Cardiac autonomic neuropathy predicts cardiovascular morbidity and mortality in type 1 diabetic patients with diabetic nephropathy

Diabetic kidney disease and cardiac autonomic neuropathy: insights on exercise rehabilitation

Patients with Diabetic Kidney Disease (DKD) suffer from various complications of diabetes mellitus, including autonomic neuropathy. Cardiac autonomic nervous system dysfunction is a common disorder in patients with diabetes mellitus and Chronic Kidney Disease (CKD), and is associated with an increased risk of arrhythmias and cardiovascular morbidity and mortality. Although the effects of exercise training have been thoroughly studied in different patient populations with CKD or diabetes mellitus, few studies have investigated the effects of exercise on cardiac autonomic nervous system activity in patients with DKD. This narrative review aims to summarize the evidence regarding the effects of exercise training on cardiac autonomic nervous system modulation in DKD patients.

Sex Differences in the Association Between Cardiovascular Autonomic Neuropathy and Mortality in Patients With Type 2 Diabetes: The ACCORD Study

BACKGROUND

Cardiovascular autonomic neuropathy (CAN) is a severe complication of type 2 diabetes. Significant sex-related differences have been observed in type 2 diabetes consequences such as mortality. However, the effect of sex on the association between CAN and mortality in patients with type 2 diabetes is currently unknown.

METHODS AND RESULTS

We assessed 7866 participants in the ACCORD (Action to Control Cardiovascular Risk in Diabetes) trial, including 4730 men and 3136 women. CAN was diagnosed using a combination of heart rate variability and QT interval index, which has 3 different definitions. There were 1364 cases of all-cause mortality and 452 cases of cardiovascular disease mortality during a median follow-up of 9.7 years. We used multivariable Cox regression models to assess the association between different CAN definitions and mortality. In women, various CAN measures were statistically significant associated with an increased risk of all-cause mortality (CAN1: hazard ratio [HR], 1.64 [95% CI, 1.28-2.09]; CAN2: HR, 1.58 [95% CI, 1.17-2.15]; CAN3: HR, 1.78 [95% CI, 1.20-2.65]) and mortality (CAN1: HR, 2.25 [95% CI, 1.44-3.52]; CAN 2: HR, 2.22 [95% CI, 1.28-3.87]; CAN3: HR, 3.31 [95% CI, 1.67-6.57]). CAN was not significantly associated with mortality in men. A significant multiplicative interaction of CAN and sex was observed on both mortality outcomes (P<0.01).

CONCLUSIONS

Significant sex-related differences were observed in CAN and its associated mortality. In terms of mortality risk prevention, CAN should be given greater consideration in women with type 2 diabetes.

Inflammatory Markers and Measures of Cardiovascular Autonomic Neuropathy in Type 1 Diabetes

BACKGROUND

Cardiovascular autonomic neuropathy (CAN) and inflammation predict more severe outcomes in type 1 diabetes (T1D). However, the link between CAN and inflammation in T1D remains unclear. We examined associations between CAN measures and inflammatory biomarkers in individuals with T1D.

METHODS AND RESULTS

In a cross-sectional study, we measured cardiovascular autonomic reflex tests and heart rate variability (established CAN measures) and a panel of 39 inflammatory biomarkers, including soluble urokinase plasminogen activator receptor (suPAR), in T1D participants of the TINSAL-T1DN (Targeting Inflammation with Salsalate in Individuals with T1D Neuropathy) trial (n=57, discovery), and the PERL (Preventing Early Renal Loss in Diabetes) trial (n=468, validation). Amongst 39 inflammatory biomarkers measured in TINSAL-T1DN, suPAR levels had the strongest negative correlations with CAN measures: expiration/inspiration (r=-0.48), Valsalva (r=-0.28), 30:15 (r=-0.37), SD of the normal RR interval (r=-0.37), and root mean square of differences of successive RR intervals (r=-0.31) (all P<0.05). Findings were validated in PERL. In unadjusted analyses, median suPAR levels significantly differed between the lowest and highest SD of the normal RR interval tertiles (3.79 versus 3.12 ng/mL, P<0.001) and root mean square of differences of successive RR intervals (3.76 versus 3.17 ng/mL, P<0.001). After adjusting for covariates (age, sex, hemoglobin A1c, and estimated glomerular filtration rate), median suPAR values remained significantly elevated in the lowest tertiles of SD of the normal RR interval (P=0.004) and root mean square of differences of successive RR intervals (P=0.006).

CONCLUSIONS

Amongst several inflammatory biomarkers, suPAR, an immune-mediated glycoprotein, has a singular association with CAN measures. The potential of targeting suPAR as a disease-modifying approach for CAN in T1D warrants further exploration.

REGISTRATION

URL: https://www.clinicaltrials.gov; Unique identifiers: NCT02936843, NCT02017171.

Whole Gut Motility Patterns in Patients with Chronic Nausea and Vomiting

Background/Objectives: Chronic nausea and vomiting (N/V) disorders are common in clinical practice. Our primary aim was to compare total and segmental gastrointestinal transit times as well as gastric contraction patterns in patients with chronic N/V syndrome to those of healthy volunteers (HVs). In the patient group, our secondary aim was to explore how symptoms and motility patterns were affected by a serotonin HT4 receptor agonist (Prucalopride). Methods: Patients with chronic N/V syndrome and HVs underwent baseline assessment of regional gastrointestinal (GI) motility/transit using the Motilis 3D-Transit system. Patients were then treated with Prucalopride 2 mg daily for 28 days, with the 3D-transit examination repeated within 10-20 days after treatment onset. Two self-administered questionnaires (the Gastrointestinal Symptom Rating Scale [GSRS] and Gastroparesis Cardinal Symptom Index [GCSI]) were used to assess patients' symptoms. Results: A total of 19 patients (13 F; median age 25 years (IQR 22-39) and 55 HVs (25 F; median age 28 (24-35) were included. At baseline, no differences in regional GI transit times were found between groups. However, patients had a significantly lower gastric contraction amplitude than HVs (9 mmHg (IQR 8-11) vs. 12 (10-15: p < 0.001). In response to Prucalopride treatment, gastric emptying time was reduced from a median of 3.1 h to 1.6 h (p < 0.005). Further, the GCSI was significantly reduced from GCSI 3.0 (IQR 2.3-3.7) at baseline to GCSI 1.9 (IQR 1.3-3.2) with Prucalopride. Conclusions: Patients with chronic N/V syndrome have significantly lower gastric contraction amplitude than HVs and may symptomatically benefit from prokinetics. They do not, however, have evidence of panenteric dysmotility.

Cardiovascular autonomic neuropathy and the risk of diabetic kidney disease

Background

Cardiovascular autonomic neuropathy (CAN) is known to affect patients with diabetes mellitus (DM) and cause adverse renal outcomes. We aimed to analyze the association between CAN and diabetic kidney disease (DKD).

Method

We enrolled 254 DM patients (mean age, 56.7 ± 15.2 years; male: female ratio, 1.17:1) with 19 (7.5%) type 1 DM patients and 235 (92.5%) type 2 DM patients. All patients had undergone cardiovascular autonomic function tests between January 2019 and December 2021 in a tertiary hospital in Korea. Cardiovascular autonomic neuropathy was categorized as normal, early, or definite after measuring three heart rate variability parameters. Diabetic kidney disease refers to a persistently elevated urinary albumin-creatinine ratio (uACR ≥30 mg/g) or reduced estimated glomerular filtration rate (eGFR <60 mL/min/1.73 m2). Logistic and Cox regression analyses were performed.

Results

Patients with elevated uACR (n=107) and reduced eGFR (n=32) had a higher rate of definite CAN. After adjusting for covariates, definite CAN was associated with elevated uACR (OR=2.4, 95% CI 1.07-5.36) but not with reduced eGFR (OR=3.43, 95% CI 0.62-18.90). A total of 94 patients repeated uACR measurements within 2 years (mean follow-up, 586.3 ± 116.8 days). Both definite and early CAN were independent risk factors for elevated uACR (HR=8.61 and 8.35, respectively; both p<0.05). In addition, high-density lipoprotein cholesterol, ACE inhibitors/angiotensin receptor blockers and glucagon-like peptide-1 receptor agonists were independent protective factors for elevated uACR (HR=0.96, 0.25, and 0.07, respectively; all p<0.05).

