Diabetic peripheral neuropathic pain: clinical and quality-of-life issues

Efficacy and Safety of LX9211 for Relief of Diabetic Peripheral Neuropathic Pain (RELIEF-DPN 1): Results of a Double-Blind, Randomized, Placebo-Controlled, Proof-of-Concept Study

OBJECTIVE

To evaluate the efficacy of LX9211 in reducing pain related to diabetic peripheral neuropathy.

RESEARCH DESIGN AND METHODS

In this double-blind, multicenter, proof-of-concept trial, 319 individuals with diabetic peripheral neuropathic pain (DPNP) were randomized (1:1:1) to LX9211 10 mg (n = 106), LX9211 20 mg (n = 106), or matching placebo (n = 107), administered once daily for 6 weeks. DPNP was rated daily with an 11-point numerical rating scale. The primary end point was change from baseline to week 6 in the average daily pain score. The difference between each LX9211 group and placebo was evaluated with mixed-model repeated-measures analysis.

RESULTS

For those on low-dose LX9211 the primary efficacy end point was achieved: -1.39 vs. -0.72 points for placebo, least squares mean (SE) difference -0.67 (0.249), 95% CI -1.16 to -0.18, P = 0.007; results for high-dose LX9211 demonstrated improvement in pain severity versus placebo (-1.27 vs. -0.72 points, respectively), but the between-group LS mean difference did not reach the prespecified statistical significance (-0.55 [0.254], 95% CI -1.06 to -0.05, P = 0.030). Treatment benefit was observed beginning at week 1 and maintained thereafter. Results for LX9211 also demonstrated improvement in several patient-reported secondary outcomes. Most common adverse events (AEs) were dizziness, nausea, and headache. More participants treated with LX9211 (20 mg, n = 28 [26.4%]; 10 mg, 17 [16.0%]) than placebo (3 [2.8%]) discontinued study drug prematurely due to AEs; serious AEs were uncommon (2 [1.9%], 0, and 1 [0.9%], respectively).

CONCLUSIONS

These preliminary findings of improvement in DPNP with LX9211 support further investigation in larger trials.

The limited role of serum neurofilament light chain in predicting pain severity of patients with diabetic polyneuropathy

Pain is one of many complaints expressed by patients with diabetic polyneuropathy. However, no objective measure for pain severity has been available. Neurofilament light chains have been widely used for assessing axonal damage in the neuronal system. Hence, we sought to investigate whether neurofilament light chains can serve as a marker reflecting pain severity in diabetic polyneuropathy. We enrolled the patients with diabetic polyneuropathy. Serum concentrations of neurofilament light chain were then measured using a single-molecule array. Pain severity was evaluated using painDETECT and the Brief Pain Inventory. Moreover, laboratory results including, serum creatinine, HbA1c, and glomerular filtration rate. A correlation test was used to analyze each variable. A total of 42 patients were enrolled. Neurofilament light chain levels were unable to reflect current neuropathic pain severity. However, high levels of neurofilament light chain were a significant predictor of poor diabetes control (r = 0.41; p = 0.02) and kidney damage (r = 0.45; p = 0.01). Serum levels of neurofilament light chain could not reflect current pain severity but was strongly associated with kidney dysfunction and poor diabetes control. Other biomarkers that could predict pain severity need to be uncovered.

What is associated with painful polyneuropathy? A cross-sectional analysis of symptoms and signs in patients with painful and painless polyneuropathy

ABSTRACT

It is still unclear how and why some patients develop painful and others painless polyneuropathy. The aim of this study was to identify multiple factors associated with painful polyneuropathies (NeuP). A total of 1181 patients of the multicenter DOLORISK database with painful (probable or definite NeuP) or painless (unlikely NeuP) probable or confirmed neuropathy were investigated clinically, with questionnaires and quantitative sensory testing. Multivariate logistic regression including all variables (demographics, medical history, psychological symptoms, personality items, pain-related worrying, life-style factors, as well as results from clinical examination and quantitative sensory testing) and machine learning was used for the identification of predictors and final risk prediction of painful neuropathy. Multivariate logistic regression demonstrated that severity and idiopathic etiology of neuropathy, presence of chronic pain in family, Patient-Reported Outcomes Measurement Information System Fatigue and Depression T-Score, as well as Pain Catastrophizing Scale total score are the most important features associated with the presence of pain in neuropathy. Machine learning (random forest) identified the same variables. Multivariate logistic regression archived an accuracy above 78%, random forest of 76%; thus, almost 4 out of 5 subjects can be classified correctly. This multicenter analysis shows that pain-related worrying, emotional well-being, and clinical phenotype are factors associated with painful (vs painless) neuropathy. Results may help in the future to identify patients at risk of developing painful neuropathy and identify consequences of pain in longitudinal studies.

Peripheral Neuropathy

Peripheral neuropathy is a commonly encountered diagnosis in both neurology and primary care office settings. It is important for primary care providers to identify, characterize, and diagnose patients with neuropathy. This study aims to describe the clinical presentation, diagnostic work up, and treatment options for this entity, as well as the identification of atypical features that should prompt specialized laboratory testing, electrodiagnostic testing, and neurologic consultation.

Decreased glucagon in diabetic peripheral neuropathy patients with long duration type 2 diabetes

OBJECTIVE

The aim of this study was to investigate the association of fasting C-peptide and glucagon with diabetic peripheral neuropathy (DPN) in patients with type 2 diabetes (T2DM).

METHODS

A comprehensive evaluation was conducted on 797 patients with T2DM to assess the various risk factors affecting DPN. The subjects were categorized into short duration and long duration group according to the duration of diabetes with a threshold of 10 years. Logistic regression analysis was employed to examine the association between DPN and islet function, as well as other parameters. Receiver operating characteristic curve analysis was performed to evaluate the predictive capability of glucagon.

RESULTS

The fasting C-peptide levels were significantly lower in the DPN patients with short duration of diabetes, but lost significance in the long duration group. Conversely, a decreased level of glucagon was only observed in DPN patients with long duration of diabetes. For the group with long duration of diabetes, glucagon was the sole risk factor associated with DPN. The receiver operating characteristic curve analysis revealed that glucagon in the long duration group exhibited a moderate area under the curve of 0.706.

CONCLUSIONS

The serum glucagon levels in T2DM patients with DPN exhibited bidirectional changes based on the duration of diabetes. Decreased glucagon was associated with DPN in T2DM patients with long duration of diabetes.

Lumbar radiculopathy and fracture risk: A Korean nationwide population-based cohort study

INTRODUCTION

Lumbar radiculopathy is a common disease with a high economic burden, and fractures in adults are a significant public health problem. However, studies of the relationship between lumbar radiculopathy and fractures are scarce. We investigated the fracture risk in patients with lumbar radiculopathy.

METHODS

This nationwide retrospective cohort study identified 815,101 patients with lumbar radiculopathy and randomly matched individuals without lumbar radiculopathy (1:1) who were included in the Korean National Health Insurance System in 2012. Cox proportional hazards regression analyses were performed to calculate the hazard ratio (HR) for fracture risk in patients with lumbar radiculopathy.

RESULTS

The study included 301,347 patients with lumbar radiculopathy and matched 289,618 individuals without lumbar radiculopathy. Compared to individuals without lumbar radiculopathy, patients with lumbar radiculopathy had a 27 % increased fracture risk (adjusted HR = 1.27, 95 % confidence interval = 1.24-1.31). The Kaplan-Meier plot showed a significantly higher fracture incidence in patients with lumbar radiculopathy than in individuals without lumbar radiculopathy at all times.

CONCLUSION

Lumbar radiculopathy is significantly associated with fracture risk.

Interferon-gamma Treatment of Human Umbilical Cord Mesenchymal Stem Cells can Significantly Reduce Damage Associated with Diabetic Peripheral Neuropathy in Mice

BACKGROUND

Diabetic peripheral neuropathy causes significant pain to patients. Umbilical cord mesenchymal stem cells have been shown to be useful in the treatment of diabetes and its complications. The aim of this study was to investigate whether human umbilical cord mesenchymal stem cells treated with interferon-gamma can ameliorate nerve injury associated with diabetes better than human umbilical cord mesenchymal stem cells without interferon-gamma treatment.

METHODS

Human umbilical cord mesenchymal stem cells were assessed for adipogenic differentiation, osteogenic differentiation, and proliferation ability. Vonfry and a hot disc pain tester were used to evaluate tactile sensation and thermal pain sensation in mice. Hematoxylin-eosin and TUNEL staining were performed to visualize sciatic nerve fiber lesions and Schwann cell apoptosis in diabetic mice. Western blotting was used to detect expression of the apoptosis-related proteins Bax, B-cell lymphoma-2, and caspase-3 in mouse sciatic nerve fibers and Schwann cells. Real-Time Quantitative PCR was used to detect mRNA levels of the C-X-C motif chemokine ligand 1, C-X-C motif chemokine ligand 2, C-X-C motif chemokine ligand 9, and C-X-C motif chemokine ligand 10 in mouse sciatic nerve fibers and Schwann cells. Enzyme-linked immunosorbent assay was used to detect levels of the inflammatory cytokines, interleukin- 1β, interleukin-6, and tumor necrosis factor-α in serum and Schwann cells.

