Cardiovascular autonomic neuropathy in patients with type 2 diabetes

The Effect of Exercise on Cardiovascular Autonomic Nervous Function in Patients with Diabetes: A Systematic Review

BACKGROUND

Diabetic neuropathy, including autonomic neuropathy, is a severe complication in patients with poorly controlled diabetes. Specifically, cardiovascular autonomic neuropathy (CAN) plays a significant prognostic role in cardiovascular morbidity and mortality. Exercise, an essential component of diabetes treatment, may have a therapeutic effect on patients with diabetes complicated by CAN. However, it remains unclear whether exercise has a therapeutic or protective effect in diabetes patients with CAN.

METHODS

The author conducted a systematic search of PubMed/MEDLINE, Embase, and The Cochrane Library, resulting in the identification of eight eligible randomized controlled trials for this review.

RESULTS

Exercise, including aerobic exercise combined with resistance training (RT), high-intensity interval training, and progressive RT, has shown a beneficial effect on cardiac autonomic function (CAF) in patients with type 2 diabetes, as measured by heart rate variability, heart rate recovery, and baroreflex sensitivity. However, most studies had low quality. Moreover, there were no relevant studies examining the effect of exercise on CAF in older patients, patients with poorly controlled diabetes, and patients with type 1 diabetes.

CONCLUSIONS

Exercise has the potential to manage patients with CAN by balancing sympathetic and parasympathetic nervous system functions; however, further studies are warranted in the future.

Impact of blood glucose control on sympathetic and vagus nerve functional status in patients with type 2 diabetes mellitus

AIMS

Present study observed the impact of blood glucose control on sympathetic and vagus functional status in type 2 diabetes mellitus (DM) patients through observing the association between glycosylated hemoglobin (HbA1c) level and sympathetic and vagus functional status detected by heart rate recovery (HRR) and heart rate variability (HRV) assessments.

METHODS

Consecutive hospitalized DM patients were divided into well glycemic control group (HbA1c < 7.0%, group WGC, n = 100) and poor glycemic control group (HbA1c ≥ 7.0%, group PGC, n = 100), 100 hospitalized patients without DM served as control group (group C). All subjects underwent blood biochemistry test, treadmill exercise testing and 24-h Holter monitoring.

RESULTS

HRR and HRV parameters were significantly lower in group WGC and PGC than in group C. Standard deviation of NN intervals (SDNN), standard deviation of all 5-min average NN intervals (SDANN), very low frequency (VLF) values were significantly lower in group PGC than in group WGC. HbA1c level was negatively correlated with HRR1, SDNN, SDANN, VLF, low frequency and high frequency. Logistic regression analysis showed that lower SDNN, SDANN and VLF values were risk factors for high HbA1c levels in DM patients after adjusting for gender, age and beta-blocker use in the model 1, and for gender, age, beta-blocker use, coronary artery disease and hypertension in the model 2.

CONCLUSIONS

Present results indicate that sympathetic and vagal functional status are impaired independent of HbA1c level, while poor glycemic control is related to more significant neurocardiac dysfunction in DM patients.

Association between heart rate recovery after exercise and renal function in patients referred for treadmill exercise test

Introduction

Heart rate recovery (HRR) is a marker of parasympathetic activity recovery after exercise, and it is associated with cardiovascular mortality and total mortality. Impaired renal function is also associated with cardiac mortality. The aim of this study was to investigate the association between HRR after exercise and renal function in patients referred for a treadmill exercise test.

Patients and methods

This cross-sectional study was conducted at a regional hospital in southern Taiwan. Patients who completed a symptom-limited treadmill exercise test from January 2015 to February 2018 were recruited. Before the treadmill exercise test, patients were asked to complete a questionnaire on the past disease history and lifestyle factors. Serum creatinine measurement within two years prior to or after the date of the treadmill exercise test of the patients was also obtained from the medical records for these patients. Estimated glomerular filtration rate (eGFR) was calculated. Simple and multiple linear regression analyses were performed to investigate the association between one-minute HRR and eGFR.

