Diabetes and cardiac autonomic neuropathy: Clinical manifestations, cardiovascular consequences, diagnosis and treatment

The emotion paradox in the aging body and brain

With age, parasympathetic activity decreases, while sympathetic activity increases. Thus, the typical older adult has low heart rate variability (HRV) and high noradrenaline levels. Younger adults with this physiological profile tend to be unhappy and stressed. Yet, with age, emotional experience tends to improve. Why does older adults' emotional well-being not suffer as their HRV decreases? To address this apparent paradox, I present the autonomic compensation model. In this model, failing organs, the initial phases of Alzheimer's pathology, and other age-related diseases trigger noradrenergic hyperactivity. To compensate, older brains increase autonomic regulatory activity in the pregenual prefrontal cortex (PFC). Age-related declines in nerve conduction reduce the ability of the pregenual PFC to reduce hyperactive noradrenergic activity and increase peripheral HRV. But these pregenual PFC autonomic compensation efforts have a significant impact in the brain, where they bias processing in favor of stimuli that tend to increase parasympathetic activity (e.g., stimuli that increase feelings of safety) and against stimuli that tend to increase sympathetic activity (e.g., threatening stimuli). In summary, the autonomic compensation model posits that age-related chronic sympathetic/noradrenergic hyperactivity stimulates regulatory attempts that have the side effect of enhancing emotional well-being.

Perioperative changes of serum orphanin in diabetic patients and its relationship with sympathetic nervous system

The occurrence of cardiovascular events in diabetic patients during the perioperative period is related to the activation of sympathetic nerves. Basic research shows that serum nociceptin/orphanin FQ (N/OFQ) levels in diabetic neuropathy rats increased, and N/OFQ reduces the release of norepinephrine (NE). We hypothesize that N/OFQ will affect the sympathetic nervous system during perioperative myocardium of diabetic patients. 66 patients with unilateral knee arthroplasty were divided into diabetes group (D group) and non-diabetes group (N group). Measured blood glucose, serum NE, N/OFQ concentrations at the 30 min before anesthesia (T0), 1 h after surgery (T1), 24 h after surgery (T2) and the cardiac troponinI (cTnI) concentration at T0 and T2. Compared with N group, the concentration of blood glucose, N/OFQ and cTnI in D group was higher and the NE was lower at T0 (P < 0.05). At T1, the blood glucose, N/OFQ, NE concentrations of D group increased, only the blood glucose increased in N group (P < 0.05). Serum N/OFQ of D group from T0 to T1 was correlated with the change trend of blood glucose, NE concentration from T0 to T1 and cTnI from T0 to T2(r = 0.386, P = 0.027; r = 0.350, P = 0.046; r = 0.363, P = 0.038). The outcomes demonstrated that the preoperative serum N/OFQ concentration in diabetic patients was increased, and the increase in N/OFQ concentration during the operation was related to the increase in NE and cTnI concentrations, perioperative N/OFQ may mediate myocardial injury through sympathetic nervous system.

Harnessing the Synergy of SGLT2 Inhibitors and Continuous Ketone Monitoring (CKM) in Managing Heart Failure among Patients with Type 1 Diabetes

Heart failure (HF) management in type 1 diabetes (T1D) is particularly challenging due to its increased prevalence and the associated risks of hospitalization and mortality, driven by diabetic cardiomyopathy. Sodium-glucose cotransporter-2 inhibitors (SGLT2-is) offer a promising avenue for treating HF, specifically the preserved ejection fraction variant most common in T1D, but their utility is hampered by the risk of euglycemic diabetic ketoacidosis (DKA). This review investigates the potential of SGLT2-is in T1D HF management alongside emergent Continuous Ketone Monitoring (CKM) technology as a means to mitigate DKA risk through a comprehensive analysis of clinical trials, observational studies, and reviews. The evidence suggests that SGLT2-is significantly reduce HF hospitalization and enhance cardiovascular outcomes. However, their application in T1D patients remains limited due to DKA concerns. CKM technology emerges as a crucial tool in this context, offering real-time monitoring of ketone levels, which enables the safe incorporation of SGLT2-is into treatment regimes by allowing for early detection and intervention in the development of ketosis. The synergy between SGLT2-is and CKM has the potential to revolutionize HF treatment in T1D, promising improved patient safety, quality of life, and reduced HF-related morbidity and mortality. Future research should aim to employ clinical trials directly assessing this integrated approach, potentially guiding new management protocols for HF in T1D.

The State of Cardiac Rehabilitation in Saudi Arabia: Barriers, Facilitators, and Policy Implications

Cardiovascular disease (CVD) is a critical public health issue in Saudi Arabia, where it is the leading cause of death. The economic burden of CVD in the country is expected to triple by 2035, reaching $9.8 billion. This paper provides an overview of CVD in Saudi Arabia and its risk factors, impact on healthcare, and effects on patients' quality of life. The review emphasizes the potential of cardiac rehabilitation (CR) programs in addressing the CVD epidemic. CR programs have been shown to reduce morbidity, mortality, and hospital readmissions while improving patients' cardiovascular health and overall well-being. However, these programs are underutilized and inaccessible in Saudi Arabia. The paper highlights the urgent need for CR programs in the country and suggests key strategies for implementation. These include increasing patient referrals, tailoring programs to individual needs, enhancing patient education, and making CR accessible through home-based options. Fostering multidisciplinary collaboration and developing tailored guidelines for Arab countries can further enhance the impact of CR programs. In conclusion, this review underscores the vital importance of comprehensive CR programs in Saudi Arabia to combat the rising CVD burden, improve patient quality of life, and align with the goals of the Saudi 2030 Vision for a healthier society.

Dermatoses in overweight and obese children and their relationship with insulin and skin color

BACKGROUND/AIM

The aim of the present study was to investigate the prevalence of obesity-related dermatoses in obese children, and the association between these dermatoses and insulin resistance as well as skin color.

METHODS

Obese, overweight, and normal weight children according to body mass index who were followed up and treated in the outpatient clinics were included in the study. Dermatological examinations of the participants were performed, and fasting insulin and glucose levels were checked.

RESULTS

The obese and overweight children were evaluated as the patient group (70 girls, 41 boys, mean age: 12.37 ± 3.14 years). One hundred one healthy children with normal weight were determined as the control group (59 girls, 42 boys, mean age: 12.15 ± 2.43). The first five common dermatoses in the patient group when compared with the control group were keratosis pilaris (KP), striae distensae, hyperhidrosis, acanthosis nigricans (AN), and plantar hyperkeratosis. The first five dermatoses which were positively correlated with formation and insulin resistance were KP, striae distensae, AN, hyperhidrosis, and plantar hyperkeratosis. According to the Fitzpatrick skin scale, we found that the darker the skin color, the higher the probability of AN and KP (OR, 0.298; 95% CI, 0.106-0.834, p = 0.021; OR, 0.306; 95% CI, 0.117-0.796, p = 0.015, respectively).

CONCLUSION

Some dermatoses associated with obesity and insulin resistance were not found in obese children, or there was no significant association. These results indicate that many skin morbidities may be prevented by preventing and treating obesity and insulin resistance in the early period.