RESULTS

The adipogenic differentiation capacity, osteogenic differentiation capacity, and proliferation ability of human umbilical cord mesenchymal stem cells were enhanced after interferon-gamma treatment. Real-Time Quantitative PCR revealed that interferon-gamma promoted expression of the adipogenic markers, PPAR-γ and CEBP-α, as well as of the osteogenic markers secreted phosphoprotein 1, bone gamma-carboxyglutamate protein, collagen type I alpha1 chain, and Runt-related transcription factor 2. The results of hematoxylin-eosin and TUNEL staining showed that pathological nerve fiber damage and Schwann cell apoptosis were reduced after the injection of interferon-gamma-treated human umbilical cord mesenchymal stem cells. Expression of the apoptosis-related proteins, caspase-3 and Bax, was significantly reduced, while expression of the anti-apoptotic protein B-cell lymphoma-2 was significantly increased. mRNA levels of the cell chemokines, C-X-C motif chemokine ligand 1, C-X-C motif chemokine ligand 2, C-X-C motif chemokine ligand 9, and C-X-C motif chemokine ligand 10, were significantly reduced, and levels of the inflammatory cytokines, interleukin-1β, interleukin-6, and tumor necrosis factor-α, were decreased. Tactile and thermal pain sensations were improved in diabetic mice.

CONCLUSION

Interferon-gamma treatment of umbilical cord mesenchymal stem cells enhanced osteogenic differentiation, adipogenic differentiation, and proliferative potential. It can enhance the ability of human umbilical cord mesenchymal stem cells to alleviate damage to diabetic nerve fibers and Schwann cells, in addition to improving the neurological function of diabetic mice.

Increased Systemic Immune-Inflammation Index Was Associated with Type 2 Diabetic Peripheral Neuropathy: A Cross-Sectional Study in the Chinese Population

Background

Systemic immune-inflammation index (SII), a novel inflammatory marker, has been demonstrated to be associated with type 2 diabetes mellitus (T2DM) and its vascular complications, however, the relation between SII and diabetic peripheral neuropathy (DPN) has been never reported. We aimed to explore whether SII is associated with DPN in Chinese population.

Methods

A cross-sectional study was conducted among 1460 hospitalized patients with T2DM. SII was calculated as the platelet count × neutrophil count/lymphocyte count, and its possible association with DPN was investigated by correlation and multivariate logistic regression analysis, and subgroup analyses.

Results

Patients with higher SII quartiles had higher vibration perception threshold and prevalence of DPN (all P<0.01), and SII was independently positively associated with the prevalence of DPN (P<0.01). Multivariate logistic regression analysis showed that the risk of prevalence of DPN increased progressively across SII quartiles (P for trend <0.01), and participants in the highest quartile of SII was at a significantly increased risk of prevalent DPN compared to those in the lowest quartile after adjustment for potential confounding factors (odds rate: 1.211, 95% confidence intervals 1.045-1.404, P<0.05). Stratified analysis revealed positive associations of SII quartiles with risk of prevalent DPN only in men, people less than 65 years old, with body mass index <24 kg/m2, duration of diabetes >5 years, hypertension, dyslipidaemia, poor glycaemic control, and estimated glomerular filtration rate <90 mL/min/1.73 m2 (P for trend <0.01 or P for trend <0.05). The receiver operating characteristic curve analysis revealed that the optimal cut-off point of SII for predicting DPN was 617.67 in patients with T2DM, with a sensitivity of 45.3% and a specificity of 73%.

Conclusion

The present study showed that higher SII is independently associated with increased risk of DPN, and SII might serve as a new risk biomarker for DPN in Chinese population.

Trends in Pain Medication Use in Patients With Type 2 Diabetes: NHANES 2005-2018

The aim of this research was to compare pain medication use trends among adults with and without type 2 diabetes in the US. This cross-sectional study used data of adults with and without (type 2) diabetes from the National Health and Nutrition Examination Survey waves 2005-2018. Use of pain medication including opioids, prescription nonsteroidal anti-inflammatory drugs, gabapentinoids, serotonin norepinephrine reuptake inhibitors, skeletal muscle relaxants, and headache treatment agents was compared by diabetes status and within select social determinants of health and clinical factors. Adults with type 2 diabetes were twice as likely to be prescribed pain medications compared to those without a diabetes diagnosis (16.2% vs 8.6%). Females and those with a history of smoking or arthritis were more likely to be on pain medications. Opioid use was the most prevalent regardless of diabetes status, and use was twice as high among those with diabetes (10.8% vs 5.5%). Patients with type 2 diabetes in the US are twice as likely to be prescribed pain medications overall as well as opioids compared with those without diabetes. Clinical guideline recommendations are necessary to find pharmacologic and nonpharmacologic nociceptive pain management specific for patients with diabetes.

Methods for evaluation of corneal nerve fibres in diabetes mellitus by in vivo confocal microscopy: a scoping review protocol

INTRODUCTION

Globally, 422 million people have diabetes. Late complications of diabetes are blindness, kidney failure, heart attack, stroke and lower limb amputation. The prevalence of diabetic peripheral neuropathy and diabetic retinopathy is 50% and 35%, respectively. In vivo confocal microscopy (IVCM) is a rapid, non-invasive method to evaluate subbasal corneal nerve fibres, which are small fibres of the peripheral nervous system. Corneal nerve fibre changes can be a marker of diabetic peripheral neuropathy. There is currently no gold-standard procedure for IVCM imaging, image processing or quantitative analysis of the corneal nerve fibres in the subbasal plexus. This protocol describes a scoping review to map, summarise and critically evaluate current methods used with IVCM evaluation in people with diabetes mellitus.

METHODS

The scoping review will follow Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines for scoping review. A comprehensive search of the literature will be conducted in MEDLINE, Embase, Cochrane, Scopus and Web of Science. The search strategy will include terms related to IVCM, diabetes and corneal nerve fibres. We will set inclusion and exclusion criteria prior to the search, and two reviewers will screen titles and abstracts independently. One reviewer will full text read eligible articles and chart data from the studies. A descriptive summary of the methods used in imaging, image processing and quantitative analysis of peripheral corneal nerve fibres by IVCM will be written.

ETHICS AND DISSEMINATION

Ethical approval is not required since this is a scoping review based on previously published articles. The findings will be published in a scientific peer-reviewed journal.

Hypertension the 'Missed Modifiable Risk Factor' for Diabetic Neuropathy: a Systematic Review

Diabetes and hypertension stand as the major non-infectious diseases affecting 34.2 million and 1.28 billion people respectively. The literature on the impact of diabetes on hypertension and vice versa is evolving. The major objectives of this review were to compile the evolving literature establishing the role of hypertension in diabetic neuropathy, derive the exact mechanisms for its pathogenesis, and describe evidence-based precise individualized management of diabetic neuropathy in patients having diabetes complicated by hypertension. A systematic review was conducted by searching databases of PubMed, Embase, and Scopus covering the literature from inception to 2022. We included all observational and experimental studies, including both human and animal studies looking into the correlation between diabetic neuropathy and hypertension. Hypertension poses to be the leading modifiable risk factor for the development of diabetic neuropathy, especially distal symmetrical polyneuropathy, producing abnormal nerve conduction parameters and increased vibration perception threshold in patients with diabetes mellitus. Thus, we advocate that good glycemic control in patients with diabetes needs to be supported with strict blood pressure control for preventing and delaying the onset of diabetic neuropathy.

Aspartate aminotransferase/alanine aminotransferase ratio was associated with type 2 diabetic peripheral neuropathy in a Chinese population: A cross-sectional study

OBJECTIVE

Despite previous research that focused on aspartate aminotransferase/alanine aminotransferase ratio (AAR) as predictors of type 2 diabetes mellitus (T2DM) and cardiovascular disease, there has been limited research evaluating the association between AAR and diabetic microvascular complications. This study aimed to investigate the association of AAR with diabetic peripheral neuropathy (DPN).

METHODS

A total of 1562 hospitalized patients with T2DM were divided into four groups according to AAR quartiles. The relationship between AAR and DPN and related parameters was explored by the Spearman correlation coefficients, multivariable logistic regression analysis, and receiver operating characteristic (ROC) curves.

RESULTS

Patients with higher AAR quartiles had higher levels of vibration perception threshold (VPT) and presence of DPN, and AAR was positively associated with VPT and presence of DPN independent of sex, age, body mass index, and diabetic duration (P<0.01 or P<0.05). Moreover, AAR remained significantly associated with a higher odds ratio (OR) of DPN (OR 2.413, 95% confidence interval [CI] 1.081-5.386, P<0.05) after multivariate adjustment. Additionally, the risk of presence of DPN increased progressively as AAR quartiles increased (all P for trend <0.01) in both male and female subjects, and the highest quartile of AAR of male and female subjects was respectively associated with 107.3% (95% CI: 1.386-3.101; P<0.01) and 136.8% (95% CI: 1.550-3.618; P<0.01) increased odds of DPN compared with the lower quartiles. Last, the analysis of receiver operating characteristic curves revealed that the best cutoff values for AAR to predict the presence of DPN were 0.906 (sensitivity: 70.3%; specificity: 49.2%; and area under the curve [AUC]: 0.618) and 1.402 (sensitivity: 38%; specificity: 81.9%; and AUC: 0.600) in male and female subjects, respectively.

