the rate of change in blood glucose led to changes in heart rate variability, but not in heart rate (p = 0.25) or blood pressure (p = 0.99). Conclusions: Ingestion of different types of carbohydrates lead to reductions in heart-rate variability compared to a placebo. Blood glucose values above or below 70–90 mg/dL decreased heart rate variability while this was also seen for rapid glucose changes, yet not as pronounced. Healthy individuals should be conscious about carbohydrate intake while maintaining blood glucose levels between 70–90 mg/dL.

Vestibular-autonomic interactions: beyond orthostatic dizziness

PURPOSE OF REVIEW

This review aims to summarize the current literature describing vestibular-autonomic interactions and to describe their putative role in various disorders' clinical presentations, including orthostatic dizziness and motion sensitivity.

RECENT FINDINGS

The vestibular-autonomic reflexes have long been described as they relate to cardiovascular and respiratory function. Although orthostatic dizziness may be in part related to impaired vestibulo-sympathetic reflex (orthostatic hypotension), there are various conditions that may present similarly. A recent clinical classification aims to improve identification of individuals with hemodynamic orthostatic dizziness so that appropriate recommendations and management can be efficiently addressed. Researchers continue to improve understanding of the underlying vestibular-autonomic reflexes with recent studies noting the insular cortex as a cortical site for vestibular sensation and autonomic integration and modulation. Work has further expanded our understanding of the clinical presentation of abnormal vestibular-autonomic interactions that may occur in various conditions, such as aging, peripheral vestibular hypofunction, traumatic brain injury, and motion sensitivity.

SUMMARY

The vestibular-autonomic reflexes affect various sympathetic and parasympathetic functions. Understanding these relationships will provide improved identification of underlying etiology and drive improved patient management.

Exosomal microRNAs: potential targets for the prevention and treatment of diabetic cardiomyopathy

Diabetic cardiomyopathy (DCM), a condition in which myocardial dysfunction is caused by diabetes mellitus, has become an epidemic disorder in the world. DCM initially presents as diastolic relaxation dysfunction and will progress to heart failure in the absence of coronary artery disease, valvular disease, and other conventional cardiovascular risk factors such as hypertension and dyslipidemia. However, the underlying molecular mechanisms of DCM are poorly understood. Recent studies reveal that exosomal miRNAs are associated with multiple DCM risk factors and may act as potential therapeutic targets. Therefore, this review summarizes the recent advancements to understand the role of exosomal miRNAs in DCM development and explores potential preventative and therapeutic strategies.

The clinical profile and associated mortality in people with and without diabetes with Coronavirus disease 2019 on admission to acute hospital services

INTRODUCTION

To assess if in adults with COVID-19, whether those with diabetes and complications (DM+C) present with a more severe clinical profile and if that relates to increased mortality, compared to those with diabetes with no complications (DM-NC) and those without diabetes.

METHODS

Service-level data was used from 996 adults with laboratory confirmed COVID-19 who presented to the Queen Elizabeth Hospital Birmingham, UK, from March to June 2020. All individuals were categorized into DM+C, DM-NC, and non-diabetes groups. Physiological and laboratory measurements in the first 5 days after admission were collated and compared among groups. Cox proportional hazards regression models were used to evaluate associations between diabetes status and the risk of mortality.

RESULTS

Among the 996 individuals, 104 (10.4%) were DM+C, 295 (29.6%) DM-NC and 597 (59.9%) non-diabetes. There were 309 (31.0%) in-hospital deaths documented, 40 (4.0% of total cohort) were DM+C, 99 (9.9%) DM-NC and 170 (17.0%) non-diabetes. Individuals with DM+C were more likely to present with high anion gap/metabolic acidosis, features of renal impairment, and low albumin/lymphocyte count than those with DM-NC or those without diabetes. There was no significant difference in mortality rates among the groups: compared to individuals without diabetes, the adjusted HRs were 1.39 (95% CI 0.95-2.03, p = 0.093) and 1.18 (95% CI 0.90-1.54, p = 0.226) in DM+C and DM-C, respectively.

CONCLUSIONS

Those with COVID-19 and DM+C presented with a more severe clinical and biochemical profile, but this did not associate with increased mortality in this study.