Evaluating treatment options for cardiovascular autonomic neuropathy in patients with diabetes mellitus: a systematic review

Background

Cardiovascular autonomic neuropathy (CAN) is a debilitating complication of diabetes mellitus. To date, there is no systematic review on all the available drug treatments for CAN in diabetic patients, except for one review focusing on aldose reductase inhibitors.

Objective

To evaluate available drug treatment options for CAN in diabetic patients.

Methods

A systematic review was conducted with a search of CENTRAL, Embase, PubMed and Scopus from database inception till 14th May 2022. Randomised controlled trials (RCTs) of diabetic patients with CAN that investigated the effect of treatment on blood pressure, heart rate variability, heart rate or QT interval were included.

Results

Thirteen RCTs with a total of 724 diabetic patients with CAN were selected. There was a significant improvement in the autonomic indices of diabetic patients with CAN given angiotensin-converting enzyme inhibitor (ACEI) for 24 weeks (p<0.05) to two years (p<0.001), angiotensin-receptor blocker (ARB) for one year (p<0.05), single dose of beta blocker (BB) (p<0.05), omega-3 polyunsaturated fatty acids (PUFAs) for three months (p<0.05), alpha-lipoic acid (ALA) for four months (p < 0.05) to six months (p=0.048), vitamin B12 in combination with ALA, acetyl L‑carnitine (ALC), superoxide dismutase (SOD) for one year (p=0.001)  and near significant improvement in the autonomic indices of diabetic patients with CAN given vitamin E for four months (p = 0.05) compared to the control group. However, there was no significant improvement in the autonomic indices of patients given vitamin B12 monotherapy (p ≥ 0.05).

Conclusion

ACEI, ARB, BB, ALA, omega-3 PUFAs, vitamin E, vitamin B12 in combination with ALA, ALC and SOD could be effective treatment options for CAN, while vitamin B12 monotherapy might be unlikely to be recommended for the treatment of CAN due to its lack of efficacy.

Supplementary Information

The online version contains supplementary material available at 10.1007/s13340-023-00629-x.

Parasympathetic autonomic dysfunction is more often evidenced than sympathetic autonomic dysfunction in fluctuating and polymorphic symptoms of "long-COVID" patients

Several disabling symptoms potentially related to dysautonomia have been reported in "long-COVID" patients. Unfortunately, these symptoms are often nonspecific, and autonomic nervous system explorations are rarely performed in these patients. This study aimed to evaluate prospectively a cohort of long-COVID patients presenting severe disabling and non-relapsing symptoms of potential dysautonomia and to identify sensitive tests. Autonomic function was assessed by clinical examination, the Schirmer test; sudomotor evaluation, orthostatic blood pressure (BP) variation, 24-h ambulatory BP monitoring for sympathetic evaluation, and heart rate variation during orthostatism, deep breathing and Valsalva maneuvers for parasympathetic evaluation. Test results were considered abnormal if they reached the lower thresholds defined in publications and in our department. We also compared mean values for autonomic function tests between patients and age-matched controls. Sixteen patients (median age 37 years [31-43 years], 15 women) were included in this study and referred 14.5 months (median) [12.0-16.5 months] after initial infection. Nine had at least one positive SARS-CoV-2 RT-PCR or serology result. Symptoms after SARS-CoV-2 infection were severe, fluctuating and disabling with effort intolerance. Six patients (37.5%) had one or several abnormal test results, affecting the parasympathetic cardiac function in five of them (31%). Mean Valsalva score was significantly lower in patients than in controls. In this cohort of severely disabled long-COVID patients, 37.5% of them had at least one abnormal test result showing a possible contribution of dysautonomia to these nonspecific symptoms. Interestingly, mean values of the Valsalva test were significantly lower in patients than in control subjects, suggesting that normal values thresholds might not be appropriate in this population.

Cardiovascular autonomic neuropathy is associated with increased glycemic variability driven by hyperglycemia rather than hypoglycemia in patients with diabetes

AIM

Cardiac autonomic neuropathy (CAN) has been suggested to be associated with hypoglycemia and impaired hypoglycemia unawareness. We have assessed the relationship between CAN and extensive measures of glucose variability (GV) in patients with type 1 and type 2 diabetes.

METHODS

Participants with diabetes underwent continuous glucose monitoring (CGM) to obtain measures of GV and the extent of hyperglycemia and hypoglycemia and cardiovascular autonomic reflex testing.

RESULTS

Of the 40 participants (20 T1DM and 20 T2DM) (aged 40.70±13.73 years, diabetes duration 14.43±7.35 years, HbA1c 8.85±1.70%), 23 (57.5%) had CAN. Despite a lower coefficient of variation (CV) (31.26±11.87 vs. 40.33±11.03, P=0.018), they had a higher CONGA (8.42±2.58 vs. 6.68±1.88, P=0.024) with a lower median LBGI (1.60 (range: 0.20-3.50) vs. 4.90 (range: 3.20-7.40), P=0.010) and percentage median time spent in hypoglycemia (4 (range:4-13) vs. 1 (range:0-5), P=0.008), compared to those without CAN. The percentage GRADE_Euglycemia (3.30±2.78 vs. 5.69±3.09, P=0.017) and GRADE_Hypoglycemia (0.3 (range: 0 - 3.80) vs. 1.8 (range: 0.9-6.5), P=0.036) were significantly lower, while the percentage median GRADE_{Hyperglycemia} (95.45 (range:93-98) vs. 91.6 (82.8-95.1), P=0.013) was significantly higher in participants with CAN compared to those without CAN.

CONCLUSION

CAN was associated with increased glycemic variability with less time in euglycemia attributed to a greater time in hyperglycemia but not hypoglycemia.

Blood Pressure Variability in Clinical Practice: Past, Present and the Future

Recent advances in wearable technology through convenient and cuffless systems will enable continuous, noninvasive monitoring of blood pressure (BP), heart rate, and heart rhythm on both longitudinal 24-hour measurement scales and high-frequency beat-to-beat BP variability and synchronous heart rate variability and changes in underlying heart rhythm. Clinically, BP variability is classified into 4 main types on the basis of the duration of monitoring time: very-short-term (beat to beat), short-term (within 24 hours), medium-term (within days), and long-term (over months and years). BP variability is a strong risk factor for cardiovascular diseases, chronic kidney disease, cognitive decline, and mental illness. The diagnostic and therapeutic value of measuring and controlling BP variability may offer critical targets in addition to lowering mean BP in hypertensive populations.

Assessment of Hydration, Nutritional Status and Arterial Stiffness in Hypertensive Chronic Kidney Disease Patients

The aim of this cross-sectional study was to determine the body fluid volume in patients diagnosed with both chronic kidney disease (CKD) and arterial hypertension (AH), and to investigate the relationship between fluid overload (FO), nutritional status and arterial stiffness in this specific patient population. A total of 169 participants with CKD and AH were enrolled in the study, and data on general parameters, comorbidities, medication use, and laboratory parameters were collected. Body composition was assessed with a Tanita MC 780 device, and data on the central and peripheral systolic and diastolic blood pressure, as well as pulse wave velocity (PWV) and the augmentation index (AIx) were collected with an IEM Mobil-O-Graph 24 h ambulatory blood pressure monitor, which was based on oscillometry. The Mediterranean Diet Serving Score (MDSS) questionnaire was used to determine the adherence to the Mediterranean diet (MeDi). Our results showed that the significant positive predictors of hydration status were the use of diuretics and oral hypoglycemic agents, whereas the negative predictors were female sex, higher body mass index level and use of two or more antihypertensives in the form of a single-pill combination. We also found differences in blood pressure and arterial stiffness parameters in relation to volume status, along with differences based on the presence of diabetes mellitus (DM). In conclusion, these results call for a higher awareness of volume status in the care of CKD patients with AH, especially in those with diabetes mellitus.

