High prevalence and early onset of cardiac autonomic neuropathy among South Indian type 2 diabetic patients with nephropathy

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

INTRODUCTION

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

METHODOLOGY

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

RESULTS

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

CONCLUSION

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

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.

Design and validation of a scoring model for differential diagnosis of diabetic nephropathy and nondiabetic renal diseases in type 2 diabetic patients

BACKGROUND

We aim to design a scoring model for differential diagnosis between diabetic nephropathy (DN) and nondiabetic renal disease (NDRD) in type 2 diabetic patients through a combination of clinical variables.

METHODS

A total of 170 patients with type 2 diabetes who underwent kidney biopsies were included and divided into three groups according to pathological findings: DN group (n = 46), MIX group (DN + NDRD, n = 54), NDRD group (n = 70). Clinical characteristics and laboratory data were collected and compared among groups. Variables with a significant statistical difference between DN and NDRD patients were analyzed by logistic regression to predict the presence of NDRD; then a scoring model was established based on the regression coefficient and further validated in an independent cohort of 67 patients prospectively.

RESULTS

On biopsy, 72.9% of patients had NDRD, and the most common pathological type was membranous nephropathy. The established scoring model for predicting NDRD included five predictors: age, systolic blood pressure, hemoglobin, duration of diabetes, and absence of diabetic retinopathy. The model demonstrated good discrimination and calibration (area under curve [AUC] 0.863, 95% CI, 0.800-0.925; Hosmer-Lemeshow [H-L] P = .062). Furthermore, high prediction accuracy (AUC = 0.900; 95% CI, 0.815-0.985) in the validation cohort proved the stability of the model.

CONCLUSIONS

We present a simple, robust scoring model for predicting the presence of NDRD with high accuracy (0.85) for the first time. This decision support tool provides a noninvasive method for differential diagnosis of DN and NDRD, which may help clinicians assess the risk-benefit ratio of kidney biopsy for type 2 diabetic patients with renal impairment.

Cardiac autonomic neuropathy in patients with type 2 diabetes mellitus having peripheral neuropathy: A cross-sectional study

AIMS

The aim was to see the frequency of CAN in type 2 diabetes mellitus patients with peripheral neuropathy, and its association with peripheral nerve conduction abnormalities.

METHODS

A cross-sectional study at BIRDEM was conducted in 62 patients with type 2 diabetes mellitus having electrophysiologically diagnosed peripheral neuropathy. CAN was detected by four clinical tests - heart rate response to deep breathing and valsalva maneuver, blood pressure response to standing and sustained handgrip.

RESULT

The study showed that all patients had CAN - 14.52% had early, 26.67% had definitive and 59.68% had severe CAN. Patients with severe CAN had significantly reduced nerve conduction velocity and amplitude of peripheral nerves (sural 4.36 ± 12.77 vs 9.65 ± 17.77 m/s, p = 0.009; 2.23 ± 1.89 vs 3.01 ± 2.76 mV, p = 0.001; peroneal 7 ± 4.23 vs 8.53 ± 5.99 mV, p = 0.047; tibial 0.008 ± 0.03 vs 0.026 ± 0.05 mV, p = 0.009) and higher serum triglyceride levels (221.17 ± 120.61 vs 197.76 ± 68.43 mg/dl, p = 0.033).

CONCLUSION

Diabetic patients with peripheral neuropathy have CAN, the severity of which increases with worsening neuropathy.

Epidemiology of microvascular complications of diabetes in South Asians and comparison with other ethnicities

Type 2 diabetes mellitus is widely prevalent in South Asians, and has a significant effect on health, as well as the economies of South Asian countries, particularly when the disease is associated with complications. There are certain characteristics associated with the South Asian phenotype that make South Asians especially prone to diabetes, as well as its complications. Microvascular complications cause considerable morbidity and mortality. There are significant differences in the epidemiology of microvascular complications between South Asians and people of other races. There is evidence of higher prevalence of nephropathy and retinopathy in South Asians compared with Caucasians; however, recent studies indicate that this trend seems to be leveling off. Importantly, diabetic neuropathy occurs less frequently in South Asians compared with Caucasians. These observations have important implications in managing South Asian patients with diabetes and microvascular complications.