Results

A total of 2,825 patients completed the treadmill exercise test, and serum creatinine measurement was identified from medical records for 2,153 patients (76.2%). Multiple linear regression analysis revealed that a lower eGFR was significantly associated with lower one-minute HRR (P< 0.001), adjusting for other significant independent factors, including age, waist circumference, type 2 diabetes mellitus, and smoking.

Conclusions

In this cross-sectional observational study, a lower eGFR was significantly and independently associated with decreased one-minute HRR, suggesting that parasympathetic activity recovery after exercise could be impaired by a decrease in renal function.

Farnesoid X receptor interacts with cAMP response element binding protein to modulate glucagon-like peptide-1 (7-36) amide secretion by intestinal L cell

Type II diabetes is a complex, chronic, and progressive disease. Glucagon-like peptide-1 (7-36) amide (GLP-1) is a gut hormone released from the L cells which stimulate insulin secretion and promotes insulin gene expression and β-cell growth and differentiation. Elevated levels of hormones secreted by L cells are an essential reason for diabetes improvement. GLP-1 secretion has been reported to be regulated by farnesoid X receptor (FXR), a transcriptional sensor for bile acids which also acts on glucose metabolism. Herein, we attempted to evaluate the effect of FXR on GLP-1 secretion in mouse enteroendocrine L cell line, namely STC-1, and to investigate the underlying mechanism. FXR inversely regulated GLP-1 secretion in STC-1. A total of 24 nonredundant human proteins were shown to be related to FXR by BioGRID; KEGG pathway analysis revealed that FXR was related to glucagon signaling pathway, particularly with the transcriptional activators CREB, PGC1α, Sirt1, and CBP. CREB could positively regulate GLP-1 secretion in STC-1 cells. FXR combined with CREB to inhibit its transcriptional activity, thus inhibiting proprotein convertase subtilisin/kexin type 1 protein level and GLP-1 secretion. In the present study, we demonstrated a negative regulation of GLP-1 secretion by FXR in L cell line, STC-1; FXR exerts its function in L cells through interacting with CREB, a crucial transcriptional regulator of cAMP-CREB signaling pathway, to inhibit its transcriptional activity. Targeting FXR to rescue GLP-1 secretion may be a promising strategy for type II diabetes.

Are Twenty-Four Sessions of Aerobic Exercise Sufficient for Improving Cardiac Parameters in Diabetes Mellitus? A Randomized Controlled Trial

Background: Diabetes is a chronic disease that reduces cardiorespiratory fitness and increases systolic and diastolic blood pressures as well as resting heart rate due to the activity level of the sympathetic nervous system. The aim of this study was to assess the effectiveness of 2 types of aerobic exercise, with and without external loading, on cardiac parameters in diabetic patients. Methods: This randomized controlled trial was carried out on 45 volunteers. These individuals were randomly divided into aerobic, weighted vest, and control groups. The aerobic protocol comprised 24 sessions of aerobic exercise. The exercise program for the weighted vest group was identical to that of the aerobic group, except that the subjects wore a weighted vest. The parameters were measured before and after the 24 sessions. Results: The mean age of the study population was 48.30±5.02 years in the aerobic group, 48.33±5.74 years in the weighted vest group, and 48.60±4.79 years in the control group. Males comprised 7 (53.8%) patients in the aerobic group, 7 (58.3%) in the weighted vest group, and 8 (53.3%) in the control group. After 8 weeks, maximum oxygen consumption in the aerobic group (mean±SD=37.54±8.02 mL/kg/min, 95% CI: 5.48 to 11.60; P<0.001) and the weighted vest group (mean±SD=35.92±3.96 mL/kg/min, 95% CI: 4.36 to 9.64; P<0.001) was increased, similar to metabolic equivalent of task in the aerobic group (mean±SD=11.60±1.62 kcal/kg×h, 95% CI: 1.48 to 2.72; P<0.001) and the weighted vest group (mean±SD=11.21±1.11 kcal/kg×h, 95% CI: 1.23 to 2.28; P<0.001). Furthermore, resting heart rate decreased significantly in the aerobic group (mean ± SD=90.23±8.90 bpm, 95% CI: -13.93 to -1.29; P=0.022) and the weighted vest group (mean±SD=90.58±9.19 bpm, 95% CI: -0.16 to - 12.33; P=0.045). Conclusion: These findings suggest that 24 aerobic exercise sessions might improve cardiac parameters in type 2 diabetes.

