Neurovascular function and sudorimetry in health and disease

Recent advances in nonenzymatic electrochemical biosensors for sports biomarkers: focusing on antibodies, aptamers and molecularly imprinted polymers

Nonenzymatic electrochemical biosensors, renowned for their high sensitivity, multi-target analysis capabilities, and miniaturized integration, align well with the requirements of non-invasive, multi-index integrated, continuous monitoring, and user-friendly wearable biosensors in sports science. In the past three years, novel strategies targeting specific responses to sports biomarkers have opened new avenues for applications in sports science. However, these advancements also pose challenges in achieving adequate sensitivity and specificity for online analysis of complex sweat bio-samples. Our article focuses on three key nonenzymatic electrochemical biosensing strategies: antigen-antibody reactions, nucleic acid aptamer recognition, and molecular imprinting capture. We delve into strategies to enhance specificity and sensitivity in the application of biosensors in sports science, including shortening signal transduction paths through built-in signal probes, increasing reaction sites through increased surface area and the introduction of nanostructures, multi-target analyses, and microfluidic techniques.

Parasympathetic and Sympathetic Monitoring Identifies Earliest Signs of Autonomic Neuropathy

The progression of autonomic dysfunction from peripheral autonomic neuropathy (PAN) to cardiovascular autonomic neuropathy, including diabetic autonomic neuropathy and advanced autonomic dysfunction, increases morbidity and mortality risks. PAN is the earliest stage of autonomic neuropathy. It typically involves small fiber disorder and often is an early component. Small fiber disorder (SFD) is an inflammation of the C-nerve fibers. Currently, the most universally utilized diagnostic test for SFD as an indicator of PAN is galvanic skin response (GSR), as it is less invasive than skin biopsy. It is important to correlate a patient's symptoms with several autonomic diagnostic tests so as not to treat patients with normal findings unnecessarily. At a large suburban northeastern United States (Sicklerville, NJ) autonomic clinic, 340 consecutive patients were tested with parasympathetic and sympathetic (P&S) monitoring (P&S Monitor 4.0; Physio PS, Inc., Atlanta, GA, USA) with cardiorespiratory analyses, and TMFlow (Omron Corp., Hoffman Estates, Chicago, IL, USA) with LD Technology sudomotor test (SweatC™). This is a prospective, nonrandomized, observational, population study. All patients were less than 60 y/o and were consecutively tested, analyzed and followed from February 2018 through May 2020. P&S Monitoring is based on cardiorespiratory analyses and SweatC™ sudomotor testing is based on GSR. Overall, regardless of the stage of autonomic neuropathy, SweatC™ and P&S Monitoring are in concordance for 306/340 (90.0%) of patients from this cohort. The result is an 89.4% negative predictive value of any P&S disorder if the sudomotor GSR test is negative and a positive predictive value of 90.4% if the sudomotor testing is positive. In detecting early stages of autonomic neuropathy, P&S Monitoring was equivalent to sudomotor testing with high sensitivity and specificity and high negative and positive predictive values. Therefore, either testing modality may be used to risk stratify patients with suspected autonomic dysfunction, including the earliest stages of PAN and SFD. Moreover, when these testing modalities were normal, their high negative predictive values aid in excluding an underlying autonomic nervous system dysfunction.

Cardiac and Sudomotor Autonomic Function in Subjects with Psoriasis With and Without Metabolic Syndrome

Purpose: Studies have shown that subjects with psoriasis (PsO) are associated with an increased risk of developing metabolic syndrome (MetS), diabetes, and cardiovascular disease. In addition, MetS and diabetes are associated with autonomic dysfunction (AD). The aim of this study was to investigate cardiac and sudomotor autonomic function in subjects with PsO and without diabetes. Methods: A cross-sectional study was performed in 20 subjects with PsO, compared with age- and sex-matched 21 healthy controls, and 20 subjects with MetS. Subjects underwent skin evaluation by dermatologist, glycated hemoglobin (HbA1c), insulin, glucose, and lipid levels, sudomotor function testing with Sudoscan^™ device (Impeto Medical, Paris, France), and cardiac autonomic function testing with ANSAR device (ANX 3.0; ANSAR Group, Inc., Philadelphia, PA). Quality of Life (QOL) and peripheral neurologic function were also assessed. Results: Participants with PsO were significantly more obese, had higher levels of fasting insulin and triglycerides, and were more insulin resistant when compared to controls. Subjects with PsO showed significantly worse cardiac autonomic function when compared to control and MetS groups. Sudomotor function and QOL scores were similar between the groups. Subgroup analysis of PsO subjects without MetS criteria (n = 15) showed persistent significantly deteriorated cardiac autonomic function when compared to the other two groups. Conclusion: This study suggests an association between PsO and cardiac AD, independent of the presence of overt dysglycemia and MetS. Additional larger studies are needed to clarify the significance of these findings and the relationship between PsO, AD, and metabolic disease.