The Role of Heart Rate Variability (HRV) in Different Hypertensive Syndromes

Cardiac innervation by the parasympathetic nervous system (PNS) and the sympathetic nervous system (SNS) modulates the heart rate (HR) (chronotropic activity) and the contraction of the cardiac muscle (inotropic activity). The peripheral vasculature is controlled only by the SNS, which is responsible for peripheral vascular resistance. This also mediates the baroreceptor reflex (BR), which in turn mediates blood pressure (BP). Hypertension (HTN) and the autonomic nervous system (ANS) are closely related, such that derangements can lead to vasomotor impairments and several comorbidities, including obesity, hypertension, resistant hypertension, and chronic kidney disease. Autonomic dysfunction is also associated with functional and structural changes in target organs (heart, brain, kidneys, and blood vessels), increasing cardiovascular risk. Heart rate variability (HRV) is a method of assessing cardiac autonomic modulation. This tool has been used for clinical evaluation and to address the effect of therapeutic interventions. The present review aims (a) to approach the heart rate (HR) as a CV risk factor in hypertensive patients; (b) to analyze the heart rate variability (HRV) as a "tool" to estimate the individual risk stratum for Pre-HTN (P-HTN), Controlled-HTN (C-HTN), Resistant and Refractory HTN (R-HTN and Rf-HTN, respectively), and hypertensive patients with chronic renal disease (HTN+CKD).

A Review on Autonomic Functional Assessment in Diabetic Patients

In today's world, science has progressed significantly, yet most people are still unaware of diabetes. Lack of obesity, physical work, and lifestyle changes are the main factors. Diabetes is becoming more common all around the globe. Type 2 diabetes may go unnoticed for years, resulting in serious consequences and high healthcare expenses. The goal of this study is to look at a wide range of studies in which the autonomic function of diabetic people has been studied with the help of various autonomic function tests (AFTs). AFT is a non-invasive approach to assessing patients for testing sympathetic and parasympathetic responses to stimuli. AFT findings give us comprehensive knowledge of the autonomic physiology reactions in normal and in autonomic diseases like diabetes. This review will concentrate on AFTs that are scientifically valid, trustworthy, and clinically beneficial, according to experts.

Heart rate variability in different sleep stages is associated with metabolic function and glycemic control in type 2 diabetes mellitus

Introduction: Autonomic nervous system (ANS) plays an important role in the exchange of metabolic information between organs and regulation on peripheral metabolism with obvious circadian rhythm in a healthy state. Sleep, a vital brain phenomenon, significantly affects both ANS and metabolic function. Objectives: This study investigated the relationships among sleep, ANS and metabolic function in type 2 diabetes mellitus (T2DM), to support the evaluation of ANS function through heart rate variability (HRV) metrics, and the determination of the correlated underlying autonomic pathways, and help optimize the early prevention, post-diagnosis and management of T2DM and its complications. Materials and methods: A total of 64 volunteered inpatients with T2DM took part in this study. 24-h electrocardiogram (ECG), clinical indicators of metabolic function, sleep quality and sleep staging results of T2DM patients were monitored. Results: The associations between sleep quality, 24-h/awake/sleep/sleep staging HRV and clinical indicators of metabolic function were analyzed. Significant correlations were found between sleep quality and metabolic function (|r| = 0.386 ± 0.062, p < 0.05); HRV derived ANS function showed strengthened correlations with metabolic function during sleep period (|r| = 0.474 ± 0.100, p < 0.05); HRV metrics during sleep stages coupled more tightly with clinical indicators of metabolic function [in unstable sleep: |r| = 0.453 ± 0.095, p < 0.05; in stable sleep: |r| = 0.463 ± 0.100, p < 0.05; in rapid eye movement (REM) sleep: |r| = 0.453 ± 0.082, p < 0.05], and showed significant associations with glycemic control in non-linear analysis [fasting blood glucose within 24 h of admission (admission FBG), |r| = 0.420 ± 0.064, p < 0.05; glycated hemoglobin (HbA1c), |r| = 0.417 ± 0.016, p < 0.05]. Conclusions: HRV metrics during sleep period play more distinct role than during awake period in investigating ANS dysfunction and metabolism in T2DM patients, and sleep rhythm based HRV analysis should perform better in ANS and metabolic function assessment, especially for glycemic control in non-linear analysis among T2DM patients.

Ferroptosis increases obesity: Crosstalk between adipocytes and the neuroimmune system

Ferroptosis requires not only the accumulation of iron ions, but also changes in many ferroptosis-related regulators, including a decrease in GPX4 and inhibition of SLC7A11 for classical ferroptosis, a deletion of FSP1 or GCH1. Surprisingly, adipose tissue (AT) in the obesity conditions is also accompanied by iron buildup, decreased GSH, and increased ROS. On the neurological side, the pro-inflammatory factor released by AT may have first caused ferroptosis in the vagus nerve by inhibiting of the NRF2-GPX4 pathway, resulting in disorders of the autonomic nervous system. On the immune side, obesity may cause M2 macrophages ferroptosis due to damage to iron-rich ATMs (MFe^hi) and antioxidant ATMs (Mox), and lead to Treg cells ferroptosis through reductions in NRF2, GPX4, and GCH1 levels. At the same time, the reduction in GPX4 may also trigger the ferroptosis of B1 cells. In addition, some studies have also found the role of GPX4 in neutrophil autophagy, which is also worth pondering whether there is a connection with ferroptosis. In conclusion, this review summarizes the associations between neuroimmune regulation associated with obesity and ferroptosis, and on the basis of this, highlights their potential molecular mechanisms, proposing that ferroptosis in one or more cells in a multicellular tissue changes the fate of that tissue.