Cardiac Sympathetic Positron Emission Tomography Imaging with Meta-[18F]Fluorobenzylguanidine is Sensitive to Uptake-1 in Rats

Dysfunction of the cardiac sympathetic nervous system contributes to the development of cardiovascular diseases including ischemia, heart failure, and arrhythmias. Molecular imaging probes such as meta-[¹²³I]iodobenzylguanidine have demonstrated the utility of assessing neuronal integrity by targeting norepinephrine transporter (NET, uptake-1). However, current radiotracers can report only on innervation due to suboptimal kinetics and lack sensitivity to NET in rodents, precluding mechanistic studies in these species. The objective of this work was to characterize myocardial sympathetic neuronal uptake mechanisms and kinetics of the positron emission tomography (PET) radiotracer meta-[¹⁸F]fluorobenzylguanidine ([¹⁸F]mFBG) in rats. Automated synthesis using spirocyclic iodonium(III) ylide radiofluorination produces [¹⁸F]mFBG in 24 ± 1% isolated radiochemical yield and 30-95 GBq/μmol molar activity. PET imaging in healthy rats delineated the left ventricle, with monoexponential washout kinetics (k_mono = 0.027 ± 0.0026 min^-1, A_mono = 3.08 ± 0.33 SUV). Ex vivo biodistribution studies revealed tracer retention in the myocardium, while pharmacological treatment with selective NET inhibitor desipramine, nonselective neuronal and extraneuronal uptake-2 inhibitor phenoxybenzamine, and neuronal ablation with neurotoxin 6-hydroxydopamine reduced myocardial retention by 33, 76, and 36%, respectively. Clearance of [¹⁸F]mFBG from the myocardium was unaffected by treatment with uptake-1 and uptake-2 inhibitors following peak myocardial activity. These results suggest that myocardial distribution of [¹⁸F]mFBG in rats is dependent on both NET and extraneuronal transporters and that limited reuptake to the myocardium occurs. [¹⁸F]mFBG may therefore prove useful for imaging intraneuronal dysfunction in small animals.

Leisure-Time Physical Activity and Glycemic Control Independently Predicts Cardiac Autonomic Neuropathy in Type 2 Diabetes Mellitus

BACKGROUND

Though cardiac autonomic neuropathy (CAN) is a common complication of type 2 diabetes mellitus (T2DM); still, there is lack of clarity on pathophysiological correlates for its onset and progression. Therefore, the purpose of this study was to investigate the predictive ability of lifestyle and cardiometabolic risk factors for CAN in T2DM patients.

METHODS

A total of 105 Indian T2DM patients were recruited in the present study. Cardiometabolic risk factors, such as glycemic control, lipids, resting heart rate, systolic and diastolic blood pressure, and lifestyle risk parameters, such as physical activity levels and sleep quality were assessed. Standard cardiovascular autonomic reflex tests were performed for diagnosing CAN by Ewing's criteria.

RESULTS

Leisure-time physical activity and glycosylated hemoglobin were significant independent predictors of CAN in T2DM. Leisure-time physical activity and glycosylated hemoglobin predicted the occurrence of CAN at cutoff values ≤4.68 metabolic equivalent-hours per week (P = .007) and >7.5% (P = .002), respectively.

CONCLUSIONS

The T2DM patients should be encouraged to engage in leisure-time physical activity of at least 4.68 metabolic equivalent-hours per week (equivalent to 1.2 h of walk or 0.6 h of jog per week) and therapeutic strategies for controlling hyperglycemia in T2DM should aim to reduce glycosylated hemoglobin below 7.5% to reduce CAN occurrence.

Insulin resistance is independently associated with cardiovascular autonomic neuropathy in type 2 diabetes

AIMS/INTRODUCTION

Diabetic cardiovascular autonomic neuropathy (DCAN) seriously threatens the prognosis and quality of life of patients with type 2 diabetes mellitus, associated with increased mortality. The present study aimed to investigate the relevant risk factors of DCAN.

MATERIALS AND METHODS

The present study enrolled a total of 109 patients with type 2 diabetes mellitus. DCAN was defined as a score of at least 2 points in Ewing tests. The updated homeostasis model assessment of insulin resistance (HOMA2-IR) based on fasting C-peptide was calculated to reflect insulin resistance. Logistic regression analysis, interaction and stratified analyses were used to investigate the relationship between HOMA2-IR or other indicators and DCAN. Receiver operating characteristic analysis was carried out to estimate the discriminative value of the variables independently associated with DCAN and to determine the optimal cut-off point of these models to screen DCAN.

RESULTS

The HOMA2-IR levels were significantly higher in patients with DCAN, and tended to be worsened with the progression of the DCAN. Logistic regression analysis showed an independent association between HOMA2-IR (odds ratio 39.30, 95% confidence interval 7.17-215.47) and DCAN. HOMA2-IR (area under the curve 0.878, 95% confidence interval 0.810-0.946; cut-off value 1.735) individually predicted DCAN significantly higher than the other independent risk factors individually used, whereas models combining HOMA2-IR and other risk factors did not significantly boost the diagnostic power.

CONCLUSIONS

Insulin resistance is independently associated with DCAN. HOMA2-IR presents to be a highly accurate and parsimonious indicator for DCAN screening. Patients with HOMA2-IR >1.735 are at a high risk of DCAN; thus, priority diagnostic tests should be carried out for these patients for timely integrated intervention.