Diabetes Distal Peripheral Neuropathy: Subtypes and Diagnostic and Screening Technologies

Diabetes distal symmetrical peripheral neuropathy (DSPN) is the most prevalent form of neuropathy in industrialized countries, substantially increasing risk for morbidity and pre-mature mortality. DSPN may manifest with small-fiber disease, large-fiber disease, or a combination of both. This review summarizes: (1) DSPN subtypes (small- and large-fiber disease) with attention to clinical signs and patient symptoms; and (2) technological diagnosis and screening for large- and small-fiber disease with inclusion of a comprehensive literature review of published studies from 2015-present (N = 66). Review findings, informed by the most up-to-date research, advance critical understanding of DSPN large- and small-fiber screening technologies, including those designed for point-of-care use in primary care and endocrinology practices.

Baseline extended zone retinal vascular calibres associate with sensory nerve abnormalities in adolescents with type 1 diabetes: A prospective longitudinal study

OBJECTIVE

The relationship between retinal vascular calibres (RVCs) and diabetic neuropathy is unclear. We investigated associations between RVCs and sensory nerve abnormality in adolescents with type 1 diabetes.

RESEARCH DESIGN AND METHODS

In a prospective longitudinal study of 889 adolescents with type 1 diabetes with baseline mean (±SD) age 14.1 ± 1.5 years and HbA_1c IFCC 69.4 ± 14.1 mmol/mol (8.6 ± 1.3%), RVCs were assessed from baseline retinal photographs: 'central zone' calibres, summarized as central retinal arteriolar (CRAE) and venular equivalents (CRVE) and 'extended zone' calibres: mean width of arterioles (MWa) and venules (MWv). Sensory nerve abnormality was defined as at least one abnormal sensory quantitative testing from two thermal and two vibration threshold tests measured at foot every 1-2 years. Associations between baseline RVC and sensory nerve function were examined using generalized estimating equations and cumulative risk by Cox regression analyses.

RESULTS

During a median study follow-up of 6.2 [IQR 3.7-10.4] years, sensory nerve abnormality was found in 27% of adolescents. Narrower extended zone calibre quartiles but not CRAE or CRVE quartiles were independently associated with sensory nerve abnormality: MWa (Q1 vs. Q2-4: OR 1.35 (95% CI 1.02, 1.61) and MWv (Q1 vs. Q2-4: 1.31 (1.03, 1.7)), after adjusting for HbA_1c , duration and blood pressure. Similarly, in Cox regression, the narrowest quartiles were associated with sensory nerve abnormality: MWa hazard ratio (HR) 1.5 (1.3, 1.8) and MWv 1.6 (1.4, 1.9).

CONCLUSIONS

Narrower extended zone retinal calibres were associated with sensory nerve abnormality in adolescents with type 1 diabetes and may present useful biomarkers to understand the pathophysiology of neuropathy.

Is sudoscan a reliable tool in detecting small fiber neuropathy in Parkinson's disease patients?

Aim: Previous studies have revealed uncertainties concerning the utility of sudoscan in identifying small fiber neuropathy in Parkinson's disease (PD). Patients & methods: We searched for a significant reduction of electrochemical skin conductance (ESC) in 67 PD patients versus 66 controls with similar characteristics. We conducted analysis of the subgroups of PD patients without diabetes using sudoscan technology. Results: There is no discrimination between patients and controls relative to feet ESC, the modified Hoehn and Yahr Scale and/or Unified Parkinson's Disease Rating Scale. ESC in patients did not differ significantly according to the Unified Parkinson's Disease Rating Scale score. The oldest PD patients with cardiovascular risk factors have more marked small fibers dysfunction. Conclusion: The sudoscan procedure did not show advantage in the diagnosis of small fiber neuropathy. Its diagnostic value increases in some subgroups of patients with cardiovascular co-morbidity.