Conclusion

Cardiovascular autonomic neuropathy is a potential indicator of DKD. Comprehensive management of DKD in the early stages of CAN may prevent microalbuminuria.

Sympathetic Nervous System and Atherosclerosis

Atherosclerosis is characterized by the narrowing of the arterial lumen due to subendothelial lipid accumulation, with hypercholesterolemia being a major risk factor. Despite the recent advances in effective lipid-lowering therapies, atherosclerosis remains the leading cause of mortality globally, highlighting the need for additional therapeutic strategies. Accumulating evidence suggests that the sympathetic nervous system plays an important role in atherosclerosis. In this article, we reviewed the sympathetic innervation in the vasculature, norepinephrine synthesis and metabolism, sympathetic activity measurement, and common signaling pathways of sympathetic activation. The focus of this paper was to review the effectiveness of pharmacological antagonists or agonists of adrenoceptors (α1, α2, β1, β2, and β3) and renal denervation on atherosclerosis. All five types of adrenoceptors are present in arterial blood vessels. α1 blockers inhibit atherosclerosis but increase the risk of heart failure while α2 agonism may protect against atherosclerosis and newer generations of β blockers and β3 agonists are promising therapies against atherosclerosis; however, new randomized controlled trials are warranted to investigate the effectiveness of these therapies in atherosclerosis inhibition and cardiovascular risk reduction in the future. The role of renal denervation in atherosclerosis inhibition in humans is yet to be established.

The association of insulin resistance measured through the estimated glucose disposal rate with predictors of micro-and macrovascular complications in patients with type 1 diabetes

BACKGROUND AND AIM

Insulin resistance (IR) is associated with a higher rate of type 1 diabetes (T1D) complications. We aimed to examine the relationship between estimated glucose disposal rate (eGDR), a readily available marker of IR in clinical practice and early predictor biomarkers of macrovascular and microvascular complications in patients with T1D.

DESIGN

A cross-sectional study.

METHODS

A total of 165 consecutive patients with T1D free of cardiovascular, eye, and renal complications were included in the study from 2016 to 2020. Participants were characterized as insulin resistant if their eGDR value was ≤ 8 mg/kg/min. Pulse wave velocity (PWV) and global longitudinal strain (GLS) were used as surrogates for subclinical atherosclerosis and left ventricular systolic dysfunction (LVSD), respectively. Four previously standardized tests based on the calculation of heart rate variability (HRV) were used to evaluate subclinical cardiac autonomic neuropathy (CAN). Early nephropathy was assessed by assessing urinary albumin to creatinine ratio (ACR).

RESULTS

The population sample (n = 165) included a majority of female patients (63%) and had a median age of 32 years (24-43), median disease duration of 14 years ( ± 9.5-21.5), a median BMI value of 23.7 kg/m² (21.4-26.6), an HbA1C of 7.2% (6.7-8.2) and median eGDR (lower values indicate higher insulin resistance) of 9.2 mg/kg/min (8.2-9.9), while 21.8% (n = 36) of the participants were characterized as insulin resistant. After adjustment for age, gender, and the duration of diabetes, the presence of IR was significantly associated with higher prevalence of subclinical atherosclerosis (OR:2.59, 95% CI: 1.06-6.30, p = 0.036), CAN (OR:3.07, 95% CI: 1.02-9.32, p = 0.047) and subclinical LVSD (OR: 4.9, 95% CI: 1.94-12.79, p = 0.001). No association was shown with ACR.

CONCLUSIONS

In patients with T1D, insulin resistance, as measured by eGDR, correlates well with early CVD predictors and CAN. These associations appear independent of the effects of gender, aging, and disease duration.

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.

Cardiac autonomic dysfunction and risk of incident stroke among adults with type 2 diabetes

Introduction:

There is a dearth of data on the association between cardiac autonomic neuropathy (CAN) with incident stroke among individuals with diabetes mellitus. We evaluated this association in a large sample of adults with type 2 diabetes.

Patients and methods:

Participants with type 2 diabetes from the Action to Control Cardiovascular Risk in Diabetes (ACCORD) study without atherosclerotic cardiovascular disease at baseline were included. CAN was assessed at baseline by heart rate variability (HRV) indices and QT index (QTI) calculated from 10-s resting electrocardiograms. HRV was assessed using standard deviation of all normal-to-normal R-Rs intervals (SDNN) and root mean square of successive differences between normal-to-normal R-R intervals (rMSSD). CAN was defined based on several composite measures of SDNN, QTI, resting heart rate and peripheral neuropathy. We used Cox proportional hazards regression to generate hazard ratios (HR) and 95% confidence intervals (CI) for incident stroke in relation to CAN.

Results:

A total of 3493 participants (mean age 62.2 years, 44.5% women, 62.9% White) were included. Over a median follow-up of 5.0 years, 50 stroke cases occurred (incidence rate 3.0/1000 person-years [95% CI 2.2–3.9]). After adjusting for confounders, low HRV was associated with a higher risk of stroke (HR of 2.20 [95% CI 1.23–3.93] and 1.88 [95% CI 1.04–3.41] for low SDNN and rMSSD, respectively). Participants with CAN (defined as lowest quartile of SDNN and highest quartiles of QTI and heart rate) had a 5.7-fold greater risk of stroke (HR 5.70, 95% CI 2.49–13.08).

Discussion and conclusion:

CAN was independently associated with an increased risk of incident stroke in a large cohort of adults with type 2 diabetes.

Renal hemodynamic dysfunction and neuropathy in longstanding type 1 diabetes: Results from the Canadian study of longevity in type 1 diabetes

AIMS

To determine the relationship between renal hemodynamic function and neuropathy in adults with ≥50-years of type 1 diabetes (T1D) compared to nondiabetic controls.

METHODS

Glomerular filtration rate (GFR, inulin), effective renal plasma flow (ERPF, p-aminohippurate), modified Toronto Clinical Neuropathy Score (mTCNS), corneal confocal microscopy, nerve conduction, and heart rate variability (autonomic function) were measured; afferent (RA) and efferent (RE) arteriolar resistances were estimated using the Gomez equations in 74 participants with T1D and in 75 controls. Diabetic kidney disease (DKD) non-resistors were defined by eGFRMDRD < 60 ml/min/1.73 m2 or 24-h urine albumin excretion >30 mg/day. Linear regression was applied to examine the relationships between renal function (dependent variable) and neuropathy measures (independent variable), adjusted for age, sex, HbA1c, systolic blood pressure, low density lipoprotein cholesterol, and 24-h urine albumin to creatinine ratio.

RESULTS

Higher mTCNS associated with lower renal blood flow (β ± SE:-9.29 ± 4.20, p = 0.03) and greater RE (β ± SE:32.97 ± 15.43, p = 0.04) in participants with T1D, but not in controls. DKD non-resistors had a higher mTCNS and worse measures of corneal nerve morphology compared to those without DKD. Renal hemodynamic parameters did not associate with autonomic nerve function.

CONCLUSIONS

Although neurological dysfunction in the presence of diabetes may contribute to impaired renal blood flow resulting in ischemic injury in patients with T1D, early autonomic dysfunction does not appear to be associated with kidney function changes.

Cardiac Autonomic Nerve Dysfunction Predicts Incident Retinopathy and Early Kidney Dysfunction in Adolescents With Type 1 Diabetes

OBJECTIVE

Cardiac autonomic neuropathy (CAN) may contribute to vascular complications in diabetes. We hypothesized that adolescents with CAN are at greater risk of diabetic retinopathy and early kidney dysfunction.

RESEARCH DESIGN AND METHODS

In this prospective longitudinal study of 725 adolescents with type 1 diabetes without retinopathy and albuminuria at baseline, early CAN was defined as one or more abnormalities in seven heart rate tests derived from a 10-min electrocardiogram. Retinopathy was defined as the presence of one or more microaneurysms, early kidney dysfunction as an albumin excretion rate (AER) >7.5 μg/min, and albuminuria as an AER >20 μg/min. Multivariable generalized estimating equations were used to examine the association between CAN and retinopathy or early kidney dysfunction. Cox proportional hazards regression analysis was used to assess cumulative risks of incident retinopathy and albuminuria.