Heart Rate Variability measured during rest and after orthostatic challenge to detect autonomic dysfunction in Type 2 Diabetes Mellitus using the Classification and Regression Tree model

BACKGROUND

According to the World Health Organization, one in ten adults will have Type 2 Diabetes Mellitus (T2DM) in the next few years. Autonomic dysfunction is one of the significant complications of T2DM. Autonomic dysfunction is usually assessed by standard Ewing's test and resting Heart Rate Variability (HRV) indices.

OBJECTIVE

Resting HRV has limited use in screening due to its large intra and inter-individual variations. Therefore, a combined approach of resting and orthostatic challenge HRV measurement with a machine learning technique was used in the present study.

METHODS

A total of 213 subjects of both genders between 20 to 70 years of age participated in this study from March 2018 to December 2019 at Smt. Kashibai Navale Medical College and General Hospital (SKNMCGH) in Pune, India. The volunteers were categorized according to their glycemic status as control (n= 51 Euglycemic) and T2DM (n= 162). The short-term ECG signal in the resting and after an orthostatic challenge was recorded. The HRV indices were extracted from the ECG signal as per HRV-Taskforce guidelines.

RESULTS

We observed a significant difference in time, frequency, and non-linear resting HRV indices between the control and T2DM groups. A blunted autonomic response to an orthostatic challenge quantified by percentage difference was observed in T2DM compared to the control group. HRV patterns during rest and the orthostatic challenge were extracted by various machine learning algorithms. The classification and regression tree (CART) model has shown better performance among all the machine learning algorithms. It has shown an accuracy of 84.04%, the sensitivity of 89.51%, a specificity of 66.67%, with an Area Under Receiver Operating Characteristic Curve (AUC) of 0.78 compared to resting HRV alone with 75.12% accuracy, 86.42% sensitivity, 39.22% specificity, with an AUC of 0.63 for differentiating autonomic dysfunction in non-diabetic control and T2DM.

CONCLUSION

It was possible to develop a Classification and Regression Tree (CART) model to detect autonomic dysfunction. The technique of percentage difference between resting and orthostatic challenge HRV indicates the blunted autonomic response. The developed CART model can differentiate the autonomic dysfunction using both resting and orthostatic challenge HRV data compared to only resting HRV data in T2DM. Thus, monitoring HRV parameters using the CART model during rest and after orthostatic challenge may be a better alternative to detect autonomic dysfunction in T2DM as against only resting HRV.

Assessment of Autonomic Nervous System Dysfunction in the Early Phase of Infection With SARS-CoV-2 Virus

BACKGROUND

We are facing the outburst of coronavirus disease 2019 (COVID-19) defined as a serious, multisystem, disorder, including various neurological manifestations in its presentation. So far, autonomic dysfunction (AD) has not been reported in patients with COVID-19 infection.

AIM

Assessment of AD in the early phase of infection with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2 virus).

PATIENTS AND METHODS

We analyzed 116 PCR positive COVID-19 patients. After the exclusion of 41 patients with associate diseases (CADG), partitioned to patients with diabetes mellitus, hypertension, and syncope, the remaining patients were included into a severe group (45 patients with confirmed interstitial pneumonia) and mild group (30 patients). Basic cardiovascular autonomic reflex tests (CART) were performed, followed by beat-to-beat heart rate variability (HRV) and systolic and diastolic blood pressure variability (BPV) analysis, along with baroreceptor sensitivity (BRS). Non-linear analysis of HRV was provided by Poincare Plot. Results were compared to 77 sex and age-matched controls.

RESULTS

AD (sympathetic, parasympathetic, or both) in our study has been revealed in 51.5% of severe, 78.0% of mild COVID-19 patients, and the difference compared to healthy controls was significant (p = 0.018). Orthostatic hypotension has been established in 33.0% COVID-19 patients compared to 2.6% controls (p = 0.001). Most of the spectral parameters of HRV and BPV confirmed AD, most prominent in the severe COVID-19 group. BRS was significantly lower in all patients (severe, mild, CADG), indicating significant sudden cardiac death risk.

CONCLUSION

Cardiovascular autonomic neuropathy should be taken into account in COVID-19 patients' assessment. It can be an explanation for a variety of registered manifestations, enabling a comprehensive diagnostic approach and further treatment.

Cardiovascular autonomic neuropathy in diabetes: Pathophysiology, clinical assessment and implications