Variability of electrochemical skin conductance for screening diabetes mellitus

Electrochemical skin conductance (ESC) has been suggested as a noninvasive diabetic screening tool. We examined the relevance of ESC method for screening type 2 diabetes. A meal tolerance test (MTT) was conducted for 40 diabetic and 42 control subjects stratified by age, sex and body mass index (BMI). The glucose levels and ESC were measured before the MTT and every 30 min after meal intake up to 120 min. There was no correlation between the blood glucose level and ESC (r = 0.249) or ESC variability (ESCV) (r = - 0.173). ESC (ESCV) was higher (lower) in diabetic patients than in normal control (p = 0.02 for ESC and p = 0.06 for ESCV). Receiver operating characteristic analysis showed that the area under the curve (AUC) values of the ESC and ESCV were 0.654 and 0.691, respectively. The novel variable, ESCV, showed 5.7% higher AUC than ESC. Contrary to some previous reports, ESC values in diabetic patients was higher than in age, sex and BMI matched control group. In our study, ESC or ESCV showed a marginal accuracy to be used as a screening tool for diabetes mellitus.

A cardiac risk score based on sudomotor function to evaluate cardiovascular autonomic neuropathy in asymptomatic Chinese patients with diabetes mellitus

Backgrounds

Cardiac autonomic neuropathy is a common but always overlooked. More convenient diagnostic methods are needed.

Hypothesis

Cardiac autonomic neuropathy risk score evaluated by SUDOSCAN has a fine diagnostic efficacy detecting cardiac autonomic neuropathy.

Methods

This is a cross-sectional study among patients with diabetes mellitus. Subjects undertook SUDOSCAN tests and cardiac autonomic reflex tests, including heart rate variability due to Valsalva maneuver, heart rate response due to deep breathing and heart rate response due to standing up. Presenting 2 abnormal results was defined as cardiac autonomic neuropathy.

Results

Subjects with cardiac autonomic neuropathy has significantly higher cardiac autonomic neuropathy risk score (32.88±1.60 vs 27.64±1.24,P = 0.010). Cardiac autonomic neuropathy risk score was correlated significantly with the heart rate response due to deep breathing(P = 0.004). Multiple regression analysis including significant variables showed an independent association of cardiac autonomic neuropathy risk score and heart rate response due to deep breathing (P = 0.031) and age (P = 0.000). In receiver operating characteristic curve analysis evaluating the relationship between cardiac autonomic neuropathy risk score and cardiac autonomic neuropathy, The cut-off value was 20.5, with the sensitivity of 90.48%, the specificity of 29.5%, and the positive predictive value of 46.9%. In two-step diagnostic methods, Setting 20.5 as the cut-off value of cardiac autonomic neuropathy risk score and abnormal heart rate response due to standing up as the second diagnostic step’s positive result, and setting 16.5 as the cut-off value of cardiac autonomic neuropathy risk score and abnormal heart rate response due to deep breathing as the second diagnostic step’s positive result, both achieved good diagnostic efficacy.

Conclusion

Cardiac autonomic neuropathy risk score evaluated by SUDOSCAN is a good screening test for cardiac autonomic neuropathy. The two-step diagnostic methods could be considered as surrogate diagnostic methods.

Diabetic Microvascular Disease: An Endocrine Society Scientific Statement

Both type 1 and type 2 diabetes adversely affect the microvasculature in multiple organs. Our understanding of the genesis of this injury and of potential interventions to prevent, limit, or reverse injury/dysfunction is continuously evolving. This statement reviews biochemical/cellular pathways involved in facilitating and abrogating microvascular injury. The statement summarizes the types of injury/dysfunction that occur in the three classical diabetes microvascular target tissues, the eye, the kidney, and the peripheral nervous system; the statement also reviews information on the effects of diabetes and insulin resistance on the microvasculature of skin, brain, adipose tissue, and cardiac and skeletal muscle. Despite extensive and intensive research, it is disappointing that microvascular complications of diabetes continue to compromise the quantity and quality of life for patients with diabetes. Hopefully, by understanding and building on current research findings, we will discover new approaches for prevention and treatment that will be effective for future generations.

Schwann cell interactions with axons and microvessels in diabetic neuropathy

The prevalence of diabetes worldwide is at pandemic levels, with the number of patients increasing by 5% annually. The most common complication of diabetes is peripheral neuropathy, which has a prevalence as high as 50% and is characterized by damage to neurons, Schwann cells and blood vessels within the nerve. The pathogenic mechanisms of diabetic neuropathy remain poorly understood, impeding the development of targeted therapies to treat nerve degeneration and its most disruptive consequences of sensory loss and neuropathic pain. Involvement of Schwann cells has long been proposed, and new research techniques are beginning to unravel a complex interplay between these cells, axons and microvessels that is compromised during the development of diabetic neuropathy. In this Review, we discuss the evolving concept of Schwannopathy as an integral factor in the pathogenesis of diabetic neuropathy, and how disruption of the interactions between Schwann cells, axons and microvessels contribute to the disease.