RESULTS

At baseline, the mean age of the sample was 13.6 ± 2.6 years, 52% were male, and mean diabetes duration was 6.1 ± 3.3 years. Over a median follow-up of 3.8 (interquartile range 2.2-7.5) years, the complication rate 27% for retinopathy, 16% for early kidney dysfunction, and 3% for albuminuria. The mean study HbA1c was 72.3 ± 16 mmol/mmol (8.6 ± 1.4%). CAN predicted incident retinopathy (odds ratio 2.0 [95% CI 1.4, 2.9]) and early kidney dysfunction (1.4 [1.0, 2.0]) after adjusting for HbA1c and diabetes duration. CAN also predicted retinopathy (hazard ratio 1.57 [95% CI 1.09, 2.26]) and albuminuria (2.30 [1.05, 5.04]) independently of HbA1c.

CONCLUSIONS

CAN predicted incident retinopathy and kidney dysfunction in adolescents with type 1 diabetes, likely reflecting autonomic microvascular dysregulation contributing to complications. Therefore, screening and interventions to reduce CAN may influence the risk of complications.

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.

Retracted: Association of QT interval indices with cardiac autonomic neuropathy in diabetic patients

Background. Cardiovascular autonomic neuropathy (CAN) is a severely debilitating yet underdiagnosed condition in patients with diabetes mellitus. The prevalence can range from 2.5% (based on the primary prevention cohort in the Diabetes Control and Complications Trial) to as high as 90% of diabetic patients. Clinical manifestations range from orthostasis to myocardial infarction. The diagnosis is made using multiple autonomic function tests to assess both sympathetic and parasympathetic function. This study was conducted to assess the relationship between Cardiac autonomic neuropathy and QT interval. Material and methods. This was a cross-sectional study conducted in 100 patients attending a tertiary care hospital in India. Deep breathing test, Valsalva ratio, immediate heart rate response to standing 30 : 15, BP rise with sustained hand grip and postural hypotension were evaluated. Scoring was done for cardiac autonomic neuropathy. QT interval and QTc interval were determined and association with CAN was obtained. Results. Out of 100 type 2 diabetic patients, 60% were males and 40% were females. 25 patients having no cardiac autonomic neuropathy and had no prolonged QTc interval. While, 75 patients had QTc prolonged were associated with early and severe CAN cardiac autonomic neuropathy. The prolonged QTc was significantly associated with CAN in diabetic patients when compared without CAN and controls (P < 0.0001). The grading score for CAD showed that 75% cases were having score > 2 were 25% of cases had score < 2. Out of 75 patients 44 were between score 2–4 and 31 were above score 4. A significant association between QTc and Diabetic CAN patients observed when compared non CAN and controls. Conclusions. Diabetic cardiac autonomic neuropathy is associated with increase in prolongation of QTc intervals. Hence, there is need for regular checkup of autonomic nervous system in diabetic patient to prevent further complications.

Role of autonomic system imbalance in neurogenic pulmonary oedema

Neurogenic pulmonary oedema (NPE) is a life-threatening complication that develops rapidly and dramatically after an injury to the central nervous system (CNS). The autonomic system imbalance produced by severe brain damage may play an important role in the development of NPE. Activation of the sympathetic nervous system and inhibition of the vagus nerve system are essential prerequisites for autonomic system imbalance. The more severe the damage, the more pronounced the phenomenon. Sympathetic hyperactivity is associated with increased release of catecholamines from peripheral sympathetic nerve endings, which can cause dramatic changes in haemodynamics and cause pulmonary oedema. On the other hand, the abnormal inflammatory response caused by vagus nerve inhibition may also play an important role in the pathogenesis of NPE. The perspective of autonomic system imbalance seems to perfectly integrate the existing pathogenesis of NPE and can explain the entire development progression of NPE.

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.

The association between physical activity time and neuropathy in longstanding type 1 diabetes: A cross-sectional analysis of the Canadian study of longevity in type 1 diabetes

AIM

Physical activity (PA) is recommended to improve glycemic control in T1D; however, the effect of PA on distal symmetric polyneuropathy (DSPN) and cardiac autonomic function in longstanding T1D is unknown.

METHODS

Data from 75 participants were collected as part of the Canadian Study of Longevity in T1D. Participants completed a physical exam, medical history, extensive complications phenotyping and reported their daily PA from the preceding 12-months. Pearson and Spearman correlations were used to assess PA time and complications variables. Linear regression was used to test associations between PA time, neurological and electrophysiological measures. Univariable regression was used to indicate the change in the given independent variables associated with a 30-min increase in PA per week.

RESULTS

Participants were 66 ± 8 years old with diabetes duration of 54 [52,58] years, HbA_1c was 7.3 ± 0.8, 65(89%) had DSPN. Weekly PA time was 156 ± 132 min, and 35(47%) reported ≧150 min/week. Participants with DSPN reported lower PA time compared to individuals without DSPN (141 ± 124 min/week vs. 258 ± 129 min/week; p = 0.015). PA time was associated with better cooling detection threshold (r = 0.24; p = 0.043), peroneal and sural amplitude (r = 0.36; p = 0.0017, r_s = 0.26; p = 0.024) and conduction velocity (r_s = 0.28; p = 0.015, r = 0.23; p = 0.050). Linear regression adjusting for age and HbA1c, showed that for each 30-min of PA there was a 0.09mv higher peroneal amplitude (p = 0.032) and 0.048 ms lower peroneal F-wave latency (p = 0.022).

CONCLUSION

In longstanding T1D, PA time is associated with superior large nerve fibre function in the lower limbs and some better measures of small nerve fibre function.

Cardiac Autonomic Neuropathy and Risk of Incident Heart Failure Among Adults with Type 2 Diabetes

AIMS

Community-based data on the association between cardiac autonomic neuropathy (CAN) and incident heart failure (HF) in type 2 diabetes are limited. We evaluated the association of CAN with incident HF in adults with type 2 diabetes.

METHODS AND RESULTS

This analysis included participants from the Action to Control Cardiovascular Risk in Diabetes (ACCORD) study without HF at baseline. CAN was assessed by electrocardiogram-based measures of heart rate variability (HRV) and QT interval index (QTI). HRV was measured using standard deviation of all normal-to-normal intervals (SDNN) and root mean square of successive differences between normal-to-normal intervals (rMSSD). CAN was defined using composite measures of the lowest quartile of SDNN and highest quartiles of QTI and heart rate. Multivariable Cox regression models were used to generate adjusted hazard ratios (aHR) for HF in relation to various CAN measures. A total of 7160 participants (mean age 62.3 [standard deviation 6.4] years, 40.8% women, 61.9% white) were included. Over a median follow-up of 4.9 years (interquartile range 4.0-5.7), 222 participants developed incident HF. After multivariable adjustment for relevant confounders, lower HRV as assessed by SDNN was associated with a higher risk of HF (aHR for the lowest vs highest quartile of SDNN: 1.70, 95% confidence interval [CI] 1.14-2.54). Participants with CAN (defined as lowest quartile of SDNN and highest quartiles of QTI and heart rate) had a 2.7-fold greater risk of HF (aHR 2.65, 95% CI 1.57-4.48).

CONCLUSIONS

In a large cohort of adults with type 2 diabetes, CAN was independently associated with higher risk of incident HF.

Cardiac autonomic neuropathy and risk of cardiovascular disease and mortality in type 1 and type 2 diabetes: a meta-analysis

We aimed to determine the prognostic association between cardiac autonomic neuropathy (CAN) and cardiovascular disease events (CVE) and mortality in type 1 and type 2 diabetes through a systematic review and meta-analysis. This systematic review and meta-analysis was registered with PROSPERO (CRD42020216305) and was conducted with Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) methodological criteria. CAN was defined on the basis of 1 (early/possible CAN) or ≥2 (definite CAN) positive autonomic function tests as per the Toronto Consensus guidelines. Studies included those with prospective CVE or mortality data. Methodological variables/risk of bias were assessed using ROBINS-I (Risk Of Bias In Non-randomized Studies - of Interventions) and RoB-2 (Risk-Of-Bias tool for randomized trials) appraisal tools. Electronic database searches yielded 18 467 articles; 84 articles were screened full-text, 26 articles fulfilled the inclusion criteria for quantitative synthesis. Sixteen studies from patients with (n=2875) and without (n=11 722) CAN demonstrated a pooled relative risk (RR) of 3.16 (95%CI 2.42 to 4.13; p<0.0001) of future CVE in favour of CAN. Nineteen studies provided all-cause mortality data from patients with (n=3679) and without (n=12 420) CAN, with a pooled RR of 3.17 (95%CI 2.11 to 4.78; p<0.0001) in favour of CAN. The risk of both future CVE and mortality was higher in type 1 compared with type 2 diabetes and with a definite CAN (vs possible CAN) diagnosis. Three studies were considered to have risk of serious bias. This study confirms the significant association between CAN and CVE and all-cause mortality. The implementation of population-based CAN screening will identify a subgroup with disproportionately higher cardiovascular and mortality risk that will allow for earlier targeted intervention.