Cardiovascular autonomic neuropathy (CAN) is a debilitating condition that mainly occurs in long-standing type 2 diabetes patients but can manifest earlier, even before diabetes is diagnosed. CAN is a microvascular complication that results from lesions of the sympathetic and parasympathetic nerve fibers, which innervate the heart and blood vessels and promote alterations in cardiovascular autonomic control. The entire mechanism is still not elucidated, but several aspects of the pathophysiology of CAN have already been described, such as the production of advanced glycation end products, reactive oxygen species, nuclear factor kappa B, and pro-inflammatory cytokines. This microvascular complication is an important risk factor for silent myocardial ischemia, chronic kidney disease, myocardial dysfunction, major cardiovascular events, cardiac arrhythmias, and sudden death. It has also been suggested that, compared to other traditional cardiovascular risk factors, CAN progression may have a greater impact on cardiovascular disease development. However, CAN might be subclinical for several years, and a late diagnosis increases the mortality risk. The duration of the transition period from the subclinical to clinical stage remains unknown, but the progression of CAN is associated with a poor prognosis. Several tests can be used for CAN diagnosis, such as heart rate variability (HRV), cardiovascular autonomic reflex tests, and myocardial scintigraphy. Currently, it has already been described that CAN could be detected even during the subclinical stage through a reduction in HRV, which is a non-invasive test with a lower operating cost. Therefore, considering that diabetes mellitus is a global epidemic and that diabetic neuropathy is the most common chronic complication of diabetes, the early identification and treatment of CAN could be a key point to mitigate the morbidity and mortality associated with this long-lasting condition.

Cardiovascular autonomic neuropathy in people with type 2 diabetes mellitus; investigation of its association with classical cardiovascular risk factors using cardiovascular autonomic reflex tests: a cross-sectional study

Background

People with type 2 diabetes mellitus (DM) are at increased risk of cardiovascular disease (CVD). Cardiovascular autonomic neuropathy (CAN) is an underdiagnosed risk factor for CVD, which is prevalent among people with 2DM and can lead to CVD and CVD-related mortality. Little is known about the risk factors associated with CAN in type 2DM. Thus, the study was aimed to assess CAN using five cardiovascular autonomic reflex tests (represented by Ewing’s score) and explore the factors associated with CAN in people with type 2DM. The studied factors include traditional and serological CVD risk factors obtained from a fasting blood sample and cardiorespiratory fitness (CRF) obtained via attainment of the highest peak of volumes of O₂ (VO_2Peak).

Results

Univariate analysis revealed a significant positive correlation between resting systolic blood pressure (SBP) and Ewing’s score (r=0.47, p=.02) and an inverse correlation between VO_2Peak and Ewing’s score (r=−0.64, p=.001). Multivariate linear regression revealed that a significant model that included resting SBP and VO_2Peak explained 93.8% of Ewing’s score variance.

Conclusion

CAN was associated with two CVD parameters, including resting SBP and CRF, which may indicate the importance of controlling these two factors to prevent or reduce CAN in people with type 2DM.

[Screening of cardiac autonomic neuropathy in a group of adolescents and young adult Cameroonians with type 1 diabetes]

AIM

We aimed to describe cardiac autonomic neuropathy in a group of young Cameroonians type 1 diabetic patients.

PATIENTS AND METHODS

We conducted a descriptive cross-sectional study including consenting patients with type 1 diabetes and without any other comorbidity, who were followed-up at the type 1 diabetic children's clinic at the Yaoundé central hospital. Cardiac autonomic neuropathy was diagnosed and stage using the five functional tests described by Ewang et al., and the heart rate variability assessment.

RESULTS

We included 60 with a mean age of 18.6±4.9 years, 38.3% of female and a mean duration of diabetes of 5.9±5.1 years. Cardiac autonomic neuropathy was present in 96.7% of participants. Early, confirmed and severe cardiac autonomic neuropathy were found respectively in 8.3%, 86.7% and 1.7% of the patients. The most frequent clinical signs were exercise intolerance, alternating constipation and diarrhea and resting tachycardia.

CONCLUSION

Cardiac autonomic neuropathy is common in young patients with type 1 diabetes. It is important to integrate the assessment of cardiac autonomic reflexes in type 1 diabetic patients' follow-up.

Diabetic heart disease: A clinical update

Diabetes mellitus (DM) significantly increases the risk of heart disease, and DM-related healthcare expenditure is predominantly for the management of cardiovascular complications. Diabetic heart disease is a conglomeration of coronary artery disease (CAD), cardiac autonomic neuropathy (CAN), and diabetic cardiomyopathy (DCM). The Framingham study clearly showed a 2 to 4-fold excess risk of CAD in patients with DM. Pathogenic mechanisms, clinical presentation, and management options for DM-associated CAD are somewhat different from CAD among nondiabetics. Higher prevalence at a lower age and more aggressive disease in DM-associated CAD make diabetic individuals more vulnerable to premature death. Although common among diabetic individuals, CAN and DCM are often under-recognised and undiagnosed cardiac complications. Structural and functional alterations in the myocardial innervation related to uncontrolled diabetes result in damage to cardiac autonomic nerves, causing CAN. Similarly, damage to the cardiomyocytes from complex pathophysiological processes of uncontrolled DM results in DCM, a form of cardiomyopathy diagnosed in the absence of other causes for structural heart disease. Though optimal management of DM from early stages of the disease can reduce the risk of diabetic heart disease, it is often impractical in the real world due to many reasons. Therefore, it is imperative for every clinician involved in diabetes care to have a good understanding of the pathophysiology, clinical picture, diagnostic methods, and management of diabetes-related cardiac illness, to reduce morbidity and mortality among patients. This clinical review is to empower the global scientific fraternity with up-to-date knowledge on diabetic heart disease.