Cardiac autonomic dysfunctions in type 2 diabetes mellitus: an investigative study with heart rate variability measures

Cardiac autonomic neuropathy (CAN) is a common yet underdiagnosed complication of Type 2 diabetes mellitus (T2DM). Heart rate variability (HRV), a sensitive diagnostic marker of cardiovascular risk, could help detect CAN at its earliest stage. However, the progression of CAN based on age and disease duration in T2DM is lacking. In this study, we propose to explore the occurrence of CAN in patients with varying stages and duration of T2DM. This cross-sectional study involves participants with T2DM (n = 160) and healthy volunteers (n = 40) with an age range of 30-60 years of both genders. Patients in the T2DM group were further subdivided into four subgroups based on their disease duration [Prediabetes, disease duration <5 yrs (D1), 5-10 yrs (D2), and >10 yrs (D3)]. All participants underwent short-term HRV recording for 20 minutes and analyzed for both time and frequency domain measures. The study results showed a significant increase in Heart Rate (HR) in D1 (P = 0.031) and D3 (P = 0.001) groups compared to healthy controls. The time-domain measures of HRV were significantly reduced in the T2DM group compared to the healthy controls. Furthermore, this reduction is more intense in the D3 group than in D2 and D1. Correspondingly, in frequency domain parameters: total power, high-frequency power, and low-frequency power were significantly reduced in all the T2DM groups compared to healthy controls. The study concludes that the overall HRV (as determined by total power), sympathetic activity (low frequency power) and parasympathetic activity (time domain measures and high frequency power) were significantly reduced in all the diabetic subgroups except prediabetes as compared to the healthy controls, implying that both sympathetic and parasympathetic limbs are symmetrically affected in T2DM patients even in the earliest stages (<5 yrs) implying subclinical cardiac autonomic dysfunction in the earliest stages.

Diabesity in Elderly Cardiovascular Disease Patients: Mechanisms and Regulators

Cardiovascular disease (CVD) is the leading cause of death in the world. In 2019, 550 million people were suffering from CVD and 18 million of them died as a result. Most of them had associated risk factors such as high fasting glucose, which caused 134 million deaths, and obesity, which accounted for 5.02 million deaths. Diabesity, a combination of type 2 diabetes and obesity, contributes to cardiac, metabolic, inflammation and neurohumoral changes that determine cardiac dysfunction (diabesity-related cardiomyopathy). Epicardial adipose tissue (EAT) is distributed around the myocardium, promoting myocardial inflammation and fibrosis, and is associated with an increased risk of heart failure, particularly with preserved systolic function, atrial fibrillation and coronary atherosclerosis. In fact, several hypoglycaemic drugs have demonstrated a volume reduction of EAT and effects on its metabolic and inflammation profile. However, it is necessary to improve knowledge of the diabesity pathophysiologic mechanisms involved in the development and progression of cardiovascular diseases for comprehensive patient management including drugs to optimize glucometabolic control. This review presents the mechanisms of diabesity associated with cardiovascular disease and their therapeutic implications.

Triglyceride glucose index is related with cardiac autonomic dysfunction in patients with metabolic syndrome

Aim    Cardiac autonomic dysfunction is encountered in approximately 25 % of patients with metabolic syndrome (MetS). 24 hr Holter-ECG based heart rate variability (HRV) and heart rate turbulence (HRT) parameters are used to evaluate cardiac autonomic function. We aimed to investigate the relationship between a novel insulin resistance marker, triglyceride glucose (TyG) index and cardiac autonomic dysfunction in patients with MetS.Material and methods    We examined a total of 400 non-diabetic subjects, 136 with MetS and 264 without MetS. All underwent TyG index calculations, and 24 hr Holter-ECG recordings for the measurement of HRV and HRT parameters.Results    HRV and HRT parameters were lower or higher in patients with MetS than in subjects without MetS, indicating cardiac autonomic dysfunction. We observed significant correlations between TyG index and measures of cardiac autonomic function. Multiple linear regression analysis showed that the TyG index was an independent predictor of almost all HRV and HRT parameters.Conclusion    This study demonstrates the independent relationship between cardiac autonomic dysfunction and the TyG index, a novel marker of insulin resistance in non-diabetic patients with MetS.

Fluoxetine Treatment Decreases Cardiac Vagal Input and Alters the Serotonergic Modulation of the Parasympathetic Outflow in Diabetic Rats

Comorbid diabetes and depression constitutes a major health problem, worsening associated cardiovascular diseases. Fluoxetine's (antidepressant) role on cardiac diabetic complications remains unknown. We determined whether fluoxetine modifies cardiac vagal input and its serotonergic modulation in male Wistar diabetic rats. Diabetes was induced by alloxan and maintained for 28 days. Fluoxetine was administered the last 14 days (10 mg/kg/day; p.o). Bradycardia was obtained by vagal stimulation (3, 6 and 9 Hz) or i.v. acetylcholine administrations (1, 5 and 10 μg/kg). Fluoxetine treatment diminished vagally-induced bradycardia. Administration of 5-HT originated a dual action on the bradycardia, augmenting it at low doses and diminishing it at high doses, reproduced by 5-CT (5-HT_1/7 agonist). 5-CT did not alter the bradycardia induced by exogenous acetylcholine. Decrease of the vagally-induced bradycardia evoked by high doses of 5-HT and 5-CT was reproduced by L-694,247 (5-HT_1D agonist) and blocked by prior administration of LY310762 (5-HT_1D antagonist). Enhancement of the electrical-induced bradycardia by 5-CT (10 μg/kg) was abolished by pretreatment with SB269970 (5-HT₇ receptor antagonist). Thus, oral fluoxetine treatment originates a decrease in cardiac cholinergic activity and changes 5-HT modulation of bradycardic responses in diabetes: prejunctional 5-HT₇ receptors augment cholinergic-evoked bradycardic responses, whereas prejunctional 5-HT_1D receptors inhibit vagally-induced bradycardia.

Naringin Relieves Diabetic Cardiac Autonomic Neuropathy Mediated by P2Y14 Receptor in Superior Cervical Ganglion

Diabetes mellitus (DM), an emerging chronic epidemic, contributes to mortality and morbidity around the world. Diabetic cardiac autonomic neuropathy (DCAN) is one of the most common complications associated with DM. Previous studies have shown that satellite glial cells (SGCs) in the superior cervical ganglia (SCG) play an indispensable role in DCAN progression. In addition, it has been shown that purinergic neurotransmitters, as well as metabotropic GPCRs, are involved in the pathophysiological process of DCAN. Furthermore, one traditional Chinese medicine, naringin may potently alleviate the effects of DCAN. Ferroptosis may be involved in DCAN progression. However, the role of naringin in DCAN as well as its detailed mechanism requires further investigation. In this research, we attempted to identify the effect and relevant mechanism of naringin in DCAN mitigation. We observed that compared with those of normal subjects, there were significantly elevated expression levels of P2Y₁₄ and IL-1β in diabetic rats, both of which were remarkably diminished by treatment with either P2Y₁₄ shRNA or naringin. In addition, abnormalities in blood pressure (BP), heart rate (HR), heart rate variability (HRV), sympathetic nerve discharge (SND), and cardiac structure in the diabetic model can also be partially returned to normal through the use of those treatments. Furthermore, a reduced expression of NRF2 and GPX4, as well as an elevated level of ROS, were detected in diabetic cases, which can also be improved with those treatments. Our results showed that naringin can effectively relieve DCAN mediated by the P2Y₁₄ receptor of SGCs in the SCG. Moreover, the NRF2/GPX4 pathway involved in ferroptosis may become one of the principal mechanisms participating in DCAN progression, which can be modulated by P2Y₁₄-targeted naringin and thus relieve DCAN. Hopefully, our research can supply one novel therapeutic target and provide a brilliant perspective for the treatment of DCAN.