Predictors of autonomic neuropathy in rheumatoid arthritis

OBJECTIVE

Autonomic dysfunction occurs in rheumatoid arthritis (RA). However, the association between the autonomic dysfunction and inflammation has not been investigated in RA. We investigated the relationship between inflammation and ANS function in RA.

METHODS

In this cross-sectional study, 25 RA patients and 25 age and sex-matched healthy controls were recruited. Autonomic function assessed by five cardiovascular reflex tests according to Ewing. Parasympathetic dysfunction established by applying three tests: heart rate response to deep breath (HRD) and standing (HRS) and Valsalva tests. Sympathetic dysfunction examined by applying two tests: BP response to standing and handgrip test. Peripheral sympathetic autonomic function assessed by Sudoscan through measurement of electrochemical skin conductance of hands and feet. Sudoscan investigates the sweat gland activity and used as a surrogate to study the damage of sympathetic sudomotor nerves in neuropathy. It is an indirect assessment tool of sudomotor function. Disease-specific and inflammatory measures (DAS 28, ESR, CRP, TNF-α, IL-6 and IL-1) were determined.

RESULTS

RA patients had significantly impaired HRD, HRS, BP response to hand grip and sudomotor function as compared to healthy controls. Pro-inflammatory cytokines were significantly higher in RA as compared to healthy controls (p<0.05). DAS 28 significantly correlated with HRD in RA. ESR significantly correlated with HRD and HRS. TNF-α significantly correlated with HRD, HRS, BP response to standing and sudomotor function. Significant correlation was found between IL-6 and HRS. Seropositive patients had more pronounced CAN and sudomotor dysfunction.

CONCLUSION

Autonomic dysfunction in RA is related to disease activity, seropositivity and pro-inflammatory cytokines.

Normative Values for Electrochemical Skin Conductances and Impact of Ethnicity on Quantitative Assessment of Sudomotor Function

BACKGROUND

Sudomotor dysfunction is one of the earliest pathophysiologic abnormalities in diabetes. Sudoscan™ (Impeto Medical, Paris, France) was developed as a noninvasive, rapid, and quantitative assessment of sudomotor function and has been shown to be sensitive in the detection of neuropathy. This global collaborative analysis aimed to establish reference values in healthy subjects of different ethnic groups, age, and gender, to define factors potentially affecting results, and to provide standardization of the methodology.

MATERIALS AND METHODS

Data from 1,350 generally healthy study participants who underwent sudomotor function testing were collected and analyzed. The relationship between age, height, weight, gender, glycemic and lipid profiles, ethnicity, and hand and foot electrochemical skin conductance (ESC) was assessed among subgroups of participants.

RESULTS

Lower mean hands and feet ESC values were observed in African American, Indian, and Chinese subjects (P < 0.0001). No participant discomfort or safety concern was reported in 1,376 tests. No significant difference in ESC was observed between women and men at the hands (75 [57-87] vs. 76 [56-89] μS; P = 0.35) or feet (83.5 [71-90] vs. 82.5 [70-91] μS; P = 0.12). The coefficient of correlation between right and left side ESC was r = 0.96, P < 0.0001 for hands and r = 0.97, P < 0.0001 for feet. A significant but weak correlation was observed between ESC and age: for hands, r = -0.17, P < 0.0001; for feet, r = -0.19, P < 0.0001.

CONCLUSIONS

A normative reference range was established in whites showing that there was no effect of sex or body mass index and a slight decrease in ESC with age. Ethnicity influenced ESC scores, but additional studies are necessary to validate this effect and determine its mechanism and impact on nerve function.

Bariatric Surgery Restores Cardiac and Sudomotor Autonomic C-Fiber Dysfunction towards Normal in Obese Subjects with Type 2 Diabetes

OBJECTIVE

The aim was to evaluate the impact of bariatric surgery on cardiac and sudomotor autonomic C-fiber function in obese subjects with and without Type 2 diabetes mellitus (T2DM), using sudorimetry and heart rate variability (HRV) analysis.