Inverse association between serum total bilirubin levels and diabetic peripheral neuropathy in patients with type 2 diabetes

Several studies have suggested that bilirubin, a potent innate antioxidant, plays a protective role against cardiovascular and microvascular disease. This study investigated the association between serum concentrations of total bilirubin (TB) and the presence of diabetic peripheral neuropathy (DPN) in Korean diabetic patients. This cross-sectional study involved 1207 patients aged more than 30 years with type 2 diabetes. DPN was assessed according to clinical symptoms and physical examinations using Michigan Neuropathy Screening Instrument examination score, 10-g monofilament sensation, and current perception threshold. The subjects were stratified into gender-specific tertiles based on TB values, and the relationship between the TB values and DPN was analyzed. Compared with patients within the lowest TB tertile, those with higher TB levels consisted of patients with shorter duration of diabetes, lower HbA1c, better renal function, and less autonomic neuropathy, retinopathy, and albuminuria. Serum TB levels were inversely associated with DPN. In multivariate analysis for the development of DPN after adjusting for potential confounding factors including retinopathy, albuminuria, and autonomic neuropathy, the TB levels were inversely associated with the presence of DPN, both as a continuous variable [odds ratio (OR) per log standard deviation (SD) 0.79; 95% confidence interval (CI) 0.65-0.97; P = 0.022] and when categorized in tertiles (the highest vs. the lowest tertile; OR 0.63; 95% CI 0.40-0.99; P = 0.046). Low serum bilirubin levels are significantly associated with DPN, independently of classic risk factors and other microvascular complications. Further investigation is necessary to determine whether serum bilirubin has a prognostic significance on DPN.

Identifying Common Genetic Risk Factors of Diabetic Neuropathies

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

Cardiovascular autonomic dysfunction predicts severe hypoglycemia in patients with type 2 diabetes: a 10-year follow-up study

OBJECTIVE The aim of this study was to investigate the development of severe hypoglycemia (SH) in the presence of cardiovascular autonomic neuropathy (CAN) in patients with type 2 diabetes. RESEARCH DESIGN AND METHODS From January 2001 to December 2002, a total of 894 patients with type 2 diabetes were enrolled. A cardiovascular autonomic function test (AFT) was performed using the following heart rate variability parameters: expiration-to-inspiration ratio, response to Valsalva maneuver, and standing. From the results for each of the three tests (0 for normal, 1 for abnormal), a total AFT score of 1 was defined as early CAN, and an AFT score of ≥2 was defined as definite CAN. RESULTS The median follow-up time was 9.5 years. The mean age was 54.5 ± 10.1 years, and the mean duration of diabetes was 8.9 ± 6.3 years. One hundred ninety-six patients (31.4%) showed an abnormal cardiovascular AFT score at baseline. Sixty-two patients (9.9%) experienced 77 episodes of SH (1.33 per 100 patient-years). The number of SH events increased as the CAN score increased (23 patients [5.4%] with normal score; 17 patients [17.2%] with early CAN; and 22 patients [22.7%] with definite CAN; P for trends < 0.001). Cox proportional hazards regression analysis revealed that SH was associated with definite CAN (normal vs. definite CAN: hazard ratio 2.43 [95% CI 1.21-4.84]; P = 0.012). CONCLUSIONS Definite CAN was an independent prognostic factor for the development of SH in patients with type 2 diabetes.