Glycemic status, non-traditional risk and left ventricular structure and function in the Jackson Heart Study

BACKGROUND

Left ventricular structure and function abnormalities may be an early marker of cardiomyopathy among African Americans with diabetes (DM) even in the absence of coronary artery disease (CAD), arrhythmia, valvular heart disease and end-stage renal disease (ESRD). This study examined the association of prediabetes (PDM), DM and HbA1c with left ventricular structure and function among Jackson Heart Study (JHS) participants without traditional risk factors.

METHODS

Retrospective cross-sectional analyses of the association of PDM, DM and HbA1c with, left ventricular ejection fraction (LV EF), fractional shortening (LV FS), stroke volume index (SVI), cardiac index (CI), left ventricular end diastolic volume index (LVEDVI), left ventricular end systolic volume index (LVESVI), relative wall thickness (RWT), myocardial contraction fraction (MCF) and left ventricular mass index (LVMI). The study was conducted in 2234 adult JHS participants without preexisting CAD, arrhythmia, valvular heart disease or ESRD. Statistical analyses included descriptive, univariate and covariate adjusted linear regression analyses. Sensitivity analyses to explore the impact of hypertension on study outcomes were also carried out.

RESULTS

DM compared with no DM was associated with lower, SVI (- 0.96 ml/m², p = 0.029), LVEDVI (- 1.44 ml/m² p = 0.015), and MCF (- 1.90% p = 0.007) but higher CI (0.14 L/min/m², p < 0.001), RWT (0.01 cm, p = 0.002) and LVMI (2.29 g/m², p = 0.009). After further control for DM duration, only CI remaining significantly higher for DM compared with no DM participants (0.12 L/min/m², p = 0.009). PDM compared with no PDM was associated with lower, SVI (- 0.87 ml/m², P = 0.024), LVEDVI (- 1.15 ml/m² p = 0.003) and LVESVI (- 0.62 ml/m² p = 0.025). HbA1c ≥ 8.0% compared with HbA1c < 5.7% was associated with lower SVI (- 2.09 ml/m², p = 0.004), LVEDVI (- 2.11 ml/m² p = 0.032) and MCF (- 2.94% p = 0.011) but higher CI (0.11 L/min/m², p = 0.043) and RWT (0.01 cm, p = 0.035).

CONCLUSIONS

Glycemic status is associated with important left ventricular structure and function changes among African Americans without prior CAD, arrhythmia, valvular heart disease and ESRD. Longitudinal studies may further elucidate these relationships.

Novel Application of Multiscale Cross-Approximate Entropy for Assessing Early Changes in the Complexity between Systolic Blood Pressure and ECG R-R Intervals in Diabetic Rats

Cardiac autonomic neuropathy (CAN) is a common complication of diabetes mellitus, and can be assessed using heart rate variability (HRV) and the correlations between systolic blood pressure (SBP) and ECG R-R intervals (RRIs), namely baroreflex sensitivity (BRS). In this study, we propose a novel parameter for the nonlinear association between SBP and RRIs based on multiscale cross-approximate entropy (MS-CXApEn). Sixteen male adult Wistar Kyoto rats were equally divided into two groups: streptozotocin-induced diabetes and age-matched controls. RRIs and SBP were acquired in control rats and the diabetic rats at the onset of hyperglycemia and insulin-treated euglycemia to determine HRV by the ratio of low-frequency to high-frequency power (LF/HF) and Poincaré plot as SSR (SD1/SD2), BRS, and MS-CXApEn. SSR and BRS were not significantly different among the three groups. The LF/HF was significantly higher in the hyperglycemic diabetics than those in the controls and euglycemic diabetic rats. MS-CXApEn was higher in the diabetic hyperglycemic rats than the control rats from scales 2 to 10, and approached the values of controls in diabetic euglycemic rats at scales 9 and 10. Conclusions: We propose MS-CXApEn as a novel parameter to quantify the dynamic nonlinear interactions between SBP and RRIs that reveals more apparent changes in early diabetic rats. Furthermore, changes in this parameter were related to correction of hyperglycemia and could be useful for detecting and assessing CAN in early diabetes.

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.

Association Between Serum Albumin Levels and Diabetic Peripheral Neuropathy Among Patients with Type 2 Diabetes: Effect Modification of Body Mass Index

BACKGROUND

The role of serum albumin in the risk of diabetic peripheral neuropathy (DPN) remains unclear. This study aimed to explore the relationship between serum albumin level and DPN, and to examine any possible effect modifiers among patients with type 2 diabetes mellitus.

METHODS

This cross-sectional study was conducted in Jiangxi, China, from May 2012 to December 2014. Serum albumin levels were determined in 523 subjects, and the association between serum albumin level and DPN was evaluated using linear regression models (odds ratio [OR] and corresponding 95% confidence interval [CI]).

RESULTS

There was a significant inverse association between serum albumin level (per 1 g/L increment, OR 0.95 [95% CI 0.92-0.98]) and the risk of DPN. Accordingly, when serum albumin was assessed as quartiles, a significantly lower risk of DPN was found in participants in quartile 4 (OR 0.49 [95% CI 0.25-0.95]), compared with those in quartile 1. Consistently, higher albumin levels (≥35 g/L) were associated with decreased odds for DPN (OR 0.36 [95% CI 0.17-0.74]) compared with lower levels. Furthermore, the albumin-DPN association was significantly stronger in patients with a relatively high body mass index (BMI; ≥24 kg/m²; OR 0.91 [95% CI 0.85-0.98]) than in those with a low BMI (<24 kg/m²; OR 0.99 [95% CI 0.94-1.04]; P for interaction = 0.042).

CONCLUSION

These data suggest that serum albumin level could be a novel risk factor for DPN among patients with type 2 diabetes and relatively high BMI (>24 kg/m²).

Effect of alpha-lipoic acid on arterial stiffness parameters in type 2 diabetes mellitus patients with cardiac autonomic neuropathy

Objective. Significantly underdiagnosed, diabetes-associated cardiac autonomic neuropathy (CAN) causes a wide range of cardiac disorders that may cause life-threatening outcomes. This study investigated the effects of alpha-lipoic acid (ALA) on arterial stiffness and insulin resistance (IR) parameters in type 2 diabetes mellitus (T2D) patients and definite CAN. Methods. A total of 36 patients with T2D and a definite stage of CAN were recruited. This investigation was carried out on two separate arms: traditional hypoglycemic therapy (n=18, control) and ALA (n=18) 600 mg in film-coated tablets/q.d. in addition to traditional hypoglycemic therapy. The duration of the study was three months. Results. In subjects with T2D and definite stage of СAN, treatment with ALA resulted in a significant decrease of glucose, immunoreactive insulin concentration, and Homeostasis Model Assessment (HOMA)-IR (HOMA-IR) parameters; pulse wave velocity (PWV), aorta augmentation index (AIxao) during the active period of the day and decrease of PWV, AIxao, and brachial augmentation index during the passive period of the day compared with the results, obtained in the control group. Therefore, the administration of ALA to patients with T2D for three months promotes the improvement of glucose metabolism and arterial stiffness parameters. Conclusions. In patients with T2D and definite stage of СAN treatment with ALA improved HOMA-IR and arterial stiffness parameters. These findings can be of clinical significance for the complex treatment of diabetes-associated CAN.

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.