CONCLUSIONS

These findings suggest that the high AAR may be associated with the presence of DPN in Chinese patients with T2DM, and may be used as an additional indicator of risk of DPN.

The Interaction of Diabetic Peripheral Neuropathy and Carpal Tunnel Syndrome

BACKGROUND

Diabetes mellitus (DM) increases the risk for carpal tunnel syndrome (CTS) and is associated with its own neuropathic complications. Diabetic peripheral neuropathy (DPN) is a common complication seen in diabetic patients. In this study, we examine the relationship between the severity of DPN and CTS.

METHODS

Type 2 diabetic and control patients (n = 292) were recruited at a clinic visit. The Michigan Neuropathy Screening Instrument (MNSI) questionnaire was used to collect data related to peripheral neuropathy. The MNSI scores were compared for patients with CTS with and without DM in univariable and multivariable analyses. χ2 analyses were performed to quantitatively measure the associations between peripheral neuropathy and the presence of CTS.

RESULTS

Of the 292 patients, 41 had CTS, and 19 of these had both CTS and DM. Of the 138 diabetic patients, 85 had peripheral neuropathy. There was no association between a diagnosis of CTS and an MNSI score indicative of peripheral neuropathy. In the diabetic population, CTS was inversely associated with DPN (P = .017). The MNSI scores between diabetic and control patients with CTS were comparable.

CONCLUSION

The severity of peripheral neuropathy in diabetic patients with and without CTS is comparable. Diabetic patients without peripheral neuropathy have an association with higher incidence of CTS in this study, suggesting that there are disparate mechanisms causing DPN and CTS. Nevertheless, diabetes and CTS are risk factors for developing the other, and future studies should further explore how DPN and CTS differ to tailor patient interventions based on their comorbidities.

The relationship between vascular endothelial growth factor-A serum level and the severity of diabetic peripheral neuropathy

Background and aims

Diabetic peripheral neuropathy (DPN) is a common microvascular complication in type 2 diabetes mellitus (T2DM). The nerve fibers injury is caused by the interaction between metabolic and vascular factors. Vascular endothelial growth factor (VEGF) is an essential growth factor for vascular endothelial cells. We aimed to investigate the relation between VEGF-A serum level and the degree of DPN.

Results

This cross-sectional study was conducted on 81 patients with T2DM. Based on the combined clinical and electrophysiological assessment, 67 patients (82.7%) were diagnosed with peripheral neuropathy of which 32 patients (39.5%) had subclinical neuropathy, whereas 35 patients (43.2%) were confirmed cases of DPN. Patients with DPN had longer duration of DM and higher values of glycosylated hemoglobin (HbA1c). Although the mean serum VEGF-A level in diabetic patients without neuropathy was higher than that in diabetic patients with DPN, this difference did not reach statistical significance (P = 0.07). However, patients with subclinical DPN had significantly higher serum VEGF-A level compared to patients with confirmed DPN (P < 0.001).

Conclusion

DPN was found to be a common finding in the studied sample of T2DM patients. Longer duration of DM and poor glycemic control may be risk factors for development of severe DPN. Low VEGF-A serum levels may lead to more severe DPN in patients with T2DM.

Changed cerebral function and morphology serve as neuroimaging evidence for subclinical type 2 diabetic polyneuropathy

Introduction

Central and peripheral nervous systems are all involved in type 2 diabetic polyneuropathy mechanisms, but such subclinical changes and associations remain unknown. This study aims to explore subclinical changes of the central and peripheral and unveil their association.

Methods

A total of 55 type-2 diabetes patients consisting of symptomatic (n = 23), subclinical (n = 12), and no polyneuropathy (n = 20) were enrolled in this study. Cerebral morphology, function, peripheral electrophysiology, and clinical information were collected and assessed using ANOVA and post-hoc analysis. Gaussian random field correction was used for multiple comparison corrections. Pearson/Spearman correlation analysis was used to evaluate the association of the cerebral with the peripheral.

Results

When comparing the subclinical group with no polyneuropathy groups, no statistical differences were shown in peripheral evaluations except amplitudes of tibial nerves. At the same time, functional connectivity from the orbitofrontal to bilateral postcentral and middle temporal cortex increased significantly. Gray matter volume of orbitofrontal and its functional connectivity show a transient elevation in the subclinical group compared with the symptomatic group. Besides, gray matter volume in the orbitofrontal cortex negatively correlated with the Neuropathy Symptom Score (r = -0.5871, p < 0.001), Neuropathy Disability Score (r = -0.3682, p = 0.009), and Douleur Neuropathique en 4 questions (r = -0.4403, p = 0.003), and also found correlated positively with bilateral peroneal amplitude (r > 0.4, p < 0.05) and conduction velocities of the right sensory sural nerve(r = 0.3181, p = 0.03). Similarly, functional connectivity from the orbitofrontal to the postcentral cortex was positively associated with cold detection threshold (r = 0.3842, p = 0.03) and negatively associated with Neuropathy Symptom Score (r = -0.3460, p = 0.01).

Discussion

Function and morphology of brain changes in subclinical type 2 diabetic polyneuropathy might serve as an earlier biomarker. Novel insights from subclinical stage to investigate the mechanism of type 2 diabetic polyneuropathy are warranted.

Magnitude of diabetic peripheral neuropathy in Saudi Arabia: a systematic review and meta-analysis

BACKGROUND

Diabetic peripheral neuropathy (DPN), due to its potential for causing morbidity and disability from foot ulcers and amputations, is increasingly becoming a source of concern in Saudi Arabia and worldwide. However, wide variability exists in the prevalence of DPN reported in previous studies in Saudi Arabia, limiting the utility of existing data in national public health policy. Therefore, the aim of this study was to systematically evaluate the magnitude of DPN in patients living with DM in Saudi Arabia in order to inform policymakers during the implementation of appropriate preventive and treatment strategies for DPN.

METHODS

PubMed, Google Scholar, African Journals Online, Scopus, Web of Science, Embase, and Wiley Online Library were searched systematically to acquire relevant articles based on preset criteria. We evaluated heterogeneity and publication bias and employed a random-effects model to estimate the pooled prevalence of DPN from the included studies. We followed the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines in conducting the meta-analysis. Analysis was performed using the STATA Version 12 software.

RESULTS

Twelve studies with a total of 4,556 participants living with DM, of whom 2,081 were identified as having DPN were included in the meta-analysis. The overall prevalence of DPN was 39% (95% CI [30%, 49%]). Subgroup analysis based on diagnostic method showed that prevalence estimates for DPN using screening questionnaires and clinical examination were 48% (95% CI [46%, 50%]) and 40% (95% CI: [38%, 42%]), respectively, while the estimated prevalence using nerve conduction studies was 26% (95% CI [15%, 36%]).

CONCLUSION

This study showed a high magnitude of DPN in Saudi Arabia (39%), thus highlighting the need for sustained efforts to reduce the prevalence of diabetes mellitus and DPN in the kingdom.

Intravenous Lidocaine for Treatment of Chronic Pain: A Retrospective Cohort Study

Introduction

Neuropathic pain is a widespread problem with a big impact on quality of life. The currently used drug regimens are often insufficiently effective or cause - sometimes unacceptable - side effects. Intravenous lidocaine could be an alternative treatment, by blocking spontaneous depolarization and hyperexcitability in upregulated sodium channels in nociceptors. Research so far has shown varying results but the treatment protocols differed a lot and follow-up was usually short. In our hospital, lidocaine infusions have been applied for many years in a unique treatment protocol consisting of a relatively high dose of lidocaine (1000 mg) administered over 25 hours. Our aim is to share information on both the efficacy and safety of this treatment schedule.

Methods

We conducted a retrospective cohort study in all patients who received a lidocaine infusion between January 2014 and January 2018. The standard infusion protocol consists of a total of 1000 mg lidocaine administered intravenously during 25 hours (40 mg/hour). Pain diagnoses were stratified into 15 groups, in agreement with diagnoses used in daily practice. Effectiveness of the treatment was classified as effect or no effect based on the description found in the chart.

Results

We included 282 patients, with a median age of 58 years and 64% of whom were female. Patients with myofascial pain syndrome, peripheral (mono)neuropathy, small fiber neuropathy and vascular disease benefited most. Patients with cancer pain, postherpetic neuralgia, chemotherapy-induced neuropathy and radicular pain showed the least pain improvement. There were no serious adverse events.