Relationship between cardiac autonomic neuropathy and cardio-metabolic risk profile in adults with type 1 diabetes

AIM

The present study aims to determine the prevalence and association of cardiac autonomic neuropathy (CAN) with some traditional cardio-metabolic risk factors in adults with type 1 diabetes (T1D).

MATERIAL AND METHODS

235 adults with T1D, divided into three groups according to diabetes duration, were recruited in this cross-sectional study from May 2017 till December 2018. Anthropometric parameters and blood pressure were measured. Lipids, liver enzymes, uric acid, creatinine, HbA1c and high sensitive C-reactive protein (hsCRP) were measured at fasting. Albumin/creatinine ratio (ACR) was measured in a first spot urine sample. Body composition was evaluated using bio-impedance analysis, Inbody720 (Biospace, USA). Advanced glycation end products (AGEs) were assessed by autofluorescence method, AGE Reader (Diagnoptics, The Netherlands). CAN was assessed by ANX-3.0 monitoring technology (ANSAR Medical Technologies, Inc., Philadelphia, PA), applying standard clinical tests. 2005 IDF and 2009 JIS definitions were used to define Metabolic Syndrome (MetS).

RESULTS

The prevalence of CAN was 23% and increased with diabetes duration. Sympathetic activity was independently related to age, albumin/creatinine ratio (ACR) and total body fat mass, and parasympathetic activity - to age and ACR. Elevated hsCRP, AGEs and body fat, diabetic retinopathy and nephropathy, as well as hypertension, dyslipidemia and metabolic syndrome were found to increase the risk of CAN in T1D.

CONCLUSION

CAN appears to be a common complication of T1D, especially with longer duration, and is found to be related to diabetic microvascular disease and metabolic syndrome components.

Differences and Similarities in Neuropathy in Type 1 and 2 Diabetes: A Systematic Review

Background: Diabetic neuropathy is defined as the dysfunction of the peripheral nervous system in diabetic patients. It is considered a microvascular complication of diabetes mellitus. Its presence is associated with increased morbidity and mortality. Although several studies have found alterations at somatic motor, sensory levels and at the level of autonomic nervous system in diabetic patients, there is not a systematic approach regarding the differences in neuropathy between the major variants of diabetes, e.g., type 1 and 2 diabetes at both neurological and molecular level. Data sources: we systematically (Medline, Scopus, and Cochrane databases) evaluated the literature related to the difference of neuropathy in type 1 and 2 diabetes, differences in molecular biomarkers. Study characteristics: seventeen articles were selected based on pre-defined eligibility criteria. Conclusions: both superficial sensitivity (primarily thermal sensitivity to cold) and deep sensitivity (such as vibratory sensitivity), have been reported mainly in type 2 diabetes. Cardiac autonomic neuropathy is one of the diabetic complications with the greatest impact at a clinical level but is nevertheless one of the most underdiagnosed. While for type 1 diabetes patients most neuropathy alterations have been reported for the Valsalva maneuver and for the lying-to-standing test, for type 2 diabetes patients, alterations have been reported for deep-breathing test and the Valsalva test. In addition, there is a greater sympathetic than parasympathetic impairment, as indicated by the screening tests for autonomic cardiac neuropathy. Regarding subclinical inflammation markers, patients with type 2 diabetes showed higher blood levels of inflammatory markers such as high-sensitivity C-reactive protein, proinflammatory cytokines IL-6, IL-18, soluble cell adhesion molecules and E-selectin and ICAM-1, than in type 1 diabetes patients. By contrast, the blood levels of adiponectin, an adipocyte-derived protein with multiple paracrine and endocrine activities (anti-inflammatory, insulin-sensitizing and proangiogenic effects) are higher in type 1 than in type 2 diabetic patients. This review provides new insights into the clinical differences in type 1 and 2 diabetes and provide future directions in this research field.

Carvedilol improves heart rate variability indices, biomarkers but not cardiac nerve density in streptozotocin-induced T2DM model of diabetic cardiac autonomic neuropathy

OBJECTIVES

There has been increasing recognition of the significant relationship between the autonomic nervous system and cardiovascular sequel in diabetes mellitus (DM) patients. Diabetic cardiac autonomic neuropathy (DCAN) still poses a treatment challenge in the clinical settings despite several research interventions. This study was designed to investigate the effect of carvedilol on experimentally induced DCAN in type 2 DM rat model.

METHODS

DCAN was induced in 42 Wistar rats using high fat diet (HFD) for eight weeks, thereafter streptozotocin (STZ) at 25 mg/kg daily for five days. DCAN features were then assessed using non-invasive time and frequency varying holter electrocardiogram (ECG), invasive biomarkers, cardiac histology and cardiac nerve density.