METHOD

Patients were evaluated at baseline, 4, 12 and 24 weeks after vertical sleeve gastrectomy or Roux-en-Y gastric bypass. All subjects were assessed using SudoscanTM to measure electrochemical skin conductance (ESC) of hands and feet, time and frequency domain analysis of HRV, Neurologic Impairment Scores of lower legs (NIS-LL), quantitative sensory tests (QST) and sural nerve conduction studies.

RESULTS

Seventy subjects completed up to 24-weeks of follow-up (24 non-T2DM, 29 pre-DM and 17 T2DM). ESC of feet improved significantly towards normal in T2DM subjects (Baseline = 56.71±3.98 vs 12-weeks = 62.69±3.71 vs 24-weeks = 70.13±2.88, p<0.005). HRV improved significantly in T2DM subjects (Baseline sdNN (sample difference of the beat to beat (NN) variability) = 32.53±4.28 vs 12-weeks = 44.94±4.18 vs 24-weeks = 49.71±5.19, p<0,001 and baseline rmsSD (root mean square of the difference of successive R-R intervals) = 23.88±4.67 vs 12-weeks = 38.06±5.39 vs 24-weeks = 43.0±6.25, p<0.0005). Basal heart rate (HR) improved significantly in all groups, as did weight, body mass index (BMI), percent body fat, waist circumference and high-density lipoprotein (HDL). Glycated hemoglobin (HbA1C), insulin and HOMA2-IR (homeostatic model assessment) levels improved significantly in pre-DM and T2DM subjects. On multiple linear regression analysis, feet ESC improvement was independently associated with A1C, insulin and HOMA2-IR levels at baseline, and improvement in A1C at 24 weeks, after adjusting for age, gender and ethnicity. Sudomotor function improvement was not associated with baseline weight, BMI, % body fat or lipid levels. Improvement in basal HR was also independently associated with A1C, insulin and HOMA2-IR levels at baseline.

CONCLUSION

This study shows that bariatric surgery can restore both cardiac and sudomotor autonomic C-fiber dysfunction in subjects with diabetes, potentially impacting morbidity and mortality.

Alternative Quantitative Tools in the Assessment of Diabetic Peripheral and Autonomic Neuropathy

Here we review some seldom-discussed presentations of diabetic neuropathy, including large fiber dysfunction and peripheral autonomic dysfunction, emphasizing the impact of sympathetic/parasympathetic imbalance. Diabetic neuropathy is the most common complication of diabetes and contributes additional risks in the aging adult. Loss of sensory perception, loss of muscle strength, and ataxia or incoordination lead to a risk of falling that is 17-fold greater in the older diabetic compared to their young nondiabetic counterparts. A fall is accompanied by lacerations, tears, fractures, and worst of all, traumatic brain injury, from which more than 60% do not recover. Autonomic neuropathy has been hailed as the "Prophet of Doom" for good reason. It is conducive to increased risk of myocardial infarction and sudden death. An imbalance in the autonomic nervous system occurs early in the evolution of diabetes, at a stage when active intervention can abrogate the otherwise relentless progression. In addition to hypotension, many newly recognized syndromes can be attributed to cardiac autonomic neuropathy such as orthostatic tachycardia and bradycardia. Ultimately, this constellation of features of neuropathy conspire to impede activities of daily living, especially in the patient with pain, anxiety, depression, and sleep disorders. The resulting reduction in quality of life may worsen prognosis and should be routinely evaluated and addressed. Early neuropathy detection can only be achieved by assessment of both large and small- nerve fibers. New noninvasive sudomotor function technologies may play an increasing role in identifying early peripheral and autonomic neuropathy, allowing rapid intervention and potentially reversal of small-fiber loss.

The effects of indoor and outdoor temperature on metabolic rate and adipose tissue - the Mississippi perspective on the obesity epidemic

Global warming, primarily caused by emissions of too much carbon dioxide, and climate change is a reality. This will lead to more extreme weather events with heatwaves and flooding. Some studies propose an association between thermal exposures and the prevalence of obesity with an increasing trend towards time spent in the thermal comfort zone. Longterm exposure to the thermal comfort zone can lead to a reduction of brown adipose tissue activity with an impact on energy expenditure and thermogenesis. Reduced seasonal cold exposure in combination with reduced diet-induced thermogenesis by a highly palatable high-fat and high-sugar diet and reduced physical activity contribute to the prevalence of obesity and the metabolic syndrome.