Cardiovascular autonomic neuropathy in context of other complications of type 2 diabetes mellitus

The aim of this study was to investigate the relationship between cardiac autonomic neuropathy (CAN) and other micro- and macrovascular complications and risk factors for type 2 diabetes. We included, in this study, 149 patients with type 2 diabetes. We evaluated their cardiovascular risk factors, demographic data, and any major micro- and macrovascular complications of their diabetes. Assessments of CAN were based upon Ewing's battery.

RESULTS

CAN was present in 38.9% of patients. In the CAN group, the duration of diabetes, BMI, systolic blood pressure, lipid levels, and HBA1c were all significantly higher than those in the other group. A significant association was found between CAN and retinopathy, peripheral neuropathy, ABI, and IMT. Multivariate logistic regression demonstrated that, in type 2 diabetes, the odds of CAN (OR (95% confidence intervals)) increase with the age of the patients (1.68 (1,4129-2.0025)), the average diabetes duration (0.57 (0.47-0.67)), cholesterol (1.009 (1.00-1.01)), HbA1c levels (1.88 (1.31-2.72)), peripheral neuropathy (15.47 (5.16-46.38)), BMI (1.12 (1.05-1.21)), and smoking (2.21 (1.08-4.53)).

CONCLUSIONS

This study shows that CAN in type 2 diabetes is significantly associated with other macro- and microvascular complications and that there are important modifiable risk factors for its development.

Diabetic peripheral neuropathy is associated with increased arterial stiffness without changes in carotid intima-media thickness in type 2 diabetes

OBJECTIVE

This study was conducted to investigate the association of diabetic peripheral neuropathy (DPN) with both arterial stiffness and intima-media thickness (IMT).

RESEARCH DESIGN AND METHODS

We conducted a cross-sectional analysis of 731 subjects with type 2 diabetes. DPN was diagnosed on the basis of neuropathic symptoms, insensitivity to a 10-g monofilament, abnormal pin-prick sensation, and abnormal current perception threshold. Arterial stiffness was assessed by cardio-ankle vascular index (CAVI), and IMT was assessed by B-mode ultrasonography.

RESULTS

Patients with DPN had higher CAVI than those without DPN in multivariate-adjusted models, whereas no differences in IMT were observed between patients with and without DPN after adjustment for age and sex. In the multivariate analysis, CAVI was a significant determinant of DPN (odds ratio 1.36 [95% CI 1.13-1.65], P = 0.001).

CONCLUSIONS

DPN is significantly associated with arterial stiffness without carotid intimal changes in patients with type 2 diabetes.

Cardiovascular autonomic neuropathy, autonomic symptoms and diabetic complications in 674 type 2 diabetes

AIMS

To determine the relationships between cardiovascular autonomic neuropathy (CAN) and autonomic symptoms, clinical parameters and diabetic complications in type 2 diabetes (T2DM).

METHODS

The results of autonomic symptoms, clinical parameters, diabetes complications and cardiovascular reflex (CVR) tests of 674 T2DM were analyzed.

RESULTS

Significant correlations were found between CAN risk and age (p=0.019), duration of diabetes (p=0.008), HbA1c (p<0.001), systolic blood pressure (p=0.006), nephropathy (p<0.001), retinopathy (p<0.001), and QTc interval (p<0.001), but not BMI and hyperlipidemia. Patients with retinopathy or proteinuria had increase risk of CAN, and proliferative diabetic retinopathy (PDR) was the most significant risk factor (odds ratio: 6.85; 95% CI: 2.32-20.20) for CAN. Eighty-three percent of patients complained of autonomic symptoms; and the more symptoms complained, the higher the prevalence of CAN. Impotence was the only single symptom associated with CAN risk. Additional CAN risks were also observed when patients with multiple symptoms and/or complications in combinations.

CONCLUSIONS

Our results implied that patients with multiple symptoms and/or complications in combinations have increased CAN risk, and this may provide additional information for clinicians to identify T2DM at risk of having CAN.