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.

Assessment of Myocardial Dysfunction by Three-Dimensional Echocardiography Combined With Myocardial Contrast Echocardiography in Type 2 Diabetes Mellitus

Background: We aimed to explore the value of combining real-time three-dimensional echocardiography (RT-3DE) and myocardial contrast echocardiography (MCE) in the left ventricle (LV) evaluating myocardial dysfunction in type 2 diabetes mellitus (T2DM) patients.

Patients and Methods: A total of 58 T2DM patients and 32 healthy individuals were selected for this study. T2DM patients were further divided into T2DM without microvascular complications (n = 29) and T2DM with microvascular complications (n = 29) subgroups. All participants underwent RT-3DE and MCE. The standard deviation (SD) and the maximum time difference (Dif) of the time to the minimum systolic volume (Tmsv) of the left ventricle were measured by RT-3DE. MCE was performed to obtain the perfusion measurement of each segment of the ventricular wall, including acoustic intensity (A), flow velocity (β), and A·β.

Results: There were significant differences in all Tmsv indices except for Tmsv6-Dif among the three groups (all P < 0.05). After heart rate correction, all Tmsv indices of the T2DM with microvascular complications group were prolonged compared with the control group (all P < 0.05). The parameters of A, β, and A·β for overall segments showed a gradually decreasing trend in three groups, while the differences between the three groups were statistically significant (all P < 0.01). For segmental evaluation of MCE, the value of A, β, and A·β in all segments showed a decreasing trend and significantly differed among the three groups (all P < 0.05).

Conclusions: The RT-3DE and MCE can detect subclinical myocardial dysfunction and impaired myocardial microvascular perfusion. Left ventricular dyssynchrony occurred in T2DM patients with or without microvascular complications and was related to left ventricular dysfunction. Myocardial perfusion was reduced in T2DM patients, presenting as diffuse damage, which was aggravated by microvascular complications in other organs.

Association of physical activity metrics with indicators of cardiovascular function and control in children with and without type 1 diabetes

OBJECTIVE

Little is known about the role of physical activity accumulation in cardiovascular disease risk for children with type 1 diabetes. Improved insight to identify factors of influence in key health outcomes could be provided by considering the entire physical activity profile.

METHODS

Pulse wave velocity (PWV), augmentation index and heart rate variability (HRV) were assessed cross-sectionally in children with (n = 29, 12.1 ± 2.1 years) and without (n = 19, 12.1 ± 2.1 years) type 1 diabetes. Time spent sedentary and in each physical activity intensity, intensity gradient and average acceleration were derived from seven consecutive days of monitoring with wrist-worn accelerometry. Comparison between groups and influence of physical activity accumulation on cardiovascular metrics were explored with linear mixed models.

RESULTS

Diabetic children demonstrated a higher PWV and a greater volume of light physical activity (p < 0.01), a more negative intensity gradient (p < 0.01), a lower average acceleration and less time in bouted moderate-to-vigorous physical activity (MVPA; p < 0.05). Overall, intensity gradient was strongly correlated with average acceleration, MVPA and bouted MVPA (r² = 0.89, r² = 0.80, r² = 0.79, respectively; all p < 0.05), while average acceleration was correlated with MVPA and bouted MVPA (r² = 0.85, r² = 0.83, respectively; p < 0.05). Accounting for disease status, intensity gradient and average acceleration were significant predictors of HRV indices (p < 0.05) and PWV (p < 0.01, p < 0.05, respectively).

CONCLUSION

Overall, MVPA was most associated with central stiffness, highlighting the importance of meeting activity guidelines. Diabetic children demonstrated poorer cardiovascular health than their counterparts, likely attributable to a lower intensity and physical activity volume, identifying physical activity intensity as a key target for future interventions.

Arterial stiffness and microvascular disease in type 2 diabetes

BACKGROUND

The clustering of arterial stiffness with microvascular disease (MD) and their effects on the clinical outcome of patients with type 2 diabetes (T2D) remains not fully clarified.

METHODS

In a prospective study of 414 patients with T2D, we investigated the prognostic value of arterial stiffness and MD for clinical outcomes. Participants were assessed for the presence of MD (ie diabetic retinopathy, nephropathy and neuropathy) and arterial stiffness by pulse wave velocity (PWV) and followed-up for a median of 30 (range 1-60) months. The primary endpoint of the study was the composite endpoint of major adverse cardiovascular events, that is, cardiovascular and non-cardiovascular mortality and non-fatal myocardial infarction/stroke.

RESULTS

A total of 146 (35.3%) patients had evidence of MD at baseline. In cox regression models, MD and PWV were independently associated with the composite clinical endpoint; for MD hazard ratio (HR), 3.24, 95%CI, 1.10-9.54, P=.032, and for PWV HR, 1.20, 95%CI, 1.06-1.36, P=.004) after adjustment for traditional risk factors, and enhanced risk discrimination and reclassification. The subgroup of patients with MD and high PWV was associated with increased incidence of the composite clinical endpoint (20.9% vs 1.8% in those with no MD & low PWV, P=.001). Importantly, absence of MD at baseline was associated with no mortality events during the follow-up period. PWV at baseline was not associated with MD progression during follow-up.

CONCLUSIONS

These findings support that screening for arterial stiffness and MD in the routine clinical assessment of patients with T2D may enhance prognostication and cardiovascular risk reclassification.

Decreased glomerular filtration rate and increased albuminuria for identification of cardiovascular autonomic neuropathy in subjects with and without diabetes

OBJECTIVE

The purpose of this study was to determine the relationship between chronic kidney disease (CKD) and cardiovascular autonomic neuropathy (CAN).

RESEARCH DESIGN AND METHODS

From October 2008 to May 2011, we enrolled 218 patients with diabetes and 62 nondiabetic subjects. Heart rate variability was represented as the maximal heart rate minus the minimal heart rate (HR_max-min) during a one-minute deep breathing test. Normal, impaired cardiovascular autonomic function and CAN were defined as s HR_max-min > 15 beats/min, HR_max-min of 10-15 beats/min and HR_max-min < 10 beats/min, respectively. CKD was diagnosed if the estimated glomerular filtration rate (eGFR) was <60/min/1.73 m² or albuminuria.

RESULTS

In our sample, 19.4% of nondiabetic subjects and 49.5% of diabetic subjects had CKD. The prevalence of CAN was higher among patients with diabetes than among nondiabetic subjects (26.4 vs. 4.9%). A significant association was observed between eGFR and HR_max-min. CAN was independently associated with CKD with an adjusted odds ratio of 2.77 (95% CI, 1.15-6.68) in diabetic patients. A positive linear trend was observed for the odds of CAN with increasing CKD severity in diabetes. The areas under the curve (AUCs) for the predictive ability of eGFR for the risk of impaired cardiovascular autonomic function for nondiabetic group and CAN for the diabetic group were 0.734 and 0.703, respectively. Adding age, sex, body mass index, and albuminuria to the prediction model increased the AUCs to 0.852 and 0.791, respectively.

CONCLUSION

CKD is associated with the risk of CAN in both nondiabetic and diabetic subjects. eGFR and albuminuria improve the prediction of CAN.

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.