The New Age of Sudomotor Function Testing: A Sensitive and Specific Biomarker for Diagnosis, Estimation of Severity, Monitoring Progression, and Regression in Response to Intervention

Sudorimetry technology has evolved dramatically, as a rapid, non-invasive, robust, and accurate biomarker for small fibers that can easily be integrated into clinical practice. Though skin biopsy with quantitation of intraepidermal nerve fiber density is still currently recognized as the gold standard, sudorimetry may yield diagnostic information not only on autonomic dysfunction but also enhance the assessment of the small somatosensory nerves, disease detection, progression, and response to therapy. Sudorimetry can be assessed using Sudoscan™, which measures electrochemical skin conductance (ESC) of hands and feet. It is based on different electrochemical principles (reverse iontophoresis and chronoamperometry) to measure sudomotor function than prior technologies, affording it a much more practical and precise performance profile for routine clinical use with potential as a research tool. Small nerve fiber dysfunction has been found to occur early in metabolic syndrome and diabetes and may also be the only neurological manifestation in small fiber neuropathies, beneath the detection limits of traditional nerve function tests. Test results are robust, accomplished within minutes, require little technical training and no calculations, since established norms have been provided for the effects of age, gender, and ethnicity. Sudomotor testing has been greatly under-utilized in the past, restricted to specialized centers capable of handling the technically demanding and expensive technology. Yet, evaluation of autonomic and somatic nerve function has been shown to be one of the best estimates of cardiovascular risk. Evaluation of sweating has the appeal of quantifiable non-invasive determination of the integrity of the peripheral autonomic nervous system, and can now be accomplished rapidly at point of care clinics with the determination of ESC, allowing intervention for morbid complications prior to permanent structural nerve damage. We review here sudomotor function testing technology, the research evidence accumulated supporting the clinical utility of measuring ESC, the medical applications of sudorimetry now available to physicians with this device, and clinical vignettes illustrating its use in the clinical decision-making process.

Roles of interstitial fluid pH in diabetes mellitus: Glycolysis and mitochondrial function

The pH of body fluids is one the most important key factors regulating various cell function such as enzyme activity and protein-protein interaction via modification of its binding affinity. Therefore, to keep cell function normal, the pH of body fluids is maintained constant by various systems. Insulin resistance is one of the most important, serious factors making the body condition worse in diabetes mellitus. I have recently found that the pH of body (interstitial) fluids is lower in diabetes mellitus than that in non-diabetic control, and that the lowered pH is one of the causes producing insulin resistance. In this review article, I introduce importance of body (interstitial) fluid pH in regulation of body function, evidence on abnormal regulation of body fluid pH in diabetes mellitus, and relationship between the body fluid pH and insulin resistance. Further, this review proposes perspective therapies on the basis of regulation of body fluid pH including propolis (honeybee product) diet.

Sudoscan, a noninvasive tool for detecting diabetic small fiber neuropathy and autonomic dysfunction

OBJECTIVE

Sudomotor dysfunction may be an early detectable abnormality in diabetic small fiber neuropathy. The aim of this study was to evaluate the efficacy of Sudoscan™ (Impeto Medical, Paris, France) in detecting diabetic neuropathy (DN), in comparison with other standardized tests, in patients with diabetes mellitus (DM).

SUBJECTS AND METHODS

Sudoscan measures electrochemical skin conductance (ESC) of hands and feet through reverse iontophoresis. We evaluated 83 DM patients with and without DN and 210 healthy controls (HCs). Neuropathy Impairment Score-Lower Legs (NIS-LL), quantitative autonomic function testing (QAFT), and quantitative sensory testing (QST) were performed. Symptomatic pain was recorded using a visual analog scale. Receiver-operator characteristic (ROC) curves were calculated to evaluate the efficacy of Sudoscan in detecting DN compared with traditional modalities.

RESULTS

Diabetes patients with DN had significantly worse ESCs of feet and hands than DM patients without DN and HCs (respectively, 56.3±3 vs. 75.9±5.5 and 84.4±0.9 [P<0.0001] for feet and 51.9±2.4 vs. 67.5±4.3 and 73.1±0.8 [P<0.0001] for hands). Increasing NIS-LL scores were associated with decreasing ESC values. ESCs correlated significantly with clinical (NIS-LL), somatic (QST), and autonomic (QAFT) measures of neuropathy and with pain scores. ROC curve analysis showed significant results for both hands and feet ESC (area under the curve of 0.86 and 0.88, respectively; P<0.0001) with sensitivity of 78% and specificity of 92% for feet to detect DN.

CONCLUSIONS

Sudoscan is a promising, sensitive tool to detect neuropathy in patients with DM. This is a very simple, easy-to-perform test that can be done in the clinical setting in 3-5 min.