Autonomic and Somatic Nerve Functions in Type 2 Diabetes Mellitus Patients: Electrophysiological Aspects

Objectives: To investigate the relationship between neurophysiological sensory and motor nerve function parameters, assessed by nerve conduction studies (NCS) with parasympathetic autonomic function and by heart rate variability (HRV) tests in patients with type 2 diabetes mellitus (T2DM). Material and Methods: A total of 161 T2DM patients underwent NCS. Cardiac autonomic response was assessed by HRV tests to deep breathing (HRV DB), to Valsalva manoeuvre, and during postural change from lying to standing. Results: The amplitude of motor response in the median nerve, tibial nerve, and peroneal nerve was associated with reduced HRV DB (p = 0.0001). The amplitude of motor response in the median nerve, tibial nerve, and peroneal nerve was associated with reduced HRV Valsalva (p = 0.0001). The correlation between the amplitude of response in all sensory nerves (sural, median, and ulnar) and HRV DB was statistically significant (p = 0.0001). Conclusion: The results indicate that there is a correlation in T2DM patients between the damage of small myelinated and unmyelinated nerve fibres from cardiac autonomic nerves, assessed by HRV tests and damage of large motor and sensory fibres, assessed by NCS. Based on the above results, a combination of NCS and HRV tests should be considered in the neurophysiological approach to diabetic neuropathy.

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.

Dependence of Heart Rate Variability Indices on the Mean Heart Rate in Women with Well-Controlled Type 2 Diabetes

Heart rate variability (HRV) is a method used to evaluate the presence of cardiac autonomic neuropathy (CAN) because it is usually attributed to oscillations in cardiac autonomic nerve activity. Recent studies in other pathologies suggest that HRV indices are strongly related to mean heart rate, and this does not depend on autonomic activity only. This study aimed to evaluate the correlation between the mean heart rate and the HRV indices in women patients with well-controlled T2DM and a control group. HRV was evaluated in 19 T2DM women and 44 healthy women during basal supine position and two maneuvers: active standing and rhythmic breathing. Time-domain (SDNN, RMSSD, pNN20) and frequency-domain (LF, HF, LF/HF) indices were obtained. Our results show that meanNN, age, and the maneuvers are the main predictors of most HRV indices, while the diabetic condition was a predictor only for pNN20. Given the known reduced HRV in patients with T2DM, it is clinically important that much of the HRV indices are dependent on heart rate irrespective of the presence of T2DM. Moreover, the multiple regression analyses evidenced the multifactorial etiology of HRV.

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 and heart rate turbulence in patients with vasovagal syncope

Aim    The autonomic nervous system plays an important role in the pathogenesis of vasovagal syncope, but studies on the effect of basal autonomic tone have found confusing results. The aim of this study was to investigate the effect of basal autonomic functions, as assessed by heart rate variability (HRV) and heart rate turbulence (HRT), in patients with vasovagal syncope.Material and methods    Patients who underwent head-up tilt test (HUTT) due to unexplained syncope and who had a 24 hr Holter ECG recording in the same period were retrospectively analyzed. Patients with diabetes, a history of myocardial infarction, heart failure, orthostatic hypotension, atrial fibrillation, or use of vasoactive drugs, such as beta blockers, were excluded from the study. 161 patients who met these criteria were included in the study. Time domain HRV parameters from Holter ECG recordings and HRT parameters from patients with sufficient number of ventricular premature contractions were measured.Results    The age of the patients varied from 16 to 75 yrs (mean: 44.8±18.5 yrs). HUTT results of 60 (37.2 %) patients were evaluated as positive. There were no significant differences in the basal demographic, clinical, or laboratory findings of the tilt-positive and tilt-negative patient groups. Likewise, there were no significant differences between the time domain HRV parameters and HRT parameters of both groups.Conclusion    HRV and HRT parameters reflecting basal autonomic function were not different between HUTT positive and HUTT negative patient groups. These findings suggest that basal autonomic functions have no effect on vasovagal syncope pathogenesis.

Cardiac Autonomic Neuropathy Is Not Reversed by Euglycemia Following Islet Transplantation

BACKGROUND

Cardiac autonomic neuropathy (CAN) is a significant cause of morbidity and mortality for people with type 1 (T1D) and type 2 (T2D) diabetes. Heart rate variability (HRV) has been shown to be a marker of CAN with 24-hour Holter monitoring being a robust modality to assess HRV.

METHODS

To investigate the impact of hypoglycemia on CAN and its potential reversibility with islet transplantation, we compared HRV assessment by 24-hour Holter monitor on a total of 109 subjects from 5 cohorts: (1) T1D with recurrent severe hypoglycemia and on waiting list for islet transplant, (2) T1D following islet cell transplantation (ICT), (3) T2D without hypoglycemia, (4) individuals with prediabetes, and (5) controls without diabetes. SD of the normal-normal interval, square root of the mean squared differences of successive normal-normal intervals (rMSSD) and total spectral power were analyzed.

RESULTS

There was no significant difference in HRV parameters between T1D subjects and T1D post ICT suggesting CAN is not reversible at a median of 4 years postislet transplant. There was a significant difference in controls and T1D in rMSSD and between controls and T2D in total power. The differential effect on rMSSD in T1D and T2D suggests potential greater impact of hypoglycemia on rMSSD.

CONCLUSIONS

Achieving euglycemia after ICT may not reverse CAN once established with no significant difference in HRV parameters at a median of 4 years postislet transplant. Differential effects of T1D as compared with T2D on CAN were identified.

Ethoxyquin is neuroprotective and partially prevents somatic and autonomic neuropathy in db/db mouse model of type 2 diabetes

Ethoxyquin (EQ), a quinolone-based antioxidant, has demonstrated neuroprotective properties against several neurotoxic drugs in a phenotypic screening and is shown to protect axons in animal models of chemotherapy-induced peripheral neuropathy. We assessed the effects of EQ on peripheral nerve function in the db/db mouse model of type II diabetes. After a 7 week treatment period, 12-week-old db/db-vehicle, db/+ -vehicle and db/db-EQ treated animals were evaluated by nerve conduction, paw withdrawal against a hotplate, and fiber density in hindlimb footpads. We found that the EQ group had shorter paw withdrawal latency compared to vehicle db/db group. The EQ group scored higher in nerve conduction studies, compared to vehicle-treated db/db group. Morphology studies yielded similar results. To investigate the potential role of mitochondrial DNA (mtDNA) deletions in the observed effects of EQ, we measured total mtDNA deletion burden in the distal sciatic nerve. We observed an increase in total mtDNA deletion burden in vehicle-treated db/db mice compared to db/+ mice that was partially prevented in db/db-EQ treated animals. These results suggest that EQ treatment may exert a neuroprotective effect in diabetic neuropathy. The prevention of diabetes-induced mtDNA deletions may be a potential mechanism of the neuroprotective effects of EQ in diabetic neuropathy.

[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.