Autonomic neuropathies

Autonomic neuropathies represent a complex group of disorders that preferentially target autonomic fibers and can be classified as either acute/subacute or chronic in onset. Acute-onset autonomic neuropathies manifest with such conditions as paraneoplastic syndromes, Guillain-Barre syndrome, Sjögren syndrome, infection, or toxins/chemotherapy. When the presentation is acute, immune-mediated, and without a secondary cause, autoimmune autonomic ganglionopathy is likely, and should be considered for immunotherapy. Of the chronic-onset forms, diabetes is the most widespread and disabling, with autonomic impairment portending increased mortality and cardiac wall remodeling risk. Acquired light chain (AL) and transthyretin (TTR) amyloidosis represent two other key etiologies, with TTR amyloidosis now amenable to newly-approved gene-modifying therapies. The COMPASS-31 questionnaire is a validated outcome measure that can be used to monitor autonomic severity and track treatment response. Symptomatic treatments targeting orthostatic hypotension, among other symptoms, should be individualized and complement disease-modifying therapy, when possible.

Hyperoxia improves autonomic function in individuals with long-duration type 1 diabetes and macroalbuminuria

AIM

Acute oxygen inhalation and slow deep breathing improve measures of autonomic function transiently in individuals with short-duration type 1 diabetes. Our aims were to examine these interventions and changes in autonomic function in individuals with long-duration type 1 diabetes and to explore interactions with the presence of macroalbuminuria or existing cardiovascular autonomic neuropathy.

METHODS

Individuals with type 1 diabetes (n = 54) were exposed to acute oxygen inhalation, slow deep breathing and a combination of both (hereafter 'the combination'). Primary outcomes were change in baroreflex sensitivity and heart rate variability. Associations between changes in outcomes were evaluated using mixed effects models.

RESULTS

Mean age ± sd was 60 ± 10 years and diabetes duration was 38 ± 14 years. Changes are presented as per cent difference from baseline with 95% confidence intervals. Acute oxygen inhalation, slow deep breathing and the combination increased baroreflex sensitivity by 21 (10, 34)%, 32 (13, 53)% and 30 (10, 54)%, respectively. Acute oxygen inhalation trended towards increasing heart rate variability 8 (-1, 17)% (P = 0.056), and slow deep breathing and the combination increased heart rate variability by 33 (18, 49)% and 44 (27, 64)% respectively. Macroalbuminuria or cardiovascular autonomic neuropathy did not modify results.

CONCLUSION

Autonomic function is improved transiently in individuals with long-duration type 1 diabetes and normoalbuminuria or macroalbuminuria by acute oxygen inhalation and slow deep breathing. There is a risk of survival bias. Autonomic dysfunction might be a reversible condition, and hypoxia might represent a target of intervention.

Cardiovascular autonomic neuropathy: A silent killer with long reach

Cardiovascular autonomic neuropathy (CAN) is a common and deadly complication of diabetes mellitus, which is frequently overlooked in clinical practice due to its characteristic subtle presentation earlier in disease. Yet, timely detection of CAN may help implementation of tailored interventions to prevent its progression and mitigate the risk of associated complications, including cardiovascular disease (CVD), cardiac arrhythmias, myocardial dysfunction leading to congestive heart failure and all-cause mortality. This review highlights current CAN epidemiology trends, novel mechanisms linking CAN with other diabetes complications and current recommendations for diagnosis and management of the disease in the clinical setting.

Spectrum of diabetic neuropathies

The diabetic state results in neuropathy. The main causative mechanism is hyperglycemia, although microvascular involvement, hypertriglyceridemia, as well as genetic and immune mechanisms may be contributory. There is a growing spectrum of types of diabetic neuropathies that differ based on the type of fibers involved (e.g. myelinated, unmyelinated, autonomic, somatic), distribution of nerves involved, and mechanisms of neuropathy. The most common type is distal sensory neuropathy (DSN), which affects the distal ends of large myelinated fibers, more often sensory than motor, and is often asymptomatic. The next-most common is distal small fiber neuropathy (DSFN), which largely affects the unmyelinated fibers and carries the phenotype of burning feet syndrome. Diabetic autonomic neuropathy (DAN) occurs when widespread involvement of autonomic unmyelinated fibers occurs, and patients can be incapacitated with orthostatic hypotension as well as neurogenic bladder and bowel involvement. Radiculoplexus diabetic neuropathy causes proximal weakness and pain, usually in the lower extremity, and has a combination of immune, inflammatory, and vascular mechanisms. The nerve roots and plexus are involved. These patients present with proximal weakness of a subacute onset, often with severe pain and some autonomic failure. Finally, rapid and sustained reduction of blood glucose can result in treatment-induced diabetic neuropathy (TIND), which largely affects the sensory and autonomic fibers. This occurs if HbA1c is rapidly reduced within 3 months, and the likelihood is proportional to the original A1c and the size of the reduction.

Simultaneous Pancreas Kidney Transplantation Improves Cardiovascular Autonomic Neuropathy with Improved Valsalva Ratio as the Most Precocious Test

BACKGROUND

Simultaneous pancreas-kidney (SPK) transplantation is a proven option of treatment for patients with type 1 diabetes mellitus (T1DM) and related end-stage renal disease. There is discrepancy between the results of different studies about the impact of prolonged normalization of glucose metabolism achieved by SPK on the course of diabetic complications including severe forms of diabetic neuropathy. The objective of the study was to evaluate the prevalence of cardiovascular autonomic neuropathy (CAN) in patients undergoing SPK transplantation and its evolution 10 years after transplantation.

METHODS

Prospective study of 81 patients transplanted in a single center from year 2002 to 2015. Autonomic function was assessed using cardiovascular autonomic reflex tests (CARTs). CARTs were made before SPK transplantation and during the follow-up. Evolution of tests after SPK transplantation was evaluated by contrasting hypotheses (paired tests). Multiple testing was adjusted with the Benjamini-Hochberg procedure with a false discovery rate of 10%.

RESULTS

48 males and 33 females, mean age 37.4 ± 5.7 years, mean BMI 24.0 ± 3.4 kg/m², and mean duration of diabetes 25.5 ± 6.5 years, received SPK transplantation. Ten years after SPK transplantation, 56 patients re tained the pancreatic graft (42 of them with normofunctioning pancreas and 14 with low doses of insulin therapy). These 42 patients were selected for the autonomic study. Before transplant procedure, all CART results were abnormal. After SPK transplantation, paired test analysis showed an improvement of systolic blood pressure (SBP) response to orthostasis at the 5^th year after SPK (p = 0.03), as well as improvement of the Valsalva ratio at the 3^rd (p < 0.001) and 5^th (p = 0.001) year after SPK. After correcting for the false discovery rate, all the variables of autonomic study reached significance at different time points.

CONCLUSIONS

Prevalence of CAN in patients who are candidates for SPK transplantation is high and is generally advanced. SPK transplantation improves CAN with improved Valsalva ratio as the most precocious test.

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%.

Physical activity and dietary interventions in diabetic neuropathy: a systematic review

PURPOSE

Diabetic neuropathy is a common and disabling disorder, and there are currently no proven effective disease-modifying treatments. Physical activity and dietary interventions in patients with diabetes and diabetic neuropathy have multiple beneficial effects and are generally low risk, which makes lifestyle interventions an attractive treatment option. We reviewed the literature on the effects of physical activity and dietary interventions on length-dependent peripheral neuropathy and cardiac autonomic neuropathy in diabetes.

METHODS

The electronic database PubMed was systematically searched for original human and mouse model studies examining the effect of either dietary or physical activity interventions in subjects with diabetes, prediabetes, or metabolic syndrome.

RESULTS

Twenty studies are included in this review. Fourteen studies were human studies and six were in mice. Studies were generally small with few controlled trials, and there are no widely agreed upon outcome measures.

CONCLUSIONS

Recent research indicates that dietary interventions are effective in modifying diabetic neuropathy in animal models, and there are promising data that they may also ameliorate diabetic neuropathy in humans. It has been known for some time that lifestyle interventions can prevent the development of diabetic neuropathy in type 2 diabetes mellitus subjects. However, there is emerging evidence that lifestyle interventions are effective in individuals with established diabetic neuropathy. In addition to the observed clinical value of lifestyle interventions, there is emerging evidence of effects on biochemical pathways that improve muscle function and affect other organ systems, including the peripheral nerve. However, data from randomized controlled trials are needed.