RESULTS

Carvedilol significantly ameliorated the effects of DCAN on noradrenaline (p=0.010) and advanced glycated end products (AGEs) (p<0.0001). Similarly, carvedilol reversed the reduction in levels of antioxidants, sorbitol dehydrogenase (SD) activity (p=0.009) nerve growth factors (p<0.0001) and choline acetyl-transferase (p=0.031) following DCAN induction. Furthermore, heart rate variability (HRV) indices which were also reduced with DCAN induction were also ameliorated by carvedilol. However, carvedilol had no significant effect on cardiac neuronal dystrophy and reduced cardiac nerve densities.

CONCLUSIONS

Carvedilol improves physiological HRV indices and biomarkers but not structural lesions. Early detection of DCAN and intervention with carvedilol may prevent progression of autonomic neurologic sequel.

The prevalence of cardiac autonomic neuropathy in prediabetes: a systematic review

AIMS/HYPOTHESIS

Cardiac autonomic neuropathy (CAN) is independently associated with silent myocardial ischaemia, major cardiovascular events, myocardial dysfunction and cardiovascular mortality. Several studies have highlighted the increased prevalence of CAN in prediabetes (impaired glucose tolerance and/or impaired fasting glucose). Considering the exponential rise of prediabetes, we aimed to determine the prevalence of CAN through a systematic literature review.

METHODS

This systematic review was registered with PROSPERO (CRD42019125447). An electronic literature search was performed using MEDLINE, EMBASE, PubMed, Web of Science, Scopus and Cochrane databases. Published full text, English language articles that provide CAN prevalence data of studies in individuals with prediabetes and aged over 18 years were included. Prevalence data for normal glucose tolerance and diabetes were also extracted from the selected articles, if present. All articles were screened by two independent reviewers using a priori criteria. Methodological quality and risk of bias were evaluated using a critical appraisal tool.

RESULTS

Database searches found 4500 articles; subsequently, 199 full text articles were screened, 11 of which fulfilled the inclusion criteria (4431 total participants, 1730 people with prediabetes, 1999 people with normal glucose tolerance [NGT] and 702 people with predominantly type 2 diabetes). Six of the selected studies reported definite CAN prevalence data (9-39%). Only a single large population-based study by Ziegler et al (KORA S4 study, 1332 participants) determined definite CAN based on two or more positive autonomic function tests (AFTs), with a mean prevalence of 9% in all prediabetes groups (isolated impaired glucose tolerance 5.9%; isolated impaired fasting glucose 8.1%; impaired fasting glucose plus impaired glucose tolerance 11.4%), which was higher than NGT (4.5%). This study is most likely to provide a reliable population-specific estimate of CAN in prediabetes. There was a higher than expected prevalence of CAN in prediabetes (9-38%) when compared with normal glucose tolerance (0-18%) within the same studies (n = 8). There was a wide prevalence of possible CAN based on one positive AFT (n = 5). There was heterogeneity between the studies with variations in the definition of CAN, methodology and characteristics of the populations, which likely contributed to the diversity of prevalence estimates. The overall risk of bias was low.

CONCLUSIONS/INTERPRETATION

There is a higher than expected prevalence of CAN in prediabetes. Early detection of CAN in prediabetes through population screening needs careful consideration in view of the excess morbidity and mortality risk associated with this condition. Graphical abstract.

Assessment of sudomotor function in hypertensive with/without type-2 diabetes patients using SUDOSCAN: An electrophysiological study

Objective

Electrochemical skin conductance (ESC) test is a simple and non-invasive screening test can detect dysfunction of the peripheral sudomotor, and indirectly estimates the function of cardiac autonomic nerves. This study aimed to assess the ESC values in hypertensive patients with/without type-2 diabetes by using SUDOSCAN technology. Moreover, this study evaluated the role of cardiometabolic risk factors on the results of ESC test.

Methods

This cross-sectional study was carried on three groups of participants, including healthy subjects (Group I, n = 49), hypertensive without type-2 diabetes (Group II, n = 75) patients, and hypertensive with type-2 diabetes (Group III, n = 76) patients. Body mass index (BMI), blood pressure (systolic, diastolic and pulse pressure index), fasting serum glucose, and lipid profile were determined. ESC test as a measurement sudomotor function was determined by applying a small direct current at low voltage to hands and feet sensor plates through SUDOSCAN device.

Results

ESC values of the peripheral sudomotor nerves in the Group II and III patients were significantly lower than the corresponding values of Group I. SUDOSCAN results of Group II and III. Significant discriminators of cardiac autonomic neuropathy (≥30 score) that determined by the area under the curve (AUC) with 95% confidence interval (95% C.I.) were, duration of the disease, BMI, and mean blood pressure in Group II, while the duration of the disease and the BMI were significant discriminators in Group III.