Correlation of staging and risk factors with cardiovascular autonomic neuropathy in patients with type II diabetes mellitus

The impairment of cardiovascular autonomic control among the underdiagnosed complication of diabetes mellitus (DM) with a high prevalence rate of up to 60% in type 2 DM (T2DM). Cardiac autonomic neuropathy (CAN) is an independent risk factor for cardiovascular mortality, arrhythmia, silent ischemia, any major cardiovascular event, and heart failure. We aimed to evaluate cardiovascular autonomic activity by different physiological maneuvers, study risk factors for diabetic CAN including age, gender, duration of diabetes, body mass index (BMI), and glycemic control, and correlate CAN stage with risk factors. One hundred and forty-two T2DM patients consisted of 62 males and 80 females and 100 volunteers as a control sample. Cardiac autonomic functions were assessed by Ewing's tests. Glycated hemoglobin (HbA1c), body weight, height, body mass index (BMI), and waist-hip ratio (WHR) were also measured. Cardiovascular autonomic functions and Ewing scores were significantly different in people with diabetes when compared with control healthy subjects. Ewings test values and Ewing scores were significantly different between diabetics with and without CAN and within patients with different CAN staging. People with diabetes with CAN have a significantly longer duration of disease when compared to those without CAN. A strong association has been found between CAN severity and patient age, duration of disease, HbA1c severity, and the WHR (P < 0.001) but not with BMI. The duration of disease and HbA1c level appear to be associated with the development of CAN (P = 0.001 and P = 0.008, respectively). The poorer glycemic control and the longer the duration of the disease, the higher the prevalence of CAN in T2DM. Age, duration of disease, WHR, and HbA1c are well correlated with the severity of CAN. Parasympathetic impairment is more sensitive to the detection of autonomic dysfunctions than do sympathetic impairment.

Peripheral Nerve Conduction And Sympathetic Skin Response Are Reliable Methods to Detect Diabetic Cardiac Autonomic Neuropathy

AIM

This study aimed to investigate the role of nerve conduction studies (NCS) and sympathetic skin response (SSR) in evaluating diabetic cardiac autonomic neuropathy (DCAN).

METHODS

DCAN was diagnosed using the Ewing test combined with heart rate variability analysis. NCS and SSR were assessed by electrophysiological methods. The association between NCS/SSR and DCAN was assessed via multivariate regression and receiver-operating characteristic analyses.

RESULTS

The amplitude and conduction velocity of the motor/sensory nerve were found to be significantly lower in the DCAN+ group (all P < 0.05). A lower amplitude of peroneal nerve motor fiber was found to be associated with increased odds for DCAN (OR 2.77, P < 0.05). The SSR amplitude was lower while the SSR latency was longer in the DCAN+ group than in the DCAN- group. The receiver-operating characteristic analysis revealed that the optimal cutoff points of upper/lower limb amplitude of SSR to indicate DCAN were 1.40 mV (sensitivity, 61.9%; specificity, 66.3%, P < 0.001) and 0.85 mV (sensitivity, 66.7%; specificity, 68.5%, P < 0.001), respectively. The optimal cutoff points of upper/lower limb latency to indicate DCAN were 1.40 s (sensitivity, 61.9%; specificity, 62%, P < 0.05) and 1.81 s (sensitivity, 69.0%; specificity, 52.2%, P < 0.05), respectively.

CONCLUSIONS

NCS and SSR are reliable methods to detect DCAN. Abnormality in the peroneal nerve (motor nerve) is crucial in predicting DCAN. SSR may help predict DCAN.

Cardiac vagal tone as a novel screening tool to recognize asymptomatic cardiovascular autonomic neuropathy: Aspects of utility in type 1 diabetes

AIMS

To test the performance of the cardiac vagal tone (CVT) derived from a 5-minute ECG recording compared with the standardized cardiovascular autonomic reflex tests (CARTs).

METHODS

Cross-sectional study included 56 well-phenotyped adults with type 1 diabetes (19-71 years, 2-54 years disease-duration). Autonomic testing included: standardized CARTs obtained with the VAGUS™, CVT, and indices of heart rate variability (HRV) obtained at 24- and 120-hour, and electrochemical skin conductance assessed with SUDOSCAN®. ROC AUC and cut-off values were calculated for CVT to recognize CAN based on ≥ 2 (established CAN, n = 7) or 1 (borderline CAN, n = 9) abnormal CARTs and compared to HRV indices and electrochemical skin conductance.

RESULTS

Established CAN: The cut-off CVT value of 3.2LVS showed 67% sensitivity and 87% specificity (p = 0.01). Indices of HRV at either 24-hour (AUC > 0.90) and 120-hour (AUC > 0.88) performed better than CVT. Borderline CAN: The cut-off CVT value of 5.2LVS indicated 88% sensitivity and 63% specificity (p = 0.07). CVT performed better than HRV indices (AUC < 0.72). Electrochemical skin conductance (AUC:0.63-0.72) had lower sensitivity and specificity compared with CVT.

CONCLUSIONS

Implementation of CVT with a clinically applicable cut-off value may be considered a quicker and accessible screening tool which could ultimately decrease the number of unrecognized CAN and initiate earlier prevention initiatives.

Impact of glycemic control over cardiac autonomic neuropathy

Purpose

Cardiovascular autonomic neuropathy (CAN) is one of the most common and serious complications associated with diabetes and is defined as the impairment of the autonomic control of the cardiovascular system, whose prevalence in Indian population has been reported to be > 50%. The risk factors associated with CAN include hyperglycemia, duration of diabetes, hypertension, dyslipidemia, and obesity. This study was conducted to examine the association of CAN with its determinants among diabetics.

Methods

Socio-demographic characteristics were noted alongwith performance of biochemical analyses of blood samples according to standard hospital pathology laboratory protocols. Clinical assessment of CAN comprised a of 5 indexes, including 3 heart rate variability parameters (resting tachycardia, Qtc interval > 440 msec, exercise intolerance) and 2 blood pressure parameters (orthostatic hypotension, abnormal hand gripping test).

Results

The odds of CAN increased with poor glycemic control (FBS ≥ 126 mg/dL (OR = 1.17 (1.02-10.68); 2 hr PPBS ≥ 200 mg/dL (OR 1.63 (1.26-8.82) and HbA1c ≥ 6.5% (OR = 10.68 (1.54-208.02). Significant difference was also found in relation to duration of diabetes, weight and body mass index of the participants with various grades of CAN.

Conclusions

CAN is associated strongly with poor glycemic control. Obesity seems to be involved in the impairments of the cardiac autonomic function and this factor must therefore be taken into account in future studies when interpreting the results. Body mass control and glycemic control could provide an important approach to reducing CAN.

Cardiovascular autonomic neuropathy in patients with type 2 diabetes mellitus and its association with serum omentin and leptin

Cardiovascular autonomic neuropathy (CAN) is a major cause of morbidity and mortality in patients with diabetes as it is associated with a high risk of cardiac arrhythmias.

Autonomic dysfunction in a group of lower extremities arterial disease outpatients

BACKGROUND

The understanding of the specific role of sympathetic neural control and dysregulation in lower extremities arterial disease (LEAD) is still very limited. Aim of our study was to investigate the autonomic profile in LEAD patients and to evaluate if the eventual autonomic alterations were more severe in patients with advanced disease.

METHODS

We enrolled all consecutive outpatients with LEAD referred to our Departments between July 2012 and September 2014. They were compared to a group of matched outpatients without LEAD. All patients underwent Holter ECG monitoring. Time-domain analysis of heart rate variability (HRV) was evaluated.