Cardiac Autonomic Function Is Associated With Myocardial Flow Reserve in Type 1 Diabetes

The link between cardiac autonomic neuropathy and risk of cardiovascular disease is highlighted as an area in which research is needed. This study was undertaken to evaluate the association between measures of cardiac autonomic function and cardiac vascular function in type 1 diabetes using new and sensitive methods. This was a cross-sectional study in patients with type 1 diabetes, stratified by normoalbuminuria (n = 30) and macroalbuminuria (n = 30), and in healthy control subjects (n = 30). Cardiac autonomic function was evaluated using heart rate variability (HRV) indices, cardiovascular autonomic reflex tests (CARTs), and cardiac ¹²³I-metaiodobenzylguanidine (MIBG) imaging. Cardiac vascular function was assessed as myocardial flow reserve (MFR) measured by cardiac ⁸²Rb-positron emission tomography/computed tomography. The measures of cardiac autonomic function (except low frequency-to-high frequency ratio and the Valsalva test ratio) were positively correlated to MFR in unadjusted analysis. All the HRV indices lost significance after adjustment for age and heart rate. After further adjustment for relevant cardiovascular risk factors, the late heart-to-mediastinum ratio directly measuring the function of adrenergic receptors and sympathetic integrity (from the MIBG scintigraphy) and the 30-to-15 ratio (a CART), remained positively associated with MFR (P ≤ 0.04). Cardiac autonomic dysfunction, including loss of cardiac sympathetic integrity in type 1 diabetes, is associated with and may contribute to impaired myocardial blood flow regulation.

Orthostatic Hypotension in Asymptomatic Patients with Chronic Kidney Disease

Background and objective: Orthostatic hypotension (OH) is a decrease in systolic blood pressure (BP) of 20 mm Hg and in diastolic BP of 10 mm Hg when changing the position from lying to standing. Arterial hypertension (AH), comorbidities and polypharmacy contribute to its development. The aim was to assess the presence of OH and its predictors in asymptomatic chronic kidney disease (CKD) patients. Material and methods: 45 CKD patients with estimated glomerular filtration rate (eGFR) ≤ 60 mL/min/1.73 m² (CKD+) were examined for signs of OH and its predictors. The results were compared with the control group of 22 patients with eGFR > 60 mL/min/1.73 m² (CKD-). Asymptomatic patients without ischemic heart disease and previous stroke were qualified. Total blood count, serum creatinine, eGFR, urea, phosphates, calcium, albumins, parathyroid hormone, uric acid, C reactive protein, N-terminal pro b-type natriuretic peptide, lipid profile, and urine protein to creatinine ratio were assessed. Simultaneously, patients underwent echocardiography. To detect OH, a modified Schellong test was performed. Results: OH was diagnosed in 17 out of 45 CKD+ patients (average age 69.12 ± 13.2) and in 8 out of 22 CKD- patients (average age 60.50 ± 14.99). The CKD+ group demonstrated significant differences on average values of systolic and diastolic BP between OH+ and OH- patients, lower when standing. In the eGFR range of 30-60 mL/min/1.73 m² correlation was revealed between OH and β-blockers (p = 0.04), in the entire CKD+ group between β-blockers combined with diuretics (p = 0.007) and ACE-I (p = 0.033). Logistic regression test revealed that chronic heart failure (CHF, OR = 15.31), treatment with β-blockers (OR = 13.86) were significant factors influencing the presence of OH. Conclusions: Predictors of OH in CKD may include: CHF, treatment with β-blockers, combined with ACE-I and diuretics.

Association between diabetic eye disease and other complications of diabetes: Implications for care. A systematic review

The aim of this systematic review was to examine the associations between diabetic retinopathy (DR) and the common micro- and macrovascular complications of diabetes mellitus, and how these could potentially affect clinical practice. A structured search of the PubMed database identified studies of patients with diabetes that assessed the presence or development of DR in conjunction with other vascular complications of diabetes. From 70 included studies, we found that DR is consistently associated with other complications of diabetes, with the severity of DR linked to a higher risk of the presence of, or of developing, other micro- and macrovascular complications. In particular, DR increases the likelihood of having or developing nephropathy and is also a strong predictor of stroke and cardiovascular disease, and progression of DR significantly increases this risk. Proliferative DR is a strong risk factor for peripheral arterial disease, which carries a risk of lower extremity ulceration and amputation. Additionally, our findings suggest that a patient with DR has an overall worse prognosis than a patient without DR. In conclusion, this analysis highlights the need for a coordinated and collaborative approach to patient management. Given the widespread use of DR screening programmes that can be performed outside of an ophthalmology office, and the overall cost-effectiveness of DR screening, the presence and severity of DR can be a means of identifying patients at increased risk for micro- and macrovascular complications, enabling earlier detection, referral and intervention with the aim of reducing morbidity and mortality among patients with diabetes. Healthcare professionals involved in the management of diabetes should encourage regular DR screening.

An update on the diagnosis and treatment of diabetic somatic and autonomic neuropathy

Diabetic peripheral neuropathy (DPN) is the most common chronic complication of diabetes. It poses a significant challenge for clinicians as it is often diagnosed late when patients present with advanced consequences such as foot ulceration. Autonomic neuropathy (AN) is also a frequent and under-diagnosed complication unless it is overtly symptomatic. Both somatic and autonomic neuropathy are associated with increased mortality. Multiple clinical trials have failed because of limited efficacy in advanced disease, inadequate trial duration, lack of effective surrogate end-points and a lack of deterioration in the placebo arm in clinical trials of DPN. Multifactorial risk factor reduction, targeting glycaemia, blood pressure and lipids can reduce the progression of DPN and AN. Treatment of painful DPN reduces painful symptoms by about 50% at best, but there is limited efficacy with any single agent. This reflects the complex aetiology of painful DPN and argues for improved clinical phenotyping with the use of targeted therapy, taking into account co-morbid conditions such as anxiety, depression and sleep disturbance.

Update on the Impact, Diagnosis and Management of Cardiovascular Autonomic Neuropathy in Diabetes: What Is Defined, What Is New, and What Is Unmet

The burden of diabetic cardiovascular autonomic neuropathy (CAN) is expected to increase due to the diabetes epidemic and its early and widespread appearance. CAN has a definite prognostic role for mortality and cardiovascular morbidity. Putative mechanisms for this are tachycardia, QT interval prolongation, orthostatic hypotension, reverse dipping, and impaired heart rate variability, while emerging mechanisms like inflammation support the pervasiveness of autonomic dysfunction. Efforts to overcome CAN under-diagnosis are on the table: by promoting screening for symptoms and signs; by simplifying cardiovascular reflex tests; and by selecting the candidates for screening. CAN assessment allows for treatment of its manifestations, cardiovascular risk stratification, and tailoring therapeutic targets. Risk factors for CAN are mainly glycaemic control in type 1 diabetes mellitus (T1DM) and, in addition, hypertension, dyslipidaemia, and obesity in type 2 diabetes mellitus (T2DM), while preliminary data regard glycaemic variability, vitamin B12 and D changes, oxidative stress, inflammation, and genetic biomarkers. Glycaemic control prevents CAN in T1DM, whereas multifactorial intervention might be effective in T2DM. Lifestyle intervention improves autonomic function mostly in pre-diabetes. While there is no conclusive evidence for a disease-modifying therapy, treatment of CAN manifestations is available. The modulation of autonomic function by SGLT2i represents a promising research field with possible clinical relevance.

Impact of arterial hypertension and type 2 diabetes on cardiac autonomic modulation in obese individuals with recommendation for bariatric surgery

BACKGROUND AND AIM

Obese individuals with recommendation for bariatric surgery (BS) exhibit increased cardiovascular risk. The association of obesity with comorbidities, such as arterial hypertension (HTN) and type 2 diabetes mellitus (T2DM) can worsen cardiovascular dysfunction. This study aimed to investigate the effect of HTN on cardiac autonomic function and whether diabetes exacerbates HTN-related impairment of autonomic function in obese subjects.

METHODS

Samples (n=63) were allocated to three groups: Obese without HTN and T2DM (n=29), Obese with HTN (OHTN, n=17) and OHTN with T2DM (OHTN+T2DM, n=17), in which anthropometric measures, body composition, blood biochemical parameters, blood pressure (BP) and heart rate variability (HRV) were evaluated.