Conclusions

SUDOSCAN is a simple, useful device, which can detect the impairment of peripheral autonomic small nerve fibers and the risk of cardiac autonomic neuropathy in hypertension. Moreover, the duration of the disease and the associated cardiometabolic risk factors are important predictors of significant SUDOSCAN findings.

Significance

ESC test is useful in detecting subclinical neuropathy in hypertensive patients as well as in type 2 diabetes.

Assessment of sudomotor function in hypertensive with/without type-2 diabetes patients using SUDOSCAN: An electrophysiological study

•

SUDOSCAN is a simple non-invasive device that can assess the sudomotor nerves.

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Hypertensive patients have sub-clinical impairment of peripheral and autonomic nerve fibers function.

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Cardio-metabolic risk factors are important discriminators of abnormal SUDOSCAN data.

Objective

Electrochemical skin conductance (ESC) test is a simple and non-invasive screening test can detect dysfunction of the peripheral sudomotor, and indirectly estimates the function of cardiac autonomic nerves. This study aimed to assess the ESC values in hypertensive patients with/without type-2 diabetes by using SUDOSCAN technology. Moreover, this study evaluated the role of cardiometabolic risk factors on the results of ESC test.

Methods

This cross-sectional study was carried on three groups of participants, including healthy subjects (Group I, n = 49), hypertensive without type-2 diabetes (Group II, n = 75) patients, and hypertensive with type-2 diabetes (Group III, n = 76) patients. Body mass index (BMI), blood pressure (systolic, diastolic and pulse pressure index), fasting serum glucose, and lipid profile were determined. ESC test as a measurement sudomotor function was determined by applying a small direct current at low voltage to hands and feet sensor plates through SUDOSCAN device.

Results

ESC values of the peripheral sudomotor nerves in the Group II and III patients were significantly lower than the corresponding values of Group I. SUDOSCAN results of Group II and III. Significant discriminators of cardiac autonomic neuropathy (≥30 score) that determined by the area under the curve (AUC) with 95% confidence interval (95% C.I.) were, duration of the disease, BMI, and mean blood pressure in Group II, while the duration of the disease and the BMI were significant discriminators in Group III.

Conclusions

SUDOSCAN is a simple, useful device, which can detect the impairment of peripheral autonomic small nerve fibers and the risk of cardiac autonomic neuropathy in hypertension. Moreover, the duration of the disease and the associated cardiometabolic risk factors are important predictors of significant SUDOSCAN findings.

Significance

ESC test is useful in detecting subclinical neuropathy in hypertensive patients as well as in type 2 diabetes.

Assessment of Autonomic Nervous System Dysfunction in the Early Phase of Infection With SARS-CoV-2 Virus

BACKGROUND

We are facing the outburst of coronavirus disease 2019 (COVID-19) defined as a serious, multisystem, disorder, including various neurological manifestations in its presentation. So far, autonomic dysfunction (AD) has not been reported in patients with COVID-19 infection.

AIM

Assessment of AD in the early phase of infection with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2 virus).

PATIENTS AND METHODS

We analyzed 116 PCR positive COVID-19 patients. After the exclusion of 41 patients with associate diseases (CADG), partitioned to patients with diabetes mellitus, hypertension, and syncope, the remaining patients were included into a severe group (45 patients with confirmed interstitial pneumonia) and mild group (30 patients). Basic cardiovascular autonomic reflex tests (CART) were performed, followed by beat-to-beat heart rate variability (HRV) and systolic and diastolic blood pressure variability (BPV) analysis, along with baroreceptor sensitivity (BRS). Non-linear analysis of HRV was provided by Poincare Plot. Results were compared to 77 sex and age-matched controls.

RESULTS

AD (sympathetic, parasympathetic, or both) in our study has been revealed in 51.5% of severe, 78.0% of mild COVID-19 patients, and the difference compared to healthy controls was significant (p = 0.018). Orthostatic hypotension has been established in 33.0% COVID-19 patients compared to 2.6% controls (p = 0.001). Most of the spectral parameters of HRV and BPV confirmed AD, most prominent in the severe COVID-19 group. BRS was significantly lower in all patients (severe, mild, CADG), indicating significant sudden cardiac death risk.

CONCLUSION

Cardiovascular autonomic neuropathy should be taken into account in COVID-19 patients' assessment. It can be an explanation for a variety of registered manifestations, enabling a comprehensive diagnostic approach and further treatment.

Myocardial ischaemia reperfusion injury and cardioprotection in the presence of sensory neuropathy: Therapeutic options

During the last decades, mortality from acute myocardial infarction has been dramatically reduced. However, the incidence of post-infarction heart failure is still increasing. Cardioprotection by ischaemic conditioning had been discovered more than three decades ago. Its clinical translation, however, is still an unmet need. This is mainly due to the disrupted cardioprotective signalling pathways in the presence of different cardiovascular risk factors, co-morbidities and the medication being taken. Sensory neuropathy is one of the co-morbidities that has been shown to interfere with cardioprotection. In the present review, we summarize the diverse aetiology of sensory neuropathies and the mechanisms by which these neuropathies may interfere with ischaemic heart disease and cardioprotective signalling. Finally, we suggest future therapeutic options targeting both ischaemic heart and sensory neuropathy simultaneously. LINKED ARTICLES: This article is part of a themed issue on Risk factors, comorbidities, and comedications in cardioprotection. To view the other articles in this section visit http://onlinelibrary.wiley.com/doi/10.1111/bph.v177.23/issuetoc.