Conclusion

In selected patients, lidocaine infusions may be a safe and efficacious treatment for chronic neuropathic pain. More prospective research is needed to further determine the optimal dosing, duration and interval of lidocaine infusion therapy, and to better understand in which specific patient categories this treatment is most beneficial.

Social Care Recommendations in National Diabetes Treatment Guidelines

PURPOSE OF REVIEW

An expanding body of research documents associations between socioeconomic circumstances and health outcomes, which has led health care institutions to invest in new activities to identify and address patients' social circumstances in the context of care delivery. Despite growing national investment in these "social care" initiatives, the extent to which social care activities are routinely incorporated into care for patients with type II diabetes mellitus (T2D), specifically, is unknown. We conducted a scoping review of existing T2D treatment and management guidelines to explore whether and how these guidelines incorporate recommendations that reflect social care practice categories.

RECENT FINDINGS

We applied search terms to locate all T2D treatment and management guidelines for adults published in the US from 1977 to 2021. The search captured 158 national guidelines. We subsequently applied the National Academies of Science, Engineering, and Medicine framework to search each guideline for recommendations related to five social care activities: Awareness, Adjustment, Assistance, Advocacy, and Alignment. The majority of guidelines (122; 77%) did not recommend any social care activities. The remainder (36; 23%) referred to one or more social care activities. In the guidelines that referred to at least one type of social care activity, adjustments to medical treatment based on social risk were most common [34/36 (94%)]. Recommended adjustments included decreasing medication costs to accommodate financial strain, changing literacy level or language of handouts, and providing virtual visits to accommodate transportation insecurity. Ensuring that practice guidelines more consistently reflect social care best practices may improve outcomes for patients living with T2D.

Pro-inflammatory cytokines and leukocyte integrins associated with chronic neuropathic pain in traumatic and inflammatory neuropathies: Initial observations and hypotheses

Leukocyte infiltration and persistence within peripheral nerves have been implicated in chronic nociception pathogenesis in murine peripheral neuropathy models. Endoneurial cytokine and chemokine expression contribute to leukocyte infiltration and maintenance of a pro-inflammatory state that delays peripheral nerve recovery and promotes chronic pain behaviors in these mice. However, there has been a failure to translate murine model data into safe and effective treatments for chronic neuropathic pain in peripheral neuropathy patients, or develop reliable biomarkers that may help diagnose or determine treatment responses in affected patients. Initial work showed that persistent sciatic nerve CD11b+ CD45+ leukocyte infiltration was associated with disease severity in three mouse models of inflammatory and traumatic peripheral neuropathies, implying a direct contributing role in disease pathogenesis. In support of this, CD11b+ leukocytes were also seen in the sural nerve biopsies of chronic neuropathic pain patients with three different peripheral neuropathies. Systemic CD11b antagonism using a validated function-neutralizing monoclonal antibody effectively treated chronic nociception following unilateral sciatic nerve crush injury (a representative traumatic neuropathy model associated with axonal degeneration and increased blood-nerve barrier permeability) and does not cause drug addiction behaviors in adult mice. These data suggest that CD11b could be an effective molecular target for chronic neuropathic pain treatment in inflammatory and traumatic peripheral neuropathies. Despite known murine peripheral neuropathy model limitations, our initial work suggests that early expression of pro-inflammatory cytokines, such as tissue inhibitor of metalloproteinases-1 may predict subsequent chronic nociception development following unilateral sciatic nerve crush injury. Studies aligning animal model investigation with observational data from well-characterized human peripheral neuropathies, including transcriptomics and proteomics, as well as animal model studies using a human clinical trial design should foster the identification of clinically relevant biomarkers and effective targeted treatments with limited addiction potential for chronic neuropathic pain in peripheral neuropathy patients.

Matrix Metalloproteinase-2 (MMP-2) and-9 (MMP-9) Gene Variants and Microvascular Complications in Type 2 Diabetes Patients

Vascular complications are the leading cause of increased morbidity and mortality of diabetic patients. It has been postulated that matrix metalloproteinases MMP-2 and MMP-9, zinc-dependent endopeptidases through remodeling of the extracellular matrix, can contribute to the onset and progression of diabetic vascular complications. The aim of our study was to assess whether there is a major difference in single nucleotide polymorphisms in the MMP-2 (at position -1306C˃T) and MMP-9 (at position -1562C˃T) gene in type 2 diabetic patients and healthy controls and to determine whether there is an association of these gene variants with the presence of microvascular complications in diabetic patients. Our study included 102 type 2 diabetes patients and a control group which was comprised of 56 healthy controls. All diabetic patients were screened for microvascular diabetes complications. Genotypes were detected by polymerase chain reactions followed by restriction analyses with specific endonucleases and their frequencies were determined. The MMP-2 variant -1306C>T showed a negative correlation with type 2 diabetes (p=0.028). It was also shown that the presence of the -1306C allele increases the probability of developing type 2 diabetes. This was a 2.2 fold increase and that the -1306 T allele has a protective role in regards to type 2 diabetes. The MMP-2 variant -1306T showed a negative correlation with diabetic polyneuropathy (p=0.017), meaning that allele-1306T has a protective role in regards to diabetic polyneuropathy while the presence of allele -1306C increases the probability of developing diabetic polyneuropathy by 3.4 fold. Our study showed that the MMP-2 gene variant (-1306C) doubles the risk of developing type 2 diabetes, and for the first time an association of this gene variant and the presence of diabetic polyneuropathy was shown.

Peripheral Neuropathies Derived from COVID-19: New Perspectives for Treatment

Peripheral neuropathies constitute a group of disorders affecting the peripheral nervous system. Neuropathies have multiple causes such as infections (i.e., COVID-19), diabetes, and nutritional (low vitamin levels), among others. Many micronutrients, such as vitamins (A, C, D, E, B6, B12, and folate), certain minerals (Fe, Mg, Zn, Se, and Cu), and ω-3 fatty acids have immunomodulatory effects. Therefore, they may play an instrumental role in the treatment of COVID-19 infection. However, many COVID-19 patients can undergo neuropathy. In this context, there is a wealth of information on a variety of first-, second-, and third-line treatment options. This review focuses on the application of nutraceutical strategies in order to improve the symptomatology of neuropathy and neuropathic pain in patients that suffered from COVID-19. Our aim is to provide an alternative vision to traditional medical-pharmacological treatment through nutraceuticals.

Efficacy and safety of Mudan granules for painful diabetic peripheral neuropathy: A protocol for a double-blind randomized controlled trial

BACKGROUND

As one of the most challenging complications in the management of diabetes mellitus, painful diabetic peripheral neuropathy (PDPN) is accompanied by various clinical manifestations, including numbness, burning, coldness, and other sensory abnormalities in the extremities. Meanwhile, PDPN seriously affects the life quality of patients and causes great pain. Western medicine mostly provides symptomatic treatments, such as antioxidants, aldose reductase inhibitors, nerve nutrition, microcirculation improvement, and analgesic drugs on the basis of blood sugar control. Although certain efficacy has been achieved, the problem has not been solved at root. Mudan granules have some advantages in the treatment of PDPN, but there is insufficient high-quality clinical studies to verify this. Therefore, the purpose of this study was to evaluate the efficacy and safety of Mudan granules in treating PDPN.

METHODS

A randomized, double-blind, placebo, and parallel-controlled trial design was used to study the efficacy and safety of Mudan granules in the treatment of PDPN. In this study, 93 patients with painful diabetic neuropathy were recruited and randomly divided into a treatment group and a placebo group based on 1:1. The treatment group was given Mudan granules and the control group accepted placebo treatment, and the basic treatment was performed according to the recommended guidelines. During the treatment period, the patients' visual analog scores, clinical efficacy, Medical Outcomes Study 36-item Short-Form Health Survey (SF-36) scores, nerve conduction velocity, and drug-induced adverse reactions were observed at baseline after 8 and 10 weeks.

DISCUSSION

This study will evaluate the efficacy and safety of Mudan granules in treating PDPN. The experimental results will provide evidence support to treat PDPN with Mudan granules.

TRIAL REGISTRATION

DOI 10.17605/OSF.IO/5CE32.

Determinants of Diabetic Peripheral Neuropathy and Their Clinical Significance: A Retrospective Cohort Study

BACKGROUND

In this study, we investigated the epidemiological characteristics and predictors of diabetic peripheral neuropathy (DPN) in adult patients with type 2 diabetes mellitus (DM).

METHODS

The study was designed as a retrospective cohort trial at the First Affiliated Hospital of Wenzhou Medical University. From January 2017 to December 2020, a total of 1,262 patients with DM were enrolled to assess the risk factors for DPN. The patients were divided into two groups (DPN group and non-DPN group). The Mann-Whitney U test or t-test, receiver operating characteristic (ROC) analyses, univariate chi-square analyses, and multiple logistic regression analyses were used to analyze the adjusted predictors of DPN.