RESULTS

The age was higher in OHTN+T2DM and OHTN than in obese groups (p<0.05). OHTN+T2DM individuals had increased neck circumference and compromised glycemic profile when compared to obese and OHTN groups (p<0.05). Mean values for standard deviation of RR (SDRR), square root of the mean squared differences of successive RR interval (RMSSD) and number of pairs of successive normal-to-normal beat intervals that differed by 50 ms (pRR50) were significantly lower in OHTN+T2DM and OHTN groups when compared to patients with obesity alone (p<0.05). The low frequency (LF), low frequency/high frequency (LF/HF) ratio were higher in the OHTN+T2DM and OHTN than subjects with obesity alone (p<0.05). Nonlinear parameters SD2 and SD1 were also lower in the OHTN+T2DM when compared to the obese group (p<0.05). However, the SD2/SD1 ratio was higher in the OHTN+T2DM and OHTN groups than the obese group.

CONCLUSION

T2DM and/or HTN impair the cardiac autonomic function in obese patients. However, the presence of T2DM did not exacerbate the hypertension-related impairment of autonomic function.

Generalised arterial calcification in normoalbuminuric patients with type 1 diabetes with and without cardiovascular autonomic neuropathy

BACKGROUND

Type 1 diabetes is associated with increased risk of cardiovascular disease and the diabetic complication cardiovascular autonomic neuropathy in itself entails increased cardiovascular risk by mechanisms not yet fully understood. Arterial calcification is an important predictor of cardiovascular events; the aim of this study was to investigate the level of generalised arterial calcification in patients with long-term, normoalbuminuric type 1 diabetes and the association with cardiovascular autonomic neuropathy, as these factors have not been investigated in type 1 diabetes.

METHODS

Participants were examined for calcification of coronary and carotid arteries through non-contrast multi-detector computed tomography scans. Generalised arterial calcification was defined as the presence of calcium in both the coronary and carotid arteries.

RESULTS

A total of 53 patients with type 1 diabetes were included. Coronary and carotid artery calcium scores were correlated ( r = 0.720, p < 0.0001). Cardiovascular autonomic neuropathy was associated with increased coronary ( p = 0.002) and carotid ( p = 0.001) artery calcium scores. Seventeen of 20 patients with cardiovascular autonomic neuropathy (85%) demonstrated generalised arterial calcification compared to 11 (33%) patients without cardiovascular autonomic neuropathy; patients with cardiovascular autonomic neuropathy had an odds ratio of 11.3 (95% confidence interval = 2.7-47.1, p < 0.001) for generalised arterial calcification.

CONCLUSION

Cardiovascular autonomic neuropathy is associated with increased level of generalised arterial calcification in patients with normoalbuminuric, long-term type 1 diabetes.

Blood Pressure Variability and Autonomic Dysfunction

PURPOSE OF REVIEW

This review considers the relationship between abnormal blood pressure (BP) variability and autonomic dysfunction through an attempt to answer questions about its clinical relevance and pertinence to diabetes and cardiovascular autonomic neuropathy (CAN) and which therapeutic measures can lessen its cardiovascular impact.

RECENT FINDINGS

Office, ambulatory, and home BP monitoring identify posture-related, circadian, short-term, and long-term BP variabilities. Abnormal BP variability is a risk marker for organ damage, mortality, and cardiovascular events. Moreover, BP variability changes are common in diabetes and associated with CAN and possibly exacerbated by comorbidities like nephropathy, obstructive sleep apnoea syndrome, and chronic pain. The prognostic role of nondipping and reverse dipping is well documented in diabetes. Some findings suggest the possibility of restoring dipping with the dosage time of antihypertensive agents. Diabetes is a favorable scenario for altered BP variability, which might mediate the harmful effects of CAN. Preliminary data suggest the protective effect of targeting BP variability. However, further longitudinal outcome studies are needed. In the meantime, BP variability measures and practical expedients in antihypertensive treatment should be implemented in diabetes.

Update on the Management of Diabetic Neuropathy

IN BRIEF Distal symmetric polyneuropathy (DSPN) and diabetic autonomic neuropathies, particularly cardiovascular autonomic neuropathy (CAN), are prevalent diabetes complications with high morbidity, mortality, and amputation risks. The diagnosis of DSPN is principally a clinical one based on the presence of typical symptoms combined with symmetrical, distal-to-proximal stocking-glove sensory loss. CAN is an independent risk factor for cardiovascular mortality, arrhythmia, silent ischemia, major cardiovascular events, and myocardial dysfunction. Screening for CAN in high-risk patients is recommended. Symptoms of gastroparesis are nonspecific and do not correspond with its severity. Diagnosis of gastroparesis should exclude other factors well documented to affect gastric emptying such as hyperglycemia, hypoglycemia, and certain medications. There is a lack of treatment options targeting the neuropathic disease state. Managing neuropathic pain also remains a challenge. Given the high risk of addiction, abuse, psychosocial issues, and mortality, opioids are not recommended as first-, second-, or third-line agents for treating painful DSPN.

Possible early detection of coronary artery calcium progression in type 1 diabetes: A case-control study of normoalbuminuric type 1 diabetes patients and matched controls

AIMS

Coronary artery calcium (CAC) is associated with cardiovascular (CV) disease and progression of CAC is an independent predictor of mortality. Type 1 diabetes is associated with increased CV risk, especially in persons with cardiovascular autonomic neuropathy (CAN). This study aimed to examine whether short-term progression of CAC is increased in persons with type 1 diabetes compared to matched controls and if CAN increases risk of CAC progression.

METHODS

Fifty-three normoalbuminuric persons with long-term type 1 diabetes (20 with CAN) were matched in a 1:2 ratio with 106 controls without diabetes according to age, sex and baseline CAC. All were examined twice with cardiac computed tomography scans. Progression of CAC was defined as a value ≥2.5 between the square root-transformed values of follow-up and baseline CAC volume scores.

RESULTS

The participants were examined median (interquartile range) of 25 (23-27) months (type 1 diabetes) and 29 (25-33) months (controls) apart. In multivariable logistic regression, participants with type 1 diabetes had an odds ratio of 3.3 (95% CI 1.3-8.2, p = 0.01) for CAC progression. CAN did not increase progression of CAC (p = 0.64).

CONCLUSIONS

Progression of CAC was increased in well-treated, normoalbuminuric persons with type 1 diabetes compared to matched controls without diabetes, suggesting that type 1 diabetes is a risk factor for short-term progression. This finding could explain some of the increased morbidity and mortality observed in persons with type 1 diabetes, but it does not specifically explain the increased CV risk in persons with CAN.

THYROID HORMONE REPLACEMENT REDUCES THE RISK OF CARDIOVASCULAR DISEASES IN DIABETIC NEPHROPATHY PATIENTS WITH SUBCLINICAL HYPOTHYROIDISM

OBJECTIVE

Patients with diabetic nephropathy (DMN) have an increased risk of cardiovascular disease (CVD). However, strategies to reduce this risk are limited. Thyroid hormone replacement therapy (THRT) in patients with hypothyroidism has been shown to reduce several surrogate markers of CVD. Therefore, we performed a study to determine if THRT would reduce CVD risk in patients with subclinical hypothyroidism (SCH) and DMN.

METHODS

This was a retrospective, nonrandomized study of patients with type 2 diabetes, DMN, and SCH. Those with known thyroid dysfunction or taking THRT at baseline were excluded. Patients receiving THRT for at least 180 days were included in the THRT group, while the remaining patients were assigned to the non-THRT group. The primary outcome was CVD events, which included coronary syndrome, cerebrovascular events, and peripheral artery diseases.

RESULTS

Among the 257 patients, 83 (32.3%) were in the THRT group. The mean ages were 62.7 ± 12.3 and 66.8 ± 12.4 years in the THRT and non-THRT groups, respectively. The corresponding numbers of male patients were 32 (40.0%) and 94 (53.1%). During a mean follow-up of 38.0 ± 29.2 months, 98 CVD events were observed. Acute coronary syndrome and cerebrovascular event prevalence rates were lower in the THRT group than the non-THRT group, but there was no difference for peripheral artery diseases. Multivariate Cox analysis revealed that THRT was independently associated with a decreased CVD event risk.

CONCLUSION

THRT may decrease the risk of CVD in DMN patients with SCH. Randomized trials are needed to verify this finding.