RESULTS

Compared to controls, patients with LEAD had a lower SDNN (P=0.007) and SDANN (P=0.003). Patients with clinically advanced LEAD had a lower SDNN (P=0.006) and SDANN (P=0.004) compared to LEAD patients with less severe disease and to those without disease.

CONCLUSIONS

LEAD patients had a reduced SDNN and SDANN than patients without LEAD. Autonomic dysfunction was more significant in clinically advanced stages of disease. This association did not relate to ABI value but to clinical stage of disease.

Changes in Myocardial Metabolism Preceding Sudden Cardiac Death

Heart disease is widely recognized as a major cause of death worldwide and is the leading cause of mortality in the United States. Centuries of research have focused on defining mechanistic alterations that drive cardiac pathogenesis, yet sudden cardiac death (SCD) remains a common unpredictable event that claims lives in every age group. The heart supplies blood to all tissues while maintaining a constant electrical and hormonal feedback communication with other parts of the body. As such, recent research has focused on understanding how myocardial electrical and structural properties are altered by cardiac metabolism and the various signaling pathways associated with it. The importance of cardiac metabolism in maintaining myocardial function, or lack thereof, is exemplified by shifts in cardiac substrate preference during normal development and various pathological conditions. For instance, a shift from fatty acid (FA) oxidation to oxygen-sparing glycolytic energy production has been reported in many types of cardiac pathologies. Compounded by an uncoupling of glycolysis and glucose oxidation this leads to accumulation of undesirable levels of intermediate metabolites. The resulting accumulation of intermediary metabolites impacts cardiac mitochondrial function and dysregulates metabolic pathways through several mechanisms, which will be reviewed here. Importantly, reversal of metabolic maladaptation has been shown to elicit positive therapeutic effects, limiting cardiac remodeling and at least partially restoring contractile efficiency. Therein, the underlying metabolic adaptations in an array of pathological conditions as well as recently discovered downstream effects of various substrate utilization provide guidance for future therapeutic targeting. Here, we will review recent data on alterations in substrate utilization in the healthy and diseased heart, metabolic pathways governing cardiac pathogenesis, mitochondrial function in the diseased myocardium, and potential metabolism-based therapeutic interventions in disease.

Aberrant sinus node firing during β-adrenergic stimulation leads to cardiac arrhythmias in diabetic mice

AIM

Cardiovascular complications, including cardiac arrhythmias, result in high morbidity and mortality in patients with type-2 diabetes mellitus (T2DM). Clinical and experimental data suggest electrophysiological impairment of the natural pacemaker of the diabetic heart. The present study examined sinoatrial node (SAN) arrhythmias in a mouse model of T2DM and physiologically probed their underlying cause.

METHODS

Electrocardiograms were obtained from conscious diabetic db/db and lean control db/+ mice. In vivo SAN function was probed through pharmacological autonomic modulation with isoprenaline, atropine and carbachol. Blood pressure stability and heart rate variability (HRV) were evaluated. Intrinsic SAN function was evaluated through ex vivo imaging of spontaneous Ca²⁺ transients in isolated SAN preparations.

RESULTS

While lean control mice showed constant RR intervals during isoprenaline challenge, the diabetic mice experienced SAN arrhythmias with large RR fluctuations in a dose-dependent manner. These arrhythmias were completely abolished by atropine pre-treatment, while carbachol pretreatment significantly increased SAN arrhythmia frequency in the diabetic mice. Blood pressure and HRV were comparable in db/db and db/+ mice, suggesting that neither augmented baroreceptor feedback nor autonomic neuropathy is a likely arrhythmia mechanism. Cycle length response to isoprenaline was comparable in isolated SAN preparations from db/db and db/+ mice; however, Ca²⁺ spark frequency was significantly increased in db/db mice compared to db/+ at baseline and after isoprenaline.

CONCLUSION

Our results demonstrate a dysfunction of cardiac pacemaking in an animal model of T2DM upon challenge with a β-adrenergic agonist. Ex vivo, higher Ca²⁺ spark frequency is present in diabetic mice, which may be directly linked to in vivo arrhythmias.

Prevalence and Correlates of Cardiovascular Autonomic Neuropathy Among Patients with Diabetes in Uganda: A Hospital-Based Cross-sectional Study. Glob Heart. 2020;15:21. [PMID: 32489794 PMCID: PMC7218768 DOI: 10.5334/gh.765]

Background:

Cardiovascular autonomic neuropathy (CAN) is a common complication in individuals with diabetes mellitus (DM) but often overlooked in clinical practice. The burden and correlates of CAN have not been extensively studied in low-income countries, particularly in sub-Saharan Africa.

Objectives:

To determine the prevalence and correlates of CAN among adults in ambulatory diabetes care in southwestern Uganda.

Method:

We conducted a cross-sectional study among adults with diabetes from November 2018 to April 2019. CAN was assessed using the five autonomic function tests: deep breathing, Valsalva maneuver, postural index on standing, change in blood pressure during standing and diastolic blood pressure response to isometric exercise. We estimated the prevalence of CAN and fit regression models to identify its demographic and clinical correlates.

Results:

We enrolled 299 individuals. The mean age was 50.1 years (SD ± 9.8), mean HbA1c was 9.7 (SD ± 2.6) and 69.6% were female. CAN was detected in 156/299 (52.2%) of the participants on the basis of one or more abnormal cardiovascular autonomic reflex tests. Out of 299 participants, 88 (29.4%) were classified as early CAN while 61/299 (20.4%) and 7/299 (2.3%) were classified as definite and severe (advanced) CAN respectively. In multivariable regression models, age over 50 years (aOR 3.48, 95%CI 1.35 –8.99, p = 0.010), duration of diabetes over 10 years (aOR 4.09, 95%CI 1.78 –9.38, p = 0.001), and presence of diabetic retinopathy (aOR 2.25, 95%CI 1.16 –4.34, p = 0.016) were correlated with CAN.

Conclusions:

Our findings reveal a high prevalence of CAN among individuals in routine outpatient care for diabetes mellitus in Uganda. Older age, longer duration of diabetes and coexistence of retinopathy are associated with CAN. Future work should explore the clinical significance and long term outcomes associated with CAN in this region.

Autonomic Nervous System Dysfunction: JACC Focus Seminar

Autonomic nervous system control of the heart is a dynamic process in both health and disease. A multilevel neural network is responsible for control of chronotropy, lusitropy, dromotropy, and inotropy. Intrinsic autonomic dysfunction arises from diseases that directly affect the autonomic nerves, such as diabetes mellitus and the syndromes of primary autonomic failure. Extrinsic autonomic dysfunction reflects the changes in autonomic function that are secondarily induced by cardiac or other disease. An array of tests interrogate various aspects of cardiac autonomic control in either resting conditions or with physiological perturbations from resting conditions. The prognostic significance of these assessments have been well established. Clinical usefulness has not been established, and the precise mechanistic link to mortality is less well established. Further efforts are required to develop optimal approaches to delineate cardiac autonomic dysfunction and its adverse effects to develop tools that can be used to guide clinical decision-making.