RESULTS

The overall prevalence of DPN in DM patients was 72.7% (n = 793/1,091). Multivariate analysis revealed that age > 66 years (odds ratio [OR], 2.647; 95% confidence interval [CI] 1.469-4.770; p = 0.002), history of hypertension (OR, 1.829; 95% CI 1.146-2.920; p = 0.011), neutrophil (NE) levels exceeding 4.0 × 10⁹/L (OR 0.256; 95% CI 0.162-0.405; p = 0.001), lymphocyte (LY) levels over 3.0 × 10⁹/L (OR 7.173; 95% CI 4.258-12.086; p = 0.000), HbA1c > 7.7% (OR 3.151; 95% CI 1.959-5.068; p = 0.000), and FT3 > 4.4 pmol/L (OR 0.417; 95% CI 0.263-0.662; p = 0.000) were six significant predictive factors for the prevalence of DPN.

CONCLUSIONS

High levels of LY, HbA1c, history of hypertension, and > 66 years of age increase the risk of DPN in adult patients with DM, while high levels of NE and FT3 were protective factors of DPN. Thus, the prediction of DPN can significantly be improved by identifying older patients over the age of 66 and history of hypertension, as well as establishing the biochemical cutoff values of NE, LY, HbA1c, and FT3.

Serum free triiodothyronine is inversely associated with diabetic peripheral neuropathy but not with carotid atherosclerotic lesions in euthyroid patients with type 2 diabetes

BACKGROUND

The associations between serum free triiodothyronine (FT3) and diabetic peripheral neuropatprohy (DPN)/carotid atherosclerotic lesions in euthyroid patients with type 2 diabetes are still unclear. The purpose of our study was to explore the relations of FT3 to DPN and carotid atherosclerotic lesions in Chinese type 2 diabetes inpatients with euthyroid function.

METHODS

2477 euthyroid inpatients with type 2 diabetes were recruited and they were stratified into quartiles by FT3 levels in this cross-sectional study. Peripheral neuropathy was assessed by neurological symptoms and signs as well as nerve conduction velocity tests. Carotid atherosclerotic lesions, including carotid intima-media thickness, plaque and stenosis, were evaluated by Doppler ultrasound.

RESULTS

The prevalence of DPN in type 2 diabetic patients exhibited the significant decrease across the FT3 quartiles (23.5%, 20.9%, 18.8%, and 11.2%, respectively, p < 0.001). Multiple logistical regression analysis also revealed that FT3 quartiles were significantly and inversely associated with DPN. Compared with the subjects in the highest FT3 quartile, the adjusted odds ratios (95% confidence interval) of DPN from the first to third FT3 quartile were successively 2.338 (1.407-3.884), 1.903 (1.134-3.194) and 1.598 (0.960-1.125). The patients with DPN had significantly higher prevalence of carotid atherosclerotic lesions compared with non-DPN patients. However, no statistical association was observed between FT3 quartiles and carotid atherosclerotic lesions after adjusting for confounder factors.

CONCLUSIONS

Lower FT3 within the normal range was independently associated with DPN, but not with carotid atherosclerotic lesions in Chinese euthyroid inpatients with type 2 diabetes.

Association of Diabetic Peripheral Neuropathy with Vitamin D Levels Depends on Vitamin D Status

Background

Vitamin D deficiency has been reported to be associated with diabetic peripheral neuropathy (DPN). Our objective here was to evaluate the association between vitamin D levels and neuropathic symptoms in a Chinese population.

Material/Methods

A total of 4435 patients with type 2 diabetes (T2D) were recruited in this cross-sectional study. 25-dihydroxyvitamin D (25-(OH) D) serum concentration was measured by electrochemiluminescence assay (Cobas e601, Roche). DPN was clinically diagnosed by assessing neurological symptoms and performing current perception threshold (CPT) testing. Of all the patients, 2910 were CPT-positive and had assessed neurological symptoms.

Results

In the vitamin D insufficiency group (<30 ng/mL 25-(OH) D), patients with neurological symptoms had higher serum 25-(OH) D levels than those without neurological symptoms (24.65±3.42 ng/mL vs 23.61±4.54 ng/mL, p≤0.001). The risk of numbness and pain increased by 0.5-fold for every 6 ng/mL increase in 25-(OH) D. In the vitamin D sufficiency group (≥30 ng/mL 25-(OH) D), patients with neurological symptoms had lower serum 25-(OH) D levels than those without neurological symptoms (32.96±3.18 ng/mL vs 33.45±4.27 ng/mL, p<0.01). For every 4 ng/mL decrease in 25-(OH) D, the risk of numbness and pain increased by 0.2-fold.

Conclusions

The association of neuropathy symptoms with 25-(OH) D levels differed depending on whether the patients had insufficient or sufficient vitamin D.

Peripheral blood levels of CXCL10 are a useful marker for diabetic polyneuropathy in subjects with type 2 diabetes

BACKGROUND

Diabetic peripheral neuropathy (DPN) is a chronic complication of diabetes mellitus associated with high morbidity and mortality. Major risk factors for DPN include metabolic changes, duration of diabetes, nerve ischaemia and derangements in regeneration and nerve repair programmes. Chemokines have been previously implicated in the pathogenesis of various neuropathies and neuropathic pain processes. The aim of this pilot study was to evaluate the association between the plasma levels of chemokines (CXCL9, CXCL10 and CXCL11) in the presence of DPN in a cohort of type 2 diabetes (T2D) patients.

MATERIALS AND METHODS

We studied 73 patients with T2D: 36 with DPN and 37 without DPN. DPN was established through the Semmes-Weinstein test (SW). Plasma levels of circulating chemokines CXCL9, CXCL10 and CXCL11 were determined using DuoSet ELISA kits (Abingdon, UK).

RESULTS

We found that levels of CXCL10 were significantly higher in patients with DPN than amongst patients without DPN (57.6 ± 38.3 vs 38.1 ± 33.4 pg/mL, respectively; P = .034). Serum levels of chemokine CXCL9 were also higher amongst patients with DPN but did not reach a statistical significance (188.1 ± 72.7 and 150.4 ± 83.6 pg/mL, respectively, P = .06).

CONCLUSIONS

Increased circulating levels of CXCL10 were associated with DPN in T2D patients, suggesting a role of this chemokine in the DPN. Determination of CXCL10 levels could be used as a marker for the early detection and implementation of therapeutic strategies in order to reverse and prevent the DPN.

Influence of Pain on the Quality of Life and Disease Acceptance in Patients with Complicated Diabetic Foot Syndrome

OBJECTIVE

The aim of the study was to evaluate the relationship between pain and quality of life and illness acceptance, anxiety and depression in a group of patients with complicated diabetic foot syndrome, following lower limb amputation.

PATIENTS AND METHODS

The studies were carried out in three stages: 7 days, 6 months and 12 months after surgery in a group of 100 patients after amputation of the lower limb due to complications resulting from type 2 diabetes. The study was performed using standardised instruments: WHOQOL-BREF, the Acceptance of Illness Scale (AIS), the Hospital Anxiety and Depression Scale (HADS), and the Visual Analog Scale (VAS) for pain intensity assessment.

RESULTS

Pain occurred in the examined patients throughout the study. The greatest intensity of pain was observed in the postoperative period and significantly weakened over time. Pain intensity was significantly associated with worse overall QoL perceived (-0.255, p=0.011/-0.283, p=0.005) and QoL scores in the physical and psychological domains at the first and second stage of the study (physical domains -0.257, p=0.011/-0.219, p=0.03 and psychological -0.22, p=0.029/-0.24/0.018). The intensity of pain negatively correlates with the acceptance of the disease in all three stages of the study, the greater the severity of pain, the lower the acceptance of illness (-0.298, p=0.003/-0.326, p=0.001/-0.26, p=0.009). The occurrence of anxiety and depression is highly dependent on the severity of pain, especially at the first and second stage of the study (anxiety 0.203, p=0.045/0.257, p=0.01, depression 0.299, p=0.003/0.253, p=0.012). The stronger the pain, the greater the severity of mood disorders.

CONCLUSION

Pain and its severity are associated with QoL in the patients with complicated diabetic foot syndrome following lower limb amputation. Disease acceptance was lower in patients experiencing more severe pain at all stages of the study. There is an association of pain with the occurrence of anxiety and depression in amputees, especially 6 months after surgery.

Ameliorative effects of escin on neuropathic pain induced by chronic constriction injury of sciatic nerve

ETHNOPHARMACOLOGY RELEVANCE

Escin is a natural mixture of triterpene saponins extracted from the seeds of Aesculus wilsonii Rehd. And has been reported to possess the therapeutic effects against neuropathic pain (NP). However, the underlying mechanisms remain unclear.

AIM OF THE STUDY

The present study aimed to investigate the therapeutic effects and explore the underlying mechanisms of escin on rats of NP induced by chronic constriction injury (CCI) of sciatic nerve.