ABBREVIATIONS

CV = cardiovascular DMN = diabetic nephropathy eGFR = estimated glomerular filtration rate fT4 = free thyroxine HbA1c = glycosylated hemoglobin HR = hazard ratio hs-CRP = high-sensitivity C-reactive protein LDL-C = low-density lipoprotein cholesterol SCH = subclinical hypothyroidism T2DM = type 2 diabetes THRT = thyroid hormone replacement therapy TSH = thyroid-stimulating hormone.

Relationship between diabetes mellitus and heart rate variability in community-dwelling elders

BACKGROUND AND OBJECTIVE

Diabetes mellitus is one of the most common non-communicable diseases (NCDs) and may influence the autonomic nervous system. This study aims to analyze the autonomic control, through heart rate variability (HRV), from community-dwelling elders with (DM+) and without diabetes mellitus (DM-).

MATERIALS AND METHODS

This cross-sectional study, in which 205 elders (≥ 60 years old), from the urban area of Aiquara municipality gave their written consent to participate. HRV data was collected through a Polar RS800CX monitor with a 5-min initial record at rest, followed by the command to quickly stand up.

RESULTS

The mean age was 71 years (SD, 7.32). The population was mostly made up of women 121 (59%), with low or no schooling 123 (60%), and low income 166 (81%). HRV analysis in a frequency domain showed no difference when comparing the two groups of DM+ and DM-. Henceforth in a time domain, the rMSSD showed a median value of 16.09 (interquartile range, 9.91-30.68); pNN50 median of 0.79 (interquartile range, 0.00-6.62), with a statistical significance between the group of DM+ and DM-.

CONCLUSIONS

There is a difference between the studied groups principally in what concerns the time domain, which reflects the parasympathetic activity, suggesting that elders with diabetes mellitus may have a worse parasympathetic control.

Predictors of Cardiovascular Autonomic Neuropathy Onset and Progression in a Cohort of Type 1 Diabetic Patients

AIM

The prevalence of cardiovascular autonomic neuropathy (CAN) in diabetes mellitus is well documented. However, the rate and predictors of both the development and progression of CAN have been less studied. Hereby, we assessed the rate and the major risk factors for CAN initiation and progression in a cohort of type 1 diabetic patients followed over a three-year period.

METHODS

175 type 1 diabetic patients (mean age: 50 ± 11 years; female/male: 76/99) with positive bedside screening for CAN were included and underwent 2 standardized autonomic testings using 4 standardized tests (deep breathing, Valsalva maneuver, 30/15 ratio, and changes in blood pressure during standing), separated by 3 ± 1 years. CAN staging was achieved according to the Toronto Consensus Panel on Diabetic Autonomic Neuropathy into 4 categories: absent, possible, confirmed, or severe CAN.

RESULTS

Out of the 175 patients included, 31.4% were free of CAN, 34.2% had possible CAN, 24.6% had confirmed CAN, and 9.7% exhibited severe CAN at the first assessment. Among the 103 patients with nonsevere CAN at inclusion, forty-one (39.8%) had an increase of at least one category when reassessed and 62 (60.2%) remained stable. A bivariate analysis indicated that only BMI and exposure to selective serotonin reuptake inhibitors (SSRIs) were significantly different in both groups. A multivariate analysis indicated that lower BMI (OR: 0.15, CI 95%: 0.05-0.48, p = 0.003) and SSRI exposure (OR: 4.18, CI 95%: 1.03-16.97, p = 0.04) were the sole predictors of CAN deterioration. In the 55 patients negative for CAN at the first laboratory assessment, 12 became positive at the second assessment.

CONCLUSION

No clear predictive factor for CAN onset was identified. However, once present, CAN progression was related to low BMI and SSRI exposure.

Cardiorespiratory Fitness and Cardiac Autonomic Function in Diabetes

PURPOSE OF REVIEW

This review summarizes the current knowledge on the relationship of physical activity, exercise, and cardiorespiratory fitness (CRF) with cardiovascular autonomic neuropathy (CAN) based on epidemiological, clinical, and interventional studies.

RECENT FINDINGS

The prevalence of CAN increases with age and duration of diabetes. Further risk factors for CAN comprise poor glycemic control, dyslipidemia, abdominal obesity, hypertension, and the presence of diabetic complications. CAN has been also linked to reduced CRF. We recently showed that CRF parameters (e.g., maximal oxidative capacity or oxidative capacity at the anaerobic threshold) are associated with cardiac autonomic function in patients recently diagnosed with type 1 or type 2 diabetes. Exercise interventions have shown that physical activity can increase cardiovagal activity and reduce sympathetic overactivity. In particular, long-term and regularly, but also supervised, performed endurance and high-intense and high-volume exercise improves cardiac autonomic function in patients with type 2 diabetes. By contrast, the evidence in those with type 1 diabetes and also in individuals with prediabetes or metabolic syndrome is weaker. Overall, the studies reviewed herein addressing the question whether favorably modulating the autonomic nervous system may improve CRF during exercise programs support the therapeutic concept to promote physical activity and to achieve physical fitness. However, high-quality exercise interventions, especially in type 1 diabetes and metabolic syndrome including prediabetes, are further required to better understand the relationship between physical activity, fitness, and cardiac autonomic function.

Cardiac vagal tone, a non-invasive measure of parasympathetic tone, is a clinically relevant tool in Type 1 diabetes mellitus

AIMS

To compare a novel index of parasympathetic tone, cardiac vagal tone, with established autonomic variables and to test the hypotheses that (1) cardiac vagal tone would be associated with established time and frequency domain measures of heart rate and (2) cardiac vagal tone would be lower in people with Type 1 diabetes than in a matched healthy cohort and lower still in people with established neuropathy.

METHODS

Cardiac vagal tone is a validated cardiometrically derived index of parasympathetic tone. It is measured using a standard three-lead electrocardiogram which connects, via Bluetooth, to a smartphone application. A 5-min resting recording of cardiac vagal tone was undertaken and observational comparisons were made between 42 people with Type 1 diabetes and peripheral neuropathy and 23 without peripheral neuropathy and 65 healthy people. In those with neuropathy, 24-h heart rate variability values were compared with cardiac vagal tone. Correlations between cardiac vagal tone and clinical variables were also made.

RESULTS

Cardiac vagal tone was lower in people with established neuropathy and Type 1 diabetes in comparison with healthy participants [median (interquartile range) linear vagal scale 3.4 (1.6-5.5 vs 7.0 (5.5-9.6); P < 0.0001]. Cardiac vagal tone was positively associated with time (r = 0.8, P < 0.0001) and frequency domain markers of heart rate variability (r = 0.75, P < 0.0001), representing established measures of parasympathetic function. Cardiac vagal tone was negatively associated with age (r=-0.32, P = 0.003), disease duration (r=-0.43, P < 0.0001) and cardiovascular risk score (r=-0.32, P = 0.006).

CONCLUSIONS

Cardiac vagal tone represents a convenient, clinically relevant method of assessing parasympathetic nervous system tone, potentially facilitating the earlier identification of people with Type 1 diabetes who should undergo formal autonomic function testing.

The Quest for more Research on Painful Diabetic Neuropathy

A 62-year-old diabetologist diagnosed himself to have diabetes type-2, with an HbA1c of 9.5. Five months after lifestyle intervention and a multi-drug approach, HbA1c was 6.3, systolic blood pressure was below 135mmHg and BMI reduced to 27. But he suffered from severe painful diabetic neuropathy. Therefore he decided to visit his friend, a famous neuroscientist at an even more famous university. He asked him several plain questions: 1. What is the natural course of painful diabetic neuropathy? 2. Why do I have, despite almost normalizing HbA1c, more problems than before? 3. Are you sure my problems are due to diabetes or should we do a nerve biopsy? 4. Are there imaging techniques helpful for the diagnosis of this diabetic complication, starting in the distal nerve endings of the foot and slowly moving ahead? 5. Can you suggest any drug, specific and effective, for relieving painful diabetic neuropathy? This review will use the experts' answers to the questions of the diabetologist, not only to give a summary of the current knowledge, but even more to highlight areas of research needed for improving the fate of patients with painful diabetic neuropathy. Based on the unknowns, which exceed the knowns in diabetic neuropathy, a quest for more public support of research is made.