Exercise training and cardiac autonomic function in type 2 diabetes mellitus: A systematic review

Cardiac autonomic neuropathy (CAN) is a common complication of type 2 diabetes mellitus (T2DM). It has been found to independently predict all cause and cardiovascular disease (CVD) mortality. It remains unclear whether exercise training could improve autonomic control in T2DM patients. The purpose of this study was to systematically review the effects of exercise training on cardiac autonomic function in T2DM patients. Electronic databases (MEDLINE, CENTRAL, PEDro, Scopus and Web of science) were systematically searched to retrieve relevant evidence. Clinical trials administering exercise training for at least 4 weeks and examining either heart rate variability (HRV), baroreflex sensitivity (BRS), heart rate recovery (HRR) as outcome measures were eligible. Eighteen articles were found to be relevant and were then assessed for characteristics and quality. Fifteen studies out of 18 found that exercise training leads to positive improvements in autonomic function of T2DM patients. Exercise participation enhances cardiac autonomic function of type 2 diabetics and therefore should be implemented in their management programs.

Coadjuvants in the Diabetic Complications: Nutraceuticals and Drugs with Pleiotropic Effects

Because diabetes mellitus (DM) is a multifactorial metabolic disease, its prevention and treatment has been a constant challenge for basic and clinical investigators focused on translating their discoveries into clinical treatment of this complex disorder. In this review, we highlight recent experimental and clinical evidences of potential coadjuvants in the management of DM, such as polyphenols (quercetin, resveratrol and silymarin), cultured probiotic microorganisms and drugs acting through direct/indirect or pleiotropic effects on glycemic control in DM. Among several options, we highlight new promising therapeutic coadjuvants, including chemical scavengers, the probiotic kefir and the phosphodiesterase 5 inhibitors, which besides the reduction of hyperglycemia and ameliorate insulin resistance, they reduce oxidative stress and improve endothelial dysfunction in the systemic vascular circulation. In the near future, experimental studies are expected to clear the intracellular pathways involving coadjuvants. The design of clinical trials may also contribute to new strategies with coadjuvants against the harmful effects of diabetic complications.

Cardiovascular autonomic neuropathy in patients with type 2 diabetes

AIMS/INTRODUCTION

Heart rate recovery (HRR) after exercise is considered to be a new index of autonomic dysfunction associated with cardiovascular disease and mortality. The present study aimed to investigate the risk factors of HRR and the effects of exercise on the abnormal HRR in type 2 diabetes.

MATERIALS AND METHODS

A total of 123 type 2 diabetes patients were recruited, and the oral glucose tolerance test and exercise test were carried out to analyze the risk factors associated with abnormal HRR. Among these patients, 42 patients with abnormal HRR were further randomized to either the conventional therapy group (CT group; n = 20) or the intensive therapy group (IT group; n = 22). The CT group patients underwent metformin and diet control, whereas the IT group additionally underwent a combined moderate intensity aerobic and resistance training three times per week for 12 weeks. The results of blood sample analysis and HRR were recorded before and after the training.

RESULTS

Abnormal HRR was related to fasting blood glucose, glycosylated hemoglobin, low-density lipoprotein cholesterol, and resting and maximum heart rates (P < 0.05 for both). After training, the IT group had significantly lower levels of fasting blood glucose, glycosylated hemoglobin and resting heart rate than the CT group (all P < 0.01 or P < 0.005). Significant improvement in HRR and metabolic equivalents was observed in the IT group compared with the CT group (P < 0.05).

CONCLUSIONS

These data suggested that combined aerobic and resistance training improved cardiac autonomic dysfunction as measured by HRR in type 2 diabetes patients. This might be due to better improvement of glycemic control, resting heart rate and physical fitness.