MATERIALS AND METHODS

Rats were treated with escin (7, 14, and 28 mg/kg, i. g.) daily from the third day after the surgery (day 0) for consecutive 14 days. Regular behavior and thermal threshold were measured on days 0, 3, 5, 7, 10 and 14. Investigations into mechanisms involved measurement of inflammatory factors and biochemical factors in dorsal root ganglion (DRG). Inflammatory pain responses and nerve injuries were induced by the CCI model. Tonic pain model and acute inflammatory model induced by formalin or carrageenan were established to evaluated the pharmacological effects of escin on acute inflammatory pain. Corresponding behaviors were monitored and relevant gene expression such as c-fos, mu opioid receptor (MOR) and KCNK1 were detected by qRT-PCR. Investigate the neuroprotective effects of escin on PC12 cell injury induced by lipopolysaccharide (LPS). Cell morphology was observed under inverted microscope and neuroprotective effect of escin on cell activity was assessed by MTT assay.

RESULTS

Escin could widen thermal threshold, downregulate the concentration of inflammatory factors like tumor necrosis factor (TNF)-α and interleukin (IL)-1β, suppress the gene expression of toll-like receptor 4 (TLR4), nuclear factor κB (NF-κB), decrease the level of glial fibrillary acidic protein (GFAP) and nerve growth factor (NGF) remarkably. In addition, escin significantly lowered the duration of licking, numbers of flinches and increase in paw edema, showing great therapeutic effects on inflammatory pain responses. Moreover, the activity of injured PC12 cells was significantly improved after escin administrated.

CONCLUSION

Escin exerted the ameliorative effects on NP induced by CCI which may be related to downregulating the release of pro-inflammatory cytokines, suppressing TLR-4/NF-κB signal pathway, thereafter decreasing the level of GFAP and NGF.

Development and Comparative Efficacy of Lagos Neuropathy Protocol for Improving Recovery of Symptom and Functional Independence Performance in Individuals with Diabetic Peripheral Sensorimotor Polyneuropathy

BACKGROUND

Diabetic peripheral sensorimotor polyneuropathy (DPSP) has been treated with sketchy outcomes and available approaches are not applicable for self-administration. This study developed protocol for managing symptoms of DPSP and assessed its comparative efficacy.

METHODS

Study developed Lagos Neuropathy Protocol (LNP) through existing concept in DPSP and tested its safety, clinical applicability, and ease of self-administration. Its efficacy was compared with Buerger-Allen Exercise (BAE) by involving 31(11males) with DPSP, randomized into LNP and BAE and treated for 10-week. Toronto Clinical Scoring System was used to diagnose DPSP while Diabetic Neuropathy Examination was used to diagnose distal polyneuropathy. Sensory/pressure perception was assessed using 10 g-monofilament while Short Physical Performance Battery, Bergs Balance Scale and Visual Analogue Scale was used to assess functional performance, strength and balance, and pain respectively.

RESULTS

LNP has three domains: sensory/pressure/proprioception, strength/balance, and pain/swelling. Most (80%) of the participants rated the LNP as excellently safe while the rest (20%) rated as very good in safety. All the participants rated LNP excellent in terms of self-administration and suitability for clinical use without adverse effect. The mean age of the participants for the comparative phase was 66.20±9.48years while their length of diagnoses of diabetes was 15.80±13.35years. About a third (32.5%) had DPSP. Both LNP and BAE had significant improvement (p<0.05) in sensory/pressure perception, pain, strength and balance, and functional performance but LNP had better significant improvement.

CONCLUSION

LNP is safe, good for self-administration, clinically applicable and efficacious in improving sensory/pressure perception, balance, pain and functional performances in individuals with DPSP.

Peripheral neuropathic pain

Neuropathic pain (NP) can have either central nervous system causes or ones from the peripheral nervous system. This article will focus on the epidemiology, classifications, pathology, non-invasive treatments and invasive treatments as a general review of NP involving the peripheral nervous system. NP has characteristic symptomatology such as burning and electrical sensations. It occurs in up to 10% of the general population. Its frequency can be attributed to its occurrence in neck and back pain, diabetes and patients receiving chemotherapy. There are a wide range of pharmacologic options to control this type of pain and when such measures fail, numerous interventional methods can be employed such as nerve blocks and implanted stimulators. NP has a cost to the patient and society in terms of emotional consequences, quality of life, lost wages and the cost of assistance from the medical system and thus deserves serious consideration for prevention, treatment and control.

Variables predicting prognosis following nerve mobilisation in individuals with cervicobrachial pain

Background/Aims

The causes of cervicobrachial pain are highly variable and it is often difficult to predict patient response to multimodal treatments, such as neural mobilisation. Little research has focused on identifying subgroups of patients who may show improvement following neural mobilisation. This study aimed to identify the variables that may influence response to nerve mobilisation in individuals with cervicobrachial pain.

Methods

A quasi-experimental prospective single-arm study was conducted with 50 participants. Data were collected on various potentially prognostic variables from baseline questionnaires, medical history and physical examination. Participants received 10 days of pain modulation treatment and nerve mobilisation exercises. The Neck Disability Index, Numeric Pain Rating Scale and Upper Limb Tension Test were performed before and after treatment to determine the effect of nerve mobilisation. Data were analysed using descriptive statistics, univariate correlation, multivariate stepwise logistic regression and non-parametric testing at α≤0.05.

Results

Four variables had a positive influence on treatment outcome: age <41 years, duration of symptoms ≤1 year, fasting blood glucose level ≤5.6 mmol/L (≤100 mg/dL) and systolic blood pressure ≤140 mmHg. On multiple linear regression, the presence of hypertension and diabetes were strongly associated with poor outcomes following nerve mobilisation.

Conclusions

Younger individuals with normal fasting blood glucose and systolic blood pressure who have had cervicobrachial pain for less than a year are more likely to benefit from pain modulation and neural mobilisation.

Sensory neuron cultures derived from adult db/db mice as a simplified model to study type-2 diabetes-associated axonal regeneration defects

Diabetic neuropathy (DN) is an early common complication of diabetes mellitus (DM), leading to chronic pain, sensory loss and muscle atrophy. Owing to its multifactorial etiology, neuron in vitro cultures have been proposed as simplified systems for DN studies. However, the most used models currently available do not recreate the chronic and systemic damage suffered by peripheral neurons of type-2 DM (T2DM) individuals. Here, we cultured neurons derived from dorsal root ganglia from 6-month-old diabetic db/db-mice, and evaluated their morphology by the Sholl method as an easy-to-analyze readout of neuronal function. We showed that neurons obtained from diabetic mice exhibited neuritic regeneration defects in basal culture conditions, compared to neurons from non-diabetic mice. Next, we evaluated the morphological response to common neuritogenic factors, including nerve growth factor NGF and Laminin-1 (also called Laminin-111). Neurons derived from diabetic mice exhibited reduced regenerative responses to these factors compared to neurons from non-diabetic mice. Finally, we analyzed the neuronal response to a putative DN therapy based on the secretome of mesenchymal stem cells (MSC). Neurons from diabetic mice treated with the MSC secretome displayed a significant improvement in neuritic regeneration, but still reduced when compared to neurons derived from non-diabetic mice. This in vitro model recapitulates many alterations observed in sensory neurons of T2DM individuals, suggesting the possibility of studying neuronal functions without the need of adding additional toxic factors to culture plates. This model may be useful for evaluating intrinsic neuronal responses in a cell-autonomous manner, and as a throughput screening for the pre-evaluation of new therapies for DN.

Summary: Morphological characterization of a model for evaluating neuritic regeneration in vitro in dorsal root ganglion primary neurons derived from type-2 diabetic mice with an advanced stage of diabetic neuropathy.

The Effects of Exercise on Cerebellar Growth-Associated Protein 43 and Adenylyl Cyclase- Associated Protein 1 Gene Expression and Proteins in Diabetic-Induced Neuropathy and Healthy Male Wistar Rats

BACKGROUND

The effect of exercise on the cerebellum cells in diabetic-induced neuropathy and healthy situations is not clear yet. Growth-associated protein 43 (GAP-43) and adenylyl cyclase-associated protein 1 (CAP-1) proteins can restore nerve cells. This study aimed to investigate the effect of aerobic exercise on GAP-43 and CAP-1 and their mRNA in the cerebellar tissue of diabetic-induced neuropathy and healthy Wistar rats.

METHODS

Around 40 healthy male Wistar rats with a mean weight of 271 ± 11.2 g were divided randomly into four groups; healthy aerobic exercise, diabetic-aerobic exercise, healthy-control, and diabetic-control. The exercise group performed aerobic exercise 5 days per week for 6 weeks.

RESULTS

Exercise increased CAP1 protein in the cerebellum tissue of healthy (P = 0.002) and diabetic (P = 0.002) groups compared with matched control groups. The effect of exercise on CAP1 was greater in diabetic compared with the healthy group (P = 0.002). The expression of CAP1 mRNA in the cerebellum was higher in the healthy exercise compared with the healthy control group (P = 0.002) and in the healthy exercise compared with the diabetic exercise group (P = 0.026). GAP43 protein was lower in the healthy exercise compared with the healthy control group (P = 0.002) while it was higher in diabetic exercise compared to the healthy exercise group (P = 0.002). Expression of GAP43 mRNA in the cerebellum was higher in the healthy (P = 0.002) and diabetic (P = 0.002) exercise groups compared to non-exercise matched groups and in the diabetic control group compared with the healthy control group (P = 0.002). Exercise improved latency in diabetic (P = 0.001) and healthy exercise groups (P = 0.02). No significant difference was found in blood glucose between exercise and control groups (P > 0.05).