The relationship between QT interval indices with cardiac autonomic neuropathy in diabetic patients: a case control study

BACKGROUND

Long QT interval (QT) and abnormal QT dispersion (QTd) are associated with sudden death. The relationship between cardiac autonomic neuropathy (CAN) and QT indices in type 2 diabetic patients were investigated.

METHODS

Totally 130 diabetic subjects (mean age 50.87 ± 13.9 years) were included (70 individuals with and 60 individuals without CAN). All participants had sinus cardiac rhythm. The patients who had diseases or take drugs that cause orthostatic hypotension (OH), cardiac arrhythmia and QT prolongation were excluded. After interview and examination, standard and continuous ECG was taken in supine position with deep breathing and standing up position. CAN diagnosis was based on Ewing's tests. QT, QT corrected (QTc), minimum QT (QT min), maximum QT (QT max) and mean ± SD of QT (QT mean) and QTd were assessed from standard ECG. QTc was calculated by Bazett's formula from V2 lead. QTc > 440 ms in men and QTc > 460 ms in women and QTd > 80 ms were considered abnormal.

RESULTS

In patients with CAN, 21.5% were symptomatic. The prevalence of abnormal QTc and QTd was 11.3% and 28.7%, respectively. There was no significant difference between the patients with or without CAN in terms of long QTc and abnormal QTd. However, the mean ± SD of QT max, QT mean and QTd was higher in the patients with CAN (P value < 0.03). The used cut points for QTc and QTd have high specificity (79% for both) and low sensitivity (30% and 37%, respectively). To use QTc and QTd as screening test for CAN in T2DM patients, the cutoff points 380 and 550 ms are suggested, respectively.

CONCLUSION

The prevalence of asymptomatic CAN was 3.7 times that of symptomatic CAN. In patients with CAN the QT max, QT mean and QTd were higher than those without CAN. There was no association between CAN and long QTc and abnormal QTd.

Neural tone and cardio-renal outcomes in patients with type 2 diabetes mellitus: a review of the literature with a focus on SGLT2 inhibitors

Recent clinical trials involving the systemic effects of sodium-glucose cotransporter 2 inhibitors (SGLT2i) have revealed beneficial outcomes pertaining to the microvascular sequelae of type 2 diabetes mellitus (T2DM) such as nephropathy, as well as macrovascular effects such as major adverse cardiovascular effects (MACE). Such findings have spurred the elevation of these agents to level A-tiers of recommendation within clinical guidelines addressing the management of complicated T2DM. While the mechanisms of SGLTi (-flozin drugs) are still being elucidated, a paucity of data exists within the literature appraising the role of neuromodulation and associated mechanisms in the aforementioned outcome studies. Given the role of the nervous system in orchestrating the pathologic processes that hamper cardio-renal status, insight into this topic offers an expanded perspective on T2DM. In this review we investigate the mechanisms by which SGLTi improve cardio-renal function in T2DM patients with emphases on neural tone and nervous system physiology.

Baroreflex sensitivity with different lags and random forests for staging cardiovascular autonomic neuropathy in subjects with diabetes

Impaired baroreflex sensitivity (BRS) may indicate cardiovascular autonomic neuropathy (CAN), which often remains undiagnosed during the initial course of diabetes mellitus. The baroreflex mechanism can be considered negative feedback because of baroreflex delay, the time delay between a change in blood pressure and the counteracting heart rate response. This work sought to analyze BRS considering lags from 1 to 10 RR intervals. We hypothesized that diabetic patients with subclinical CAN (SCAN) have a detectable delay in autonomic nervous system activity and that this would differ from patients without CAN (NCAN) and with established CAN (ECAN). In the first stage, 30 patients were included in an exploratory analysis using the Principal Component Analysis. Six indexes related to the BRS delay were proposed and considered significant for staging diabetic patients. Three indexes allowed for the differentiating of patients with and without CAN, and three indexes distinguished subjects with SCAN from subjects with NCAN or ECAN. Then, in the second stage, a random forest model was developed with 72 subjects, using the variables selected in the first stage. It was possible to detect SCAN, and to point out those subjects with the potential to change the CAN stage, allowing for the tracking of CAN progression. The model achieved a sensitivity of 96% and specificity of 100% to detect SCAN. Thus, the BRS analysis considering delayed reaction in the dynamics of heart rate variability may contribute to an accurate screening tool to staging CAN, in addition to indicating patients with most insidious disease progress.