Increasing severity of cardiac autonomic neuropathy is associated with increasing prevalence of nephropathy, retinopathy, and peripheral neuropathy in Turkish type 2 diabetics

BACKGROUND

Cardiac autonomic neuropathy (CAN) is the most frequent and clinically important form of diabetic autonomic neuropathy. CAN is associated with increased frequency of other microvascular complications of diabetes mellitus (DM). In this study, we evaluated the prevalence diabetic nephropathy, retinopathy, and peripheral neuropathy, and measured gastric emptying time and bladder emptying time in type 2 diabetic patients with varying degrees of CAN.

PATIENTS AND METHODS

Fifty-three patients with DM complicated by CAN (30 women and 23 men; mean age, 58.8+/-9.15 years; duration of diabetes, 13.9+/-7.7 years) were included in this study. The patients were grouped according to the degree of CAN as early, definite, and severe CAN.

RESULTS

There were significant differences regarding the prevalence of nephropathy, retinopathy, and peripheral neuropathy diagnosed by EMG among those groups (P<.05). However, there was no significant difference regarding the prevalence of peripheral neuropathy diagnosed by neurological examination (P>.05), and scintigraphic measurements of gastric and bladder emptying time were comparable among the groups (P>.05).

CONCLUSION

The prevalence of other diabetic microvascular complications increase as the severity of CAN increases in patients with type 2 DM. This study emphasizes the need for an early screening for peripheral neuropathy, retinopathy, and nephropathy in type 2 diabetic patients with CAN, especially with severe involvement.

Cardiac autonomic neuropathy in diabetes mellitus: prevalence, risk factors and utility of corrected QT interval in the ECG for its diagnosis

OBJECTIVES

To study the prevalence and risk factors for cardiac autonomic neuropathy (CAN) and the utility of prolongation of corrected QT interval (QTc) in the ECG to diagnose CAN in patients with diabetes mellitus.

DESIGN AND SETTING

Cross-sectional study conducted among patients attending the diabetic clinic of a teaching hospital.

METHODS

The prevalence of CAN among 100 patients with type 1 and type 2 diabetes mellitus was assessed by the five autonomic function tests by Eving's methodology. The CAN score in each patient and its relationship to the QTc interval were analysed. Possible influences of age, duration of diabetes and coexistent peripheral neuropathy on the occurrence of CAN also were studied.

RESULTS

The prevalence of CAN was 60%. Univariate analysis showed a significant association between CAN and higher age (odds ratio (OR) 15.75), prolongation of QTc (OR 5.55), duration of disease over 10 years (OR 2) and peripheral neuropathy (p<0.001) in patients with type 1 diabetes. Significant risks for CAN among patients with type 2 diabetes were coexistent peripheral neuropathy (OR 14), prolonged QTc (OR 9.75), higher age (OR 7.2) and disease duration over 10 years (OR 1.92) in univariate analysis, but none of them showed independent risk in multivariate analysis. Disease duration over 10 years resulted in QTc prolongation in a significant numbers of cases with type 1 (p<0.001) and type 2 (p = 0.006) diabetes. The sensitivity, specificity and positive predictive value of QTc prolongation for the diagnosis of CAN were 77%, 62.5% and 77% in type 1 and 76.5%, 75% and 81.3% in type 2, respectively. Higher CAN scores correlated with longer QTc intervals (coefficient of correlation 0.73; p<0.001).

CONCLUSIONS

The prevalence of CAN in diabetes mellitus is high. Higher age, longer duration of diabetes and peripheral neuropathy are significant risk factors. QTc interval in the ECG can be used to diagnose CAN with reasonable sensitivity, specificity and positive predictive value.

Diabetic microvascular complications--can the presence of one predict the development of another?

The number of people with diabetes is increasing dramatically worldwide. The rising prevalence of obesity in childhood and adolescence has also been linked to a startling increase in the number of diagnosed cases of type 2 diabetes in these younger age groups. Despite the introduction of treatment strategies, diabetes remains a major cause of new-onset blindness, end-stage renal disease, and lower leg amputation, all of which contribute to the excess morbidity and mortality in people with diabetes. Furthermore, the management of diabetes-related complications generates substantial costs. In order that timely treatment can be given, it is essential that patients at risk for the development of diabetic microvascular complications are identified earlier. Diabetes duration and glycemic, blood pressure, and lipid control have consistently been shown to correlate with diabetic retinopathy, neuropathy, and nephropathy, but to date, the relationship of one diabetic microvascular complication to another has not been clearly described. A review of the literature has raised the question that apart from other known risk factors, there is a possible relationship among the diabetic microvascular complications themselves, and this appears to be much stronger than the sparse published data on it would suggest. A scoring system that can predict the development of diabetic microvascular complications may facilitate the early identification of those patients at risk and, consequently, have a positive impact on patients' quality of life and reduce the economic burden of diabetes and its complications.

Right-left correlation of the sympathetically induced fluctuations of photoplethysmographic signal in diabetic and non-diabetic subjects

Photoplethysmography (PPG) records the cardiac-induced changes in tissue blood volume by light-transmission measurements. The baseline and amplitude of the PPG signal show very low-frequency (VLF) spontaneous fluctuations, which are mediated by the sympathetic nervous system, and high correlation between right and left extremities of healthy subjects. As sympathetic neuropathy is one of the diabetic complications, the right-left correlation of the PPG fluctuations was examined in diabetic patients. The PPG signal was simultaneously measured in the two index fingers and the two second toes of 35 diabetic patients and 33 non-diabetic subjects. For each PPG pulse, the baseline and amplitude were determined, and the right-left correlation coefficients of the VLF fluctuations in the baseline and amplitude were derived. The VLF fluctuations in the baseline showed high right-left correlation, both for fingers (0.93 +/- 0.05) and toes (0.93 +/- 0.06), for the non-diabetic subjects, and significantly lower correlation (0.78 +/- 0.22 and 0.84 +/- 0.17, respectively) for the diabetic patients. Similar results were obtained for the amplitude VLF fluctuations. The right-left correlation coefficients for diabetic patients decreased with the disease duration for the toe baseline and toe amplitude fluctuations and correlated with heart rate response to deep breathing for the finger baseline and toe amplitude fluctuations. The right-left correlation coefficients of the PPG fluctuations provide a simple and convenient means for assessing the adequacy of the sympathetic nervous system function.

Abnormal cardiovascular reflex tests are predictors of mortality in Type 2 diabetes mellitus

AIMS

To determine whether diabetic autonomic neuropathy is an important factor contributing to mortality in Type 2 diabetes mellitus.

METHODS

Between 1989 and 1993, 431 men and 181 women with Type 2 diabetes were given diabetic autonomic neuropathy cardiovascular reflex (CVR) tests. These subjects were followed for the subsequent 5--9 years to assess mortality rates.

RESULTS

The prevalence rate of abnormal CVR tests was 46.1% in patients with the history of diabetes less than 5 years and up to 69.4% when the history of diabetes exceeded 20 years. During the follow-up period from 1 January 1989 to 31 December 1997 (mean 7.7 years), a total of 135 participants died. The 8-year survival rate for patients with abnormal CVR tests was 63.6% in males and 76.4% in females, compared with 80.9 and 93.3% for patients with normal CVR tests. The results were grouped as: group 1, normal CVR tests without postural hypotension (PHT); group 2, normal CVR tests with PHT; group 3, abnormal CVR tests without PHT; and group 4, abnormal CVR tests with PHT. The 8-year survival rate was 85.4% in group 1, 80.9% in group 2, 74.5% in group 3 and 61.1% in group 4.

CONCLUSION

Type 2 diabetic patients with abnormal CVR tests may have increased mortality, and those combined with postural hypotension have higher mortality than those without. Abnormal CVR tests may be important predictors of mortality in Type 2 diabetes mellitus.