CONCLUSION

Exercise improved cerebellar functions in healthy and diabetic rats, probably mediating by CAP1 protein, even without changing blood glucose.

Prevalence of painful diabetic peripheral neuropathy and its impact on quality of life among diabetic patients in Western region, Saudi Arabia

Background

Diabetic neuropathy is the most common long-term complications of diabetes, frequently presenting as painful diabetic peripheral neuropathy (PDPN), which can significantly impair patients' quality of life (QOL). This study set to estimate the prevalence of PNPD and health-related quality of life (HRQoL) in the setting of primary health care in Saudi Arabia.

Methods

This study was conducted in primary health-care centers affiliated with the National Guard Health Affairs in Western Saudi Arabia. Arabic version of the Douleur Neuropathique 4 questionnaire was administered on diabetic patients to screen for neuropathic pain and short-form 12 questionnaire to assess HRQoL.

Results

The study screened (n = 349) Type 2 diabetic patients. The prevalence of PDPN was 33.2%. PDRN was more likely to affect females (adjusted odds ratio ["AOR"] =1.96, P = 0.024), and those living with diabetes for over 15 years (AOR = 2.26, P = 0.039), and those on insulin treatment (AOR: 2.33, P = 0.010) alone or in combination (AOR = 1.78, P = 0.034). Both physical and mental components (MCs) of QOL scores were significantly higher in diabetic patients without PDPN compared to those with it; 49.57 ± 9.31 versus 40.77 ± 8.14 for physical component QOL and 51.72 ± 9.36 versus 44.35 ± 8.12 for MC QOL, P < 0.001.

Discussion and Conclusion

Painful peripheral neuropathy is relatively common among type 2 diabetic patients in Western Saudi Arabia and impacts both physical and MCs of the QOL of affected patients.

Progressive Muscle Relaxation and Mindfulness Meditation on Neuropathic Pain, Fatigue, and Quality of Life in Patients With Type 2 Diabetes: A Randomized Clinical Trial

PURPOSE

To examine the effects of progressive muscle relaxation and mindfulness meditation on the severity of diabetic peripheral neuropathic pain (DPNP), fatigue, and quality of life in patients with type 2 diabetes.

DESIGN

An assessor-blinded prospective randomized controlled trial.

METHODS

Participants were randomly assigned to the relaxation group (RG; n = 28), meditation group (MG; n = 25), or control group (CG; n = 24). The mean age of participants was 64.2 ± 8.1 years in the RG, 61.6 ± 8.0 years in the MG, and 64.1± 6.6 years in the CG. Patients in the intervention groups performed progressive muscle relaxation or mindfulness meditation at their home for 12 weeks, 20 min daily. The CG received only an attention-matched controlled education on pancreas anatomy and diabetes. Data collection was performed at baseline and at weeks 12 and 14 using the VAS, FACIT Fatigue Scale (FACIT-F), and Neuropathic Pain Impact on Quality of Life Questionnaire (NePIQoL).

FINDINGS

VAS scores were significantly lower in the RG and MG at week 12 (p < .05) and were statistically significant in the RG at week 14. Additionally, fatigue severity decreased significantly in the RG at weeks 12 and 14, compared to that in the CG (p < .05). While no significant difference was found in the quality of life scores between the study groups at weeks 12 and 14 (p > .05), a significant improvement in quality of life scores in the RG were provided at week 12 compared to those at baseline and week 14 (p < .05).

CONCLUSIONS

Both progressive muscle relaxation and mindfulness meditation had a positive impact on providing pain relief in patients with DPNP. Moreover, progressive muscle relaxation also appeared to have a beneficial effect on fatigue.

CLINICAL RELEVANCE

Based on the results, progressive muscle relaxation and mindfulness meditation can be recommended as supportive therapies for the management of DPNP.

Human adipose-derived mesenchymal stem cell-conditioned medium ameliorates polyneuropathy and foot ulceration in diabetic BKS db/db mice

BACKGROUND

Diabetic polyneuropathy (DPN) is the most common and early developing complication of diabetes mellitus, and the key contributor for foot ulcers development, with no specific therapies available. Different studies have shown that mesenchymal stem cell (MSC) administration is able to ameliorate DPN; however, limited cell survival and safety reasons hinder its transfer from bench to bedside. MSCs secrete a broad range of antioxidant, neuroprotective, angiogenic, and immunomodulatory factors (known as conditioned medium), which are all decreased in the peripheral nerves of diabetic patients. Furthermore, the abundance of these factors can be boosted in vitro by incubating MSCs with a preconditioning stimulus, enhancing their therapeutic efficacy. We hypothesize that systemic administration of conditioned medium derived from preconditioned MSCs could reverse DPN and prevent foot ulcer formation in a mouse model of type II diabetes mellitus.

METHODS

Diabetic BKS db/db mice were treated with systemic administration of conditioned medium derived from preconditioned human MSCs; conditioned medium derived from non-preconditioned MSCs or vehicle after behavioral signs of DPN was already present. Conditioned medium or vehicle administration was repeated every 2 weeks for a total of four administrations, and several functional and structural parameters characteristic of DPN were evaluated. Finally, a wound was made in the dorsal surface of both feet, and the kinetics of wound closure, re-epithelialization, angiogenesis, and cell proliferation were evaluated.

RESULTS

Our molecular, electrophysiological, and histological analysis demonstrated that the administration of conditioned medium derived from non-preconditioned MSCs or from preconditioned MSCs to diabetic BKS db/db mice strongly reverts the established DPN, improving thermal and mechanical sensitivity, restoring intraepidermal nerve fiber density, reducing neuron and Schwann cell apoptosis, improving angiogenesis, and reducing chronic inflammation of peripheral nerves. Furthermore, DPN reversion induced by conditioned medium administration enhances the wound healing process by accelerating wound closure, improving the re-epithelialization of the injured skin and increasing blood vessels in the wound bed in a skin injury model that mimics a foot ulcer.

CONCLUSIONS

Studies conducted indicate that MSC-conditioned medium administration could be a novel cell-free therapeutic approach to reverse the initial stages of DPN, avoiding the risk of lower limb amputation triggered by foot ulcer formation and accelerating the wound healing process in case it occurs.

Diabetic Polyneuropathy - Advances in Diagnosis and Intervention Strategies

Over half of people with diabetes mellitus develop diabetic polyneuropathy (DPN), which is a major cause of reduced quality of life due to disabling neuropathic pain, sensory loss, gait instability, fall-related injury, and foot ulceration and amputation. The latter represents a major health and economic burden, with lower limb amputation rates related to diabetes increasing in the UK. There is a need for early diagnosis of DPN so that early management strategies may be instigated, such as achieving tight glucose control and management of cardiovascular risk factors, in an attempt to slow its progression. To this end, a one-stop microvascular assessment involving a combined eye, foot and renal screening clinic has proven feasible in the UK. Unfortunately, there are currently no approved disease-modifying therapies for DPN. Some disease-modifying agents have demonstrated efficacy, but further large trials using appropriate clinical endpoints are required before these treatments can be routinely recommended. There has been emerging evidence highlighting a reduction in vitamin D levels in cases of painful DPN and the potential for vitamin D supplementation in deficient individuals to improve neuropathic pain; however, this needs to be proved in randomised clinical trials. The use of established agents for neuropathic pain in DPN is limited by poor efficacy and adverse effects, but patient stratification using methods such as pain phenotyping are being tested to determine whether this improves the outcomes of such agents in clinical studies. In addition, innovative approaches such as the topical 8% capsaicin patch, new methods of electrical stimulation and novel therapeutic targets such as NaV1.7 offer promise for the future. This article aims to discuss the challenges of diagnosing and managing DPN and to review current and emerging lifestyle interventions and therapeutic options.

In Vitro and In Vivo Effects of Flavonoids on Peripheral Neuropathic Pain

Neuropathic pain is a common symptom and is associated with an impaired quality of life. It is caused by the lesion or disease of the somatosensory system. Neuropathic pain syndromes can be subdivided into two categories: central and peripheral neuropathic pain. The present review highlights the peripheral neuropathic models, including spared nerve injury, spinal nerve ligation, partial sciatic nerve injury, diabetes-induced neuropathy, chemotherapy-induced neuropathy, chronic constriction injury, and related conditions. The drugs which are currently used to attenuate peripheral neuropathy, such as antidepressants, anticonvulsants, baclofen, and clonidine, are associated with adverse side effects. These negative side effects necessitate the investigation of alternative therapeutics for treating neuropathic pain conditions. Flavonoids have been reported to alleviate neuropathic pain in murine models. The present review elucidates that several flavonoids attenuate different peripheral neuropathic pain conditions at behavioral, electrophysiological, biochemical and molecular biological levels in different murine models. Therefore, the flavonoids hold future promise and can be effectively used in treating or mitigating peripheral neuropathic conditions. Thus, future studies should focus on the structure-activity relationships among different categories of flavonoids and develop therapeutic products that enhance their antineuropathic effects.

A systematic review on the efficacy of vitamin D supplementation on diabetic peripheral neuropathy

BACKGROUND & AIMS

Vitamin D deficiency is known to be prevalent in patients with diabetes and in particular in those having symptoms of diabetic peripheral neuropathy (DN). Thus, it is worthy to investigate whether a supplementation of vitamin D would improve pain among those having diabetes and DN.

METHODS

A systematic literature search was performed to identify studies that reported the impact of vitamin D supplementation on the signs and symptoms of DN. Random effect models were used to meta-analyze effect sizes. Quality assessment was also performed.

RESULTS

Four studies including 364 patients met the inclusion criteria. Meta-analytical results were as follows: Serum Vitamin D level change of 1.39 (95% CI = 1.220 to 1.573, p = 0.008), HbA1c change of 0.134 (95% CI = -0.153 to 0.418, p = 0.3), McGill Pain Questionnaire score of 1.14 (95% CI = 1.222 to 1.672, p < 0.0001), all in favor of the vitamin D supplementation group. Non-meta-analytical results of all individual studies showed significant amelioration of pain scores. One study reported no significant change in nerve conduction study. Pain improvement was not correlated to baseline or change in serum vitamin D level.

CONCLUSION

Vitamin D supplementation could be an added value in the treatment of painful peripheral diabetic neuropathy. Amelioration in pain might be related to the absolute value of vitamin D attained following supplementation. The findings of this review are promising and further research with large sample randomized trials is warranted.

Glucose time in range and peripheral neuropathy in type 2 diabetes mellitus and chronic kidney disease

​OBJECTIVE: Compared with hemoglobin A1c (HbA1c), continuous glucose monitoring (CGM) may better capture risk of diabetes complications in patients with chronic kidney disease (CKD), including diabetic peripheral neuropathy (DPN). We hypothesized that glucose time in range (TIR), measured by CGM, is associated with DPN symptoms among participants with type 2 diabetes mellitus (type 2 DM) and moderate-to-severe CKD. ​RESEARCH DESIGN AND METHODS: We enrolled 105 people with type 2 DM treated with insulin or sulfonylurea, 81 participants with CKD (estimated glomerular filtration rate (eGFR) <60 mL/min/1.73 m²) and 24 matched control participants with eGFR ≥60 mL/min/1.73 m². Each participant wore a CGM for two 6-day periods. Calculated glycemic measures included TIR (glucose 70-180 mg/dL) and glucose management indicator (GMI). DPN symptoms were assessed using the Michigan Neuropathy Screening Instrument (MNSI) questionnaire, with a positive MNSI score defined as ≥2 symptoms. ​RESULTS: Participants with CKD had a mean age of 68 years, diabetes duration 20 years, eGFR 38 mL/min/1.73 m² and HbA1c 7.8%, 61 mmol/mol. Sixty-two participants reported ≥2 DPN symptoms, 51 (63%) with CKD and 11 (46%) controls. Less TIR and higher GMI were associated with higher risk of MNSI questionnaire score ≥2 (OR 1.25 (95% CI 1.02 to 1.52) per 10% lower TIR, and OR 1.79 (95% CI 1.05 to 3.04) per 1% higher GMI, adjusting for age, gender and race). Similar results were observed when analyses were restricted to participants with CKD. In contrast, there was no significant association of HbA1c with DPN symptoms. ​CONCLUSIONS: Symptoms of DPN were common among participants with long-standing type 2 DM and CKD. Lower TIR and higher GMI were associated with DPN symptoms.

Whole body vibration showed beneficial effect on pain, balance measures and quality of life in painful diabetic peripheral neuropathy: a randomized controlled trial

Purpose

The aim of the study was to determine the efficacy of whole body vibration (WBV) therapy on pain, neuropathy disability score, balance, proprioception and quality of life (QOL) in patients with painful diabetic peripheral neuropathy (PDPN).

Methods

Twenty-six (16 males and 10 females) patients with PDPN were selected on the basis of inclusion and exclusion criteria. Subjects were randomly allocated to an experimental group (n = 13, age = 60.69 ± 5.08) and a control group (n = 13, age = 59.54 ± 4.25). The experimental group was given WBV therapy for six weeks (3 days/week) in addition to standard medical care, dietary advice and lifestyle modifications. Control group was provided only standard medical care, dietary advice and lifestyle modifications. Outcome measures included numeric pain rating scale (NPRS), Leeds assessment of neuropathic symptoms and signs (LANSS), vibration perception threshold (VPT), neuropathy disability score (NDS), proprioception, single-leg stance test (SLST), timed up and go test (TUGT) and short form 36 questionnaire (SF-36).

Results

NPRS, LANSS, NDS, SLST and TUGT showed significant time effect (p ≤ 0.022) and time×group interaction (p ≤ 0.007), whereas group effect was found to be significant only in LANSS (p = 0.001). VPT showed significant group effect (p ≤ 0.045) and time×group interaction (p ≤ 0.007) at great toe, metatarsal head and total average score. SF-36 was found to be significant time effect (p ≤ 0.024) in all domains except limitations due to physical health (p = 0.461). SF-36 average score was found be significant for group effect (p = 0.002) and time×group interaction (p < 0.001).

Conclusion

WBV improves sensory sensations like pain and vibration perception, neuropathy disability score, balance measures and health-related QOL in PDPN.

Role of Protein Kinase C in Diabetic Complications

Diabetes is the most common and systemic disorder associated with hyperglycemia which is the significant factor in the development of micro- and macrovascular changes. Many mechanistic approaches i.e. activation of Protein kinase C, glycation end products production, hexosamine pathway and polyol pathway induce cellular damage and lead to the development of diabetic complications like nephropathy, neuropathy, retinopathy, and myopathy. One of the adverse effects of long-lasting hyperglycemia is activation of PKC (intracellular signaling enzyme) and has become a field of great research interest. Hence, in this review special emphasis is placed on microvascular complications which are due to activation of PKC. Clinical trials have also been conducted using selective PKC inhibitors and have shown positive results against hyperglycemia.

The relationship between serum 25-hydroxyvitamin D concentration and type 2 diabetic peripheral neuropathy: A systematic review and a meta-analysis

BACKGROUND

Vitamin D is a fat-soluble vitamin that is related to the health of the human body and is an indispensable nutrient for human beings. Some studies indicated that type 2 diabetes mellitus (T2DM) with diabetic peripheral neuropathy (DPN) may be associated with vitamin D deficiency, but the current understanding of this point of view remains controversial. This study aimed to evaluate the correlation between serum 25-hydroxyl vitamin D (25 [OH] D) concentration and DPN in patients with T2DM by a meta-analysis, and to provide a reference for doctors.

METHODS

Relevant studies were selected from the PubMed, Cochrane Library, China National Knowledge Infrastructure, VIP databases, and Wanfang Data Knowledge Service Platform databases dating from 2000 to December 2017. A total of 75 articles related to serum 25 (OH) D and DPN were selected from 2000 to December 2017. Based on the inclusion and exclusion criteria of the literature, a quality assessment was conducted using the Newcastle-Ottawa scale, and a meta-analysis was performed by RevMan5.3 statistical software.

RESULTS

Thirteen studies that involved a total of 2814 type 2 diabetic patients were finally included into the meta-analysis. Meta-analysis results, heterogeneity test showed that, P < .000 01, I = 92%, calculation by random effect model revealed that, the serum concentration of 25 (OH) D in T2DM combined with DPN group was lower than that in the group without DPN (weighted mean difference = -0.74, 95% confidence interval: -1.03 to -0.46) CONCLUSIONS:: Vitamin D is associated with type 2 DPN (DPN), and vitamin D deficiency can lead to an increased risk of type 2 DPN. However, more high-quality research is needed.

Skin Autofluorescence Is Associated with Diabetic Peripheral Neuropathy in Chinese Patients with Type 2 Diabetes: A Cross-Sectional Study

Background: Diabetic peripheral neuropathy (DPN) affects nearly 50% of the diabetic population. Advanced glycation end products, measured through skin autofluorescence (SAF), play an important role in the diagnosis and prevention of DPN. To date, however, no relevant study has discussed the relationship between SAF and the Chinese population. Objective: We conducted this study to evaluate the association between DPN and SAF among the Chinese population. Methods: In this cross-sectional study, we recruited a total of 820 patients with type 2 diabetes. All of the patients underwent SAF measurements and a nerve conduction study (NCS). Post-SAF characterization, the patients were divided into three groups according to the first and third quartiles of their SAF values (AU) (SAF ≤ 2.2; 2.2 < SAF ≤ 2.7; SAF > 2.7). Based on the results of the NCS, patients were divided into two groups: DPN and non-DPN. Results: When compared with the non-DPN group (n = 275