Diabetic autonomic neuropathy does not impede improvement in hypoglycaemia awareness in adults: Sub-study results from the HypoCOMPaSS trial

AIMS

Impaired awareness of hypoglycaemia (IAH) increases the risk of severe hypoglycaemia in people with type 1 diabetes mellitus (T1DM). IAH can be reversed through meticulous avoidance of hypoglycaemia. Diabetic autonomic neuropathy (DAN) has been proposed as an underlying mechanism contributing to IAH; however, data are inconsistent. The aim of this study was to examine the effects of cardiac autonomic neuropathy (CAN) on IAH reversibility inT1DM.

METHODS

Participants with T1DM and IAH (Gold score ≥4) recruited to the HypoCOMPaSS (24-week 2 × 2 factorial randomised controlled) trial were included. All underwent screening for cardiac autonomic function testing at baseline and received comparable education and support aimed at avoiding hypoglycaemia and improving hypoglycaemia awareness. Definite CAN was defined as the presence of ≥2 abnormal cardiac reflex tests. Participants were grouped according to their CAN status, and changes in Gold score were compared.

RESULTS

Eighty-three participants (52 women [62.7%]) were included with mean age (SD) of 48 (12) years and mean HbA1c of 66 (13) mmol/mol (8.2 [3.3] %). The mean duration of T1DM was 29 (13) years. The prevalence of CAN was low with 5/83 (6%) participants having definite autonomic neuropathy with 11 (13%) classified with possible/early neuropathy. All participants, regardless of the autonomic function status, showed a mean improvement in Gold score of ≥1 (mean improvement -1.2 [95% CI -0.8, -1.6]; p < 0.001).

CONCLUSIONS

IAH can be improved in people with T1DM, and a long duration of disease, with and without cardiac autonomic dysfunction. These data suggest that CAN is not a prime driver for modulating IAH reversibility.

Rectal sensitivity correlated with gastrointestinal-mediated glucose disposal, but not the incretin effect

OBJECTIVE

The mechanisms behind the diminished incretin effect in type 2 diabetes are uncertain, but impaired vagal transmission has been suggested. We aimed to investigate the association between the incretin effect and autonomic neuropathy, and the degree of dysglycaemia and duration of diabetes.

DESIGN AND METHODS

For a cross-sectional study, we included participants with either longstanding type 2 diabetes, recent onset, untreated diabetes and controls without diabetes matched for age, sex and body mass index. Autonomic nerve function was assessed with cardiovascular reflex tests, heart rate variability and sudomotor function. Visceral afferent nerves in the gut were tested performing rapid rectal balloon distention. An oral glucose tolerance test and an intravenous isoglycaemic glucose infusion were performed to calculate the incretin effect and gastrointestinal-mediated glucose disposal (GIGD).

RESULTS

Sixty-five participants were recruited. Participants with diabetes had rectal hyposensitivity for earliest sensation (3.7 ± 1.1 kPa in longstanding, 4.0 ± 1.3 in early), compared to controls (3.0 ± 0.9 kPa), p = .005. Rectal hyposensitivity for earliest sensation was not associated with the incretin effect (rho = -0.204, p = .106), but an association was found with GIGD (rho -0.341, p = .005). Incretin effect and GIGD were correlated with all glucose values, HbA1c and duration of diabetes.

CONCLUSIONS

Rectal hyposensitivity was uncovered in both longstanding and early type 2 diabetes, and was not associated with the incretin effect, but with GIGD, implying a potential link between visceral neuropathy and gastrointestinal handling of glucose. Both the incretin effect and GIGD were associated with the degree of dysglycaemia and the duration of diabetes.

PREVIOUSLY PUBLISHED

Some of the data have previously been published and presented as a poster on the American Diabetes Association 83rd Scientific Sessions: Meling et al; 1658-P: Rectal Hyposensitivity, a Potential Marker of Enteric Autonomic Nerve Dysfunction, Is Significantly Associated with Gastrointestinally Mediated Glucose Disposal in Persons with Type 2 Diabetes. Diabetes 20 June 2023; 72 (Supplement_1): 1658-P. https://doi.org/10.2337/db23-1658-P.

Cardiovascular autonomic neuropathy in patients with type 2 diabetes with and without sensorimotor polyneuropathy

BACKGROUND AND AIMS

Cardiovascular autonomic neuropathy (CAN) in patients with diabetes is associated with poor prognosis. We aimed to assess signs of CAN and autonomic symptoms and to investigate the impact of sensorimotor neuropathy on CAN by examining type 2 diabetes patients with (DPN [distal sensorimotor polyneuropathy]) and without distal sensorimotor polyneuropathy (noDPN) and healthy controls (HC). Secondarily, we aimed to describe the characteristics of patients with CAN.

METHODS

A population of 374 subjects from a previously described cohort of the Danish Centre for Strategic Research in Type 2 Diabetes (DD2) were included. Subjects were examined with the Vagus™ device for the diagnosis of CAN, where two or more abnormal cardiovascular autonomic reflex tests indicate definite CAN. Autonomic symptoms were assessed with Composite Autonomic Symptom Score 31 (COMPASS 31) questionnaire. DPN was defined according to the Toronto consensus panel definition.

RESULTS

Definite CAN was present in 22% with DPN, 7% without DPN and 3% of HC, and 91% of patients with definite CAN had DPN. Patients with DPN and definite CAN reported higher COMPASS 31 scores compared to patients with noDPN (20.0 vs. 8.3, p < 0.001) and no CAN (22.1 vs. 12.3, p = 0.01). CAN was associated with HbA1c and age in a multivariate logistic regression analysis but was not associated with IEFND or triglycerides.

INTERPRETATION

One in five patients with DPN have CAN and specific CAN characteristics may help identify patients at risk for developing this severe diabetic complication. Autonomic symptoms were strongly associated with having both DPN and CAN, but too unspecific for diagnosing CAN.

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

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

Detecting and treating the protean manifestations of diabetic autonomic neuropathy

The manifestations of diabetic autonomic neuropathy (DAN) are protean and clinically involve multiple systems, including the cardiovascular system, the gastrointestinal system, the genitourinary system as well as the sweat glands (sudomotor dysfunction) and the gallbladder. In addition, cardiac autonomic neuropathy (CAN) is associated with a correctible inability to appreciate and correct hypoglycaemia. While not a clinical problem, pupillary involvement should be the clue and the catalyst to investigate for other manifestations of DAN. This review outlines a practical approach to detecting and investigating the manifestations of DAN. Of particular importance is early detection of cardiovascular involvement where prompt therapy through glycaemic control can decrease the severity of CAN and decelerate the frequency and severity of retinopathy and nephropathy in addition to decreasing cardiovascular events and mortality. CAN also plays a role in accelerating other diabetic complications such as acute ischaemic stroke, heart failure, medial artery calcinosis, foot ulcers, peripheral artery disease and Charcot joints. Many therapies of DAN are available, which should not only decrease morbidity and mortality from DAN, but also improve the patient's quality of life. However, the therapies available are largely symptomatic.

Evaluation of bladder dysfunction in children and adolescents with type 1 diabetes mellitus by uroflowmetry

OBJECTIVES

Diabetic cystopathy is a condition characterized by decreased bladder sensitivity, increased bladder capacity, decreased bladder contractility and increased residual urine volume. It can also be considered as an early indicator of autonomic dysfunction. In this study, it was aimed to evaluate bladder functions by uroflowmetry in children and adolescents with the diagnosis of type 1 diabetes mellitus.

METHODS

Type 1 diabetes mellitus children and adolescents were applied uroflowmetry and post-void residual urine volumes were evaluated. The physical examination findings of the patients and the laboratory data of diabetes control were obtained from the clinic files.

RESULTS

A total of 51 cases aged 72-216 (155.6 ± 35.4) months were enrolled into the study. Diabetes age of the cases was 66.5 ± 46.2(13-180) months. The last one year average of HbA_1c of the patients was found to be 9.7 ± 1.9%. A total of 9.8% had good, 39.2% moderate and 51% poor metabolic control, respectively. While urodynamic evaluation was normal in 36 (70.6%) of 51 participants, voiding dysfunction was found in 15. There was no statistically significant difference between groups with and without voiding dysfunction in terms of age, gender, duration of diabetes, metabolic control and HbA_1c values.

CONCLUSIONS

It is very important to follow up patients with type 1 diabetes mellitus in terms of autonomic dysfunction. Diabetic bladder clinic, which can be observed independently of diabetes duration and metabolic control, is also included in this status. Urodynamic evaluation will be helpful both in demonstrating bladder dysfunction and in preventing possible complications.

Abdominal and Pelvic Computed Tomography for the Diagnosis of ST-Elevation Myocardial Infarction: The Challenges of Acute Coronary Syndrome in Diabetic Patients

Diabetes mellitus (DM) is a major independent risk factor for cardiovascular disease. Patients who present with the metabolic emergency of diabetic ketoacidosis (DKA) have similar symptoms of diaphoresis, nausea, emesis, and abdominal pain, which can conceal acute coronary syndrome (ACS). We present a unique case where computed tomography (CT) of the abdomen and pelvis with IV contrast played an integral role in diagnosing an acute myocardial infarction in a patient with no typical ischemic symptoms. A 56-year-old female presented to the emergency department with abdominal pain, nausea, and vomiting. She was suspected of having DKA. Aggressive management was started, including weight-based appropriate IV regular insulin. A CT abdomen and pelvis with IV contrast was performed due to persistent abdomen pain. This demonstrated severe hypoattenuation of the posteroinferior aspect of the left ventricular wall. An EKG was immediately performed and was consistent with an inferior STEMI. The patient was taken to the interventional cardiology suite where they found the culprit lesion to be mid-circumflex with 100% stenosis. This case highlights many important lessons in approaching diabetic patients who are presenting with DKA. DM is associated with cardiac autonomic neuropathy (CAN), a condition that greatly influences perceived chest pain. While little is known about this condition, some manifestations include resting tachycardia, exercise intolerance, orthostatic hypotension, and an increased risk of silent myocardial infarction. Critically, providers must maintain a low threshold to assess for cardiac ischemia in diabetic patients and more readily obtain EKGs in triage as well as during the patient's course in the ED to prevent complications from delayed ACS care.

Platelet-to-Lymphocyte Ratio Predicts the Presence of Diabetic Neurogenic Bladder

PURPOSE

Diabetic neurogenic bladder (DNB) has been widely recognized in recent years. It is common in patients with long-term diabetes and may also lead to many severe complications. Although there has been widespread evidence that inflammation is involved in the development of some diabetic complications, there is little evidence that this can also occur in the bladder. In recent years, platelet-to-lymphocyte ratio (PLR) and neutrophil-to-lymphocyte ratio (NLR) have been viewed as potential novel markers of inflammatory responses. This study was designed to evaluate the relationship between the presence of DNB and the PLR and NLR.

PATIENTS AND METHODS

A total of 371 cases of T2DM patients were included in this retrospective study. Patients were divided into two groups, with 115 diabetic subjects diagnosed with diabetic neurogenic bladder and 256 control subjects without DNB. The independent predictors of DNB were analyzed using logistic regression.

RESULTS

Compared with patients without DNB, the mean PLR and NLR were significantly higher in those with DNB (p < 0.001). Based on the logistic regression, PLR was found to be an independent risk factor for DNB (odds ratio [OR]: 1.408, 95% confidence interval [CI]: 1.248-1.617). From the receiver operating characteristic (ROC) curve, using PLR as indicative of DNB was expected to be 101.1949, and it generated a sensitivity and specificity value of 89.6% and 23.4%, respectively. The area under the curve (AUC) was also found to be 0.899 (95% CI: 0.865-0.932).

CONCLUSION

In our study, PLR and NLR were significantly higher for patients with DNB. The PLR was found to be a risk factor in the presence of DNB after correcting for possible confounding factors. Considering the severe complications associated with DNB, patients with elevated PLR should be seriously cared for in clinics.

Diabetic autonomic neuropathy: a clinical update

Diabetic autonomic neuropathy is an under-recognised complication of diabetes and the prediabetic state. A wide range of manifestations can be seen due to involvement of cardiovascular, gastrointestinal, genitourinary, sudomotor and neuroendocrine systems. Cardiac autonomic neuropathy is the most dreaded complication carrying significant mortality and morbidity. Early detection and control of diabetes and other cardiovascular risk factors is the key to treat and prevent progression of autonomic neuropathy. Recently, a new entity of treatment-induced neuropathy (TIND) of diabetes mellitus causing autonomic neuropathy is being increasingly recognised.

Using System Identification to Construct an Inherent Model of Pupillary Light Reflex to Explore Diabetic Neuropathy

This study proposed a pupillary light reflex (PLR) inherent model based on the system identification method to demonstrate the dynamic physiological mechanism of the PLR, in which pupillary constriction and dilation are controlled by the sympathetic and parasympathetic nervous system. This model was constructed and verified by comparing the simulated and predicted PLR response with that of healthy participants. The least root-mean-square error (RMSE) of simulated PLR response was less than 0.7% when stimulus duration was under 3 ms. The RMSE of predicted PLR response increased by approximately 6.76%/s from the stimulus duration of 1 ms to 3 s, when the model directly used the parameters extracted from the PLR at the stimulus duration of 10 ms. When model parameters were derived from the regression by the measured PLR response, the RMSE kept under 8.5%. The model was applied to explore the PLR abnormalities of the people with Diabetic Mellitus (DM) by extracting the model parameters from 42 people with DM and comparing these parameters with those of 42 healthy participants. The parameter in the first-order term of the elastic force of the participants with DM was significantly lower than that of the healthy participants (p < 0.05). The sympathetic force and sympathetic action delay of the participants with DM were significantly larger (p < 0.05) and longer (p < 0.0001) than that of the healthy ones, respectively. The reason might be that the sympathetic nervous system, which controls the dilator muscle, degenerated in diabetic patients.

Evaluation of the Degree of Agreement of Four Methods for Diagnosing Diabetic Autonomic Neuropathy

Background: There are many methods to diagnose diabetic autonomic neuropathy (DAN); however, often, the various methods do not provide consistent results. Even the two methods recommended by the American Diabetes Association (ADA) guidelines, Ewing's test and heart rate variability (HRV), sometimes give conflicting results. The purpose of this study was to evaluate the degree of agreement of the results of the Composite Autonomic Symptom Score 31 (COMPASS-31), skin sympathetic reaction (SSR) test, Ewing's test, and HRV in diagnosing DAN.

Methods: Patients with type 2 diabetes were recruited and each received the COMPASS-31, SSR, Ewing's test, and HRV for the diagnosis of DAN. Patients were categorized as DAN(+) and DAN(–) by each of the tests. Kappa consistency tests were used to evaluate the agreement of diagnosing DAN between any two methods. Spearman's correlation test was used to evaluate the correlations of the severity of DAN between any two methods. Receiver operating characteristic (ROC) analyses were used to evaluate the diagnostic value and the cutoff value of each method.

Results: A total of 126 type 2 diabetic patients were included in the study. The percentages of DAN(+) results by HRV, Ewing's test, COMPASS-31, and SSR were 61, 40, 35, and 33%, respectively. COMPASS-31 and Ewing's test had the best agreement for diagnosing DAN (κ = 0.512, p < 0.001). COMPASS-31 and Ewing's test also had the best correlation with respect to the severity of DAN (r = 0.587, p < 0.001). Ewing's test and COMPASS-31 had relatively good diagnostic values (AUC = 0.703 and 0.630, respectively) in the ROC analyses.

Conclusions: COMPASS-31 and Ewing's test exhibit good diagnostic consistency and severity correlation for the diagnosis of DAN. Either test is suitable for the diagnosis of DAN and treatment follow-up.

Assessing heart rate variability in type 1 diabetes mellitus-Psychosocial stress a possible confounder

BACKGROUND

Autonomic neuropathy (AN) commonly arises as a long-term complication in diabetes mellitus and can be diagnosed from heart rate variability (HRV), calculated from electrocardiogram recordings. Psychosocial stress also affects HRV and could be one of several confounders for cardiac AN. The present work investigated the impact of psychosocial stress on HRV in individuals with type 1 diabetes mellitus (T1DM) and assessed the use of salivary cortisol as a biomarker for psychosocial stress in this context.

METHODS

A total of 167 individuals 6-60 years old (113 with T1DM and 54 healthy controls) underwent 24-hr ECG recordings with HRV analysis. Salivary cortisol was sampled thrice during the registration day. Perceived psychosocial stress along with other factors of possible importance for the interpretation of HRV was documented in a diary.

RESULTS

Heart rate variability (high-frequency power during sleep) was reduced (p < .05) with older age, longer diabetes duration, higher mean glucose levels, physical inactivity, and perceived psychosocial stress. Salivary cortisol levels in the evening were increased (p < .05) in women in ovulation phase, in individuals with preceding hypoglycemia or with hyperglycemia. The amplitude of salivary cortisol was reduced (p < .05) with the presence of perceived psychosocial stress, but only in adult healthy controls, not in individuals with diabetes.

CONCLUSION

Psychosocial stress might be a confounder for reduced HRV when diagnosing cardiac AN in T1DM. Salivary cortisol is, however, not a useful biomarker for psychosocial stress in diabetes since the physiological stress of both hypoglycemia and hyperglycemia seems to overrule the effect of psychosocial stress on cortisol.

Association of pupil responses with severity of erectile dysfunction in diabetes mellitus

Purpose:

To investigate the relation between erectile dysfunction (ED) severity and pupillary functions in patients with diabetes mellitus (DM).

Methods:

This prospective and observational study included 90 patients with type 2 DM and ED. Patients divided into three subgroups according to severity of ED: (i) Mild ED, (ii) Moderate ED and (iii) Severe ED groups. Thirty age-matched healthy subjects formed the control group. Main outcome measures were pupil diameter and average speed of pupil dilation. Static and dynamic pupillometry analysis was performed using the Sirius Topographer (CSO, Firenze, Italy).

Results:

Mean pupil diameter during static and dynamic pupillometry analysis were significantly greater in the control group than in the all study groups (P < 0.05). Mean pupil diameter in static pupillometry analysis was significantly different in each study group and pupil was more miotic in the Severe ED group than in the both Moderate and Mild ED groups (P < 0.05 for each). Dynamic pupillometry analysis revealed that mean pupil diameter and mean average dilation speed were significantly different in each study group throughout measurement period and the highest speed was observed in the Mild ED group and the lowest speed was observed in the severe ED group (P < 0.005 for each).

Conclusion:

Our study results suggest that abnormal pupil functions due to diabetic autonomic neuropathy may indicate the associated ED in patients with DM.

Postprandial Blood Pressure Decrease in Patients with Type 2 Diabetes and Mild or Severe Cardiac Autonomic Dysfunction

Background Few reports have evaluated the relationship between changes in postprandial blood pressure and the severity of autonomic dysfunction in patients with type 2 diabetes. This was a cross-sectional study designed to investigate postprandial blood pressure changes in individuals without type 2 diabetes and patients with type 2 diabetes and mild or severe cardiac autonomic dysfunction. Methods Forty patients with type 2 diabetes mellitus and 20 individuals without type 2 diabetes participated in this study. Fifty-two participants underwent a meal tolerance test. Blood pressure (brachial systolic blood pressure (bSBP) and central systolic blood pressure (cSBP)), electrocardiogram recordings, and blood samples were assessed before and after meal ingestion. Patients with diabetes were divided into two groups based on their coefficient of variation of R⁻R intervals (CVRR): a normal or mildly dysfunctional group (mild group, CVRR ≥ 2%; n = 20) and a severely dysfunctional group (severe group, CVRR < 2%; n = 15). Results In the control group, bSBP and cSBP did not significantly change after meal ingestion, whereas both decreased significantly at 60 min after meal ingestion in the mild and severe groups. While blood pressure recovered at 120 min after meal ingestion in the mild group, a significant decrease in blood pressure persisted at 120 min after meal ingestion in the severe group. Conclusions Based on these results, adequate clinical attention should be paid to the risk of serious events related to postprandial decreases in blood pressure, particularly in patients with diabetes and severe cardiac autonomic dysfunction.

Droxidopa for Hypotension of Different Etiologies: Two Case Reports

Orthostatic hypotension is defined as a decrease in systolic blood pressure of at least 20 mmHg or a decrease in diastolic blood pressure of at least 10 mmHg (or both), within three minutes of moving from a supine to an upright or standing position. Droxidopa is a synthetic amino acid analog that is directly metabolized to norepinephrine by dopa-decarboxylase, subsequently providing alpha and beta-agonist effects to increase blood pressure. It is indicated in the treatment of neurogenic orthostatic hypotension caused by primary autonomic failure that is associated with Parkinson disease, multi-system atrophy, pure autonomic failure, dopamine beta-hydroxylase deficiency, and/or non-diabetic autonomic neuropathy. In addition, it has been studied in other disease states, such as diabetic autonomic neuropathy-associated orthostatic hypotension and supine hypotension. We report on two cases of off-label droxidopa use. The first case was for diabetic autonomic neuropathy-associated orthostatic hypotension, and the second case was for hypotension due to autonomic dysfunction associated with rheumatoid arthritis. Although the outcomes differed in each case, this article contributes to the literature demonstrating that droxidopa may have varying effects in treating orthostatic hypotension of non-neurogenic etiology.

The association between cardiac autonomic neuropathy and diabetes control

Introduction: Cardiac autonomic neuropathy (CAN) is one of major complications of diabetes mellitus (DM) that increases the risk of cardiovascular disorders, abnormal ventricular depolarization with poor prognosis as well as increased mortality and morbidity. Indeed, CAN has close relation with blood glucose level in diabetic patients. We investigated the relation of CAN with diabetes control. Materials and methods: Totally, 115 diabetic patients (mean age 50.87±13.90 years old; 78 females) underwent study. All patients had DM and cardiac sinus rhythm. Nobody had sickness affecting cardiac rhythm and blood pressure. In addition, they did not take drugs that had effect on blood pressure, cardiac rhythm, and QT interval. Forty-six patients had tight and 69 patients had uncontrolled DM according to American Diabetes Association (ADA) criteria. The CAN was assessed based on heart rate variation during physical examination (at rest tachycardia and orthostatic hypotension) and standard Ewing's tests (deep-breathing and laying-to-standing tests) with bedside continuous ECG recording. The P-value <0.05 is considered significant. Results: Seventy-five patients (65.2%) had CAN. In patients with CAN, 13.9% were symptomatic and 51.3% were asymptomatic. Resting tachycardia and hypotension were found in 5.2%, 8.7% of patients, respectively. Abnormal deep-breathing and laying-to-standing tests were found in 73% and 71.3% of asymptomatic patients, respectively. CAN was more prevalence at uncontrolled DM (67.3% vs 63.7%) but the difference was not significant. The prevalence of CAN had direct association with duration of DM in both tight and uncontrolled groups (P<0.05). The mean of age, sex, and type of treatment had no association with CAN prevalence. Conclusion: The prevalence of CAN, especially asymptomatic type, was high. Its prevalence was increased with prolonged duration of DM. But we did not find any relationship between CAN and glycemic control level.

Present Insights on Cardiomyopathy in Diabetic Patients

The pathogenesis of diabetic cardiomyopathy (DCM) is partially understood and is likely to be multifactorial, involving metabolic disturbances, hypertension and cardiovascular autonomic neuropathy (CAN). Therefore, an important need remains to further delineate the basic mechanisms of diabetic cardiomyopathy and to apply them to daily clinical practice. We attempt to detail some of these underlying mechanisms, focusing in the clinical features and management. The novelty of this review is the role of CAN and reduction of blood pressure descent during sleep in the development of DCM. Evidence has suggested that CAN might precede left ventricular hypertrophy and diastolic dysfunction in normotensive patients with type 2 diabetes, serving as an early marker for the evaluation of preclinical cardiac abnormalities. Additionally, a prospective study demonstrated that an elevation of nocturnal systolic blood pressure and a loss of nocturnal blood pressure fall might precede the onset of abnormal albuminuria and cardiovascular events in hypertensive normoalbuminuric patients with type 2 diabetes. Therefore, existing microalbuminuria could imply the presence of myocardium abnormalities. Considering that DCM could be asymptomatic for a long period and progress to irreversible cardiac damage, early recognition and treatment of the preclinical cardiac abnormalities are essential to avoid severe cardiovascular outcomes. In this sense, we recommend that all type 2 diabetic patients, especially those with microalbuminuria, should be regularly submitted to CAN tests, Ambulatory Blood Pressure Monitoring and echocardiography, and treated for any abnormalities in these tests in the attempt of reducing cardiovascular morbidity and mortality.

Heart rate turbulence in patients with poorly controlled diabetes mellitus type 2

INTRODUCTION

Cardiac autonomic neuropathy (CAN) causes substantial morbidity and increased mortality in patients with diabetes mellitus (DM). Besides heart rate variability (HRV), heart rate turbulence (HRT) is an important method of assessment of cardiac autonomic regulation. The aim of the study was to assess the correlation between HRT and diabetic control.

MATERIAL AND METHODS

Fifty-nine patients met the inclusion criteria - 38 males and 21 females, age 64.4 ±7.6. The patients included had inadequately controlled DM type 2 defined as glycated haemoglobin (HbA1c) > 9% (mean 11.8 ±2.7%). In all patients, intensive insulin treatment had been applied for 6 months. After 6 months, HbA1c was measured. ECG Holter monitoring was performed before and after insulin treatment to evaluate the time domain HRV and HRT parameters (turbulence onset (TO) and turbulence slope (TS)).

RESULTS

After 6 months of intensive insulin treatment, HbA1c concentrations ranged from 6.3% (45 mmol/mol) to 11.2% (99 mmol/mol) - mean 8.5 ±3.8% (69 ±18 mmol/mol). Significant improvement of TO, TS and SDNN was observed. The TO and TS significantly correlated with HbA1c (r = 0.35, p = 0.006 and r = -0.31, p = 0.02 respectively). Among analyzed HRV time domain parameters such as SDNN, rMSSD and pNN50, only SDNN correlated with HbA1c (r = -0.41, p = 0.001). It was further concluded that intensive insulin therapy led to better glycemic control, resulting in improvement of HRT.

CONCLUSIONS

Heart rate turbulence may be useful in monitoring changes of the autonomic nervous system functions in patients with DM, similarly to HRV parameters.

Association of diabetic autonomic neuropathy with red blood cell aldose reductase activity

OBJECTIVE

Activation of polyol pathway based on increased activity of aldose reductase (AR) has been implicated in the development of diabetic complications including diabetic autonomic neuropathy (DAN). The relationship between DAN and hyperglycemia-induced activation of polyol pathway is still uncertain. In the present study, we investigate the association between aldose reductase activity and diabetic autonomic neuropathy by measuring AR level in red blood cells (RBC).

METHOD

In this study, 145 subjects with diabetes with or without DAN and 32 subjects without diabetes have been included. All subjects have been investigated for autonomic function tests and RBC aldose reductase activity. DAN was defined if results of any 2 of the tests of parasympathetic function were abnormal. RBC aldose reductase level was determined spectrophotometrically and expressed as unit/g of hemoglobin. The values were expressed as mean ± standard deviation, and ANOVA test has been applied for comparison between groups.

RESULTS

RBC aldose reductase activity was found to be significantly higher in people with diabetes with autonomic neuropathy in comparison to people with diabetes without autonomic neuropathy and healthy individuals without diabetes. Aldose reductase (AR) level ranges from 0.8 units/g Hb to 14.2 units/g Hb. The mean AR level was 8.6±2.95 units in subjects of DM with autonomic neuropathy, while mean AR level was 4.1±1.78 units and 2.0±0.89 units in people with diabetes without neuropathy and normal healthy individuals, respectively (p<0.001).

CONCLUSIONS

High aldose reductase activity is associated with the presence of autonomic neuropathy in subjects of type 2 DM.

Cardiovascular autonomic neuropathy contributes to sleep apnea in young and lean type 1 diabetes mellitus patients

Knowledge about association between sleep apnea and cardiovascular autonomic neuropathy (CAN) in type 1 diabetes mellitus (T1DM) might give some insight into the pathogenesis of this condition in these patients. In obese patients, excessive central adiposity, including a large neck circumference, can contribute to obstructive sleep apnea (OSA). Its presence in non-obese patients, however, indicates that it could be correlated with autonomic neuropathy. The aim of this study was to compare the prevalence of OSA in young and lean T1DM patients with and without CAN. We studied 20 adult, non-obese, T1DM patients who were divided into two groups according to the results of the cardiovascular autonomic reflex tests (CARTs). These two groups (9 with CAN and 11 without CAN) were compared to a control group of 22 healthy individuals, who were matched by age and BMI. A polysomnography was performed and sleep was analyzed. The CAN+ group had a significantly higher prevalence of sleep apnea compared to the other groups (67% CAN+; 23% CAN-; 4.5% controls: CAN+ vs. Control; p = 0.006 and CAN+ vs. CAN-; p = 0.02). The CAN- group had higher sleep efficiency compared to the CAN+ group, demonstrating impaired sleep architecture in diabetics with this chronic complication. In conclusion, OSA may be related to the presence of CAN in young and lean T1DM patients. It could contribute to worse the prognosis and reducing the quality of life of these patients without specific treatment of these conditions.

Autonomic neuropathy in diabetes mellitus

Diabetic autonomic neuropathy (DAN) is a serious and common complication of diabetes, often overlooked and misdiagnosed. It is a systemic-wide disorder that may be asymptomatic in the early stages. The most studied and clinically important form of DAN is cardiovascular autonomic neuropathy defined as the impairment of autonomic control of the cardiovascular system in patients with diabetes after exclusion of other causes. The reported prevalence of DAN varies widely depending on inconsistent definition, different diagnostic method, different patient cohorts studied. The pathogenesis is still unclear and probably multifactorial. Once DAN becomes clinically evident, no form of therapy has been identified, which can effectively stop or reverse it. Prevention strategies are based on strict glycemic control with intensive insulin treatment, multifactorial intervention, and lifestyle modification including control of hypertension, dyslipidemia, stop smoking, weight loss, and adequate physical exercise. The present review summarizes the latest knowledge regarding clinical presentation, epidemiology, pathogenesis, and management of DAN, with some mention to childhood and adolescent population.

Animal models of peripheral neuropathies

Peripheral neuropathies are common neurological diseases, and various animal models have been developed to study disease pathogenesis and test potential therapeutic drugs. Three commonly studied disease models with huge public health impact are diabetic peripheral neuropathy, chemotherapy-induced peripheral neuropathy, and human immunodeficiency virus-associated sensory neuropathies. A common theme in these animal models is the comprehensive use of pathological, electrophysiological, and behavioral outcome measures that mimic the human disease. In recent years, the focus has shifted to the use of outcome measures that are also available in clinical use and can be done in a blinded and quantitative manner. One such evaluation tool is the evaluation of epidermal innervation with a simple skin biopsy. Future clinical trials will be needed to validate the translational usefulness of this outcome measure and validation against accepted outcome measures that rely on clinical symptoms or examination findings in patients.

Cardiovascular autonomic neuropathy in diabetes: clinical impact, assessment, diagnosis, and management

The Cardiovascular Autonomic Neuropathy (CAN) Subcommittee of the Toronto Consensus Panel on Diabetic Neuropathy worked to update CAN guidelines, with regard to epidemiology, clinical impact, diagnosis, usefulness of CAN testing, and management. CAN is the impairment of cardiovascular autonomic control in the setting of diabetes after exclusion of other causes. The prevalence of confirmed CAN is around 20%, and increases up to 65% with age and diabetes duration. Established risk factors for CAN are glycaemic control in type 1 and a combination of hypertension, dyslipidaemia, obesity, and glycaemic control in type 2 diabetes. CAN is a risk marker of mortality and cardiovascular morbidity, and possibly a progression promoter of diabetic nephropathy. Criteria for CAN diagnosis and staging are: (1) one abnormal cardiovagal test result identifies possible or early CAN; (2) at least two abnormal cardiovagal test results are required for definite or confirmed CAN; and (3) the presence of orthostatic hypotension in addition to abnormal heart rate test results identifies severe or advanced CAN. Progressive stages of CAN are associated with increasingly worse prognosis. CAN assessment is relevant in clinical practice for (1) diagnosis of CAN clinical forms, (2) detection and tailored treatment of CAN clinical correlates (e.g. tachycardia, orthostatic hypotension, non-dipping, QT interval prolongation), (3) risk stratification for diabetic complications and cardiovascular morbidity and mortality, and (4) modulation of targets of diabetes therapy. Evidence on the cost-effectiveness of CAN testing is lacking. Apart from the preventive role of intensive glycaemic control in type 1 diabetes, recommendations cannot be made for most therapeutic approaches to CAN.

Anorexia nervosa or not? A case presentation

The authors of this article present a case of diabetic gastroparesis, initially diagnosed as anorexia nervosa. They compare the symptoms and signs of diabetic gastroparesis with the diagnostic criteria for anorexia nervosa and discuss treatment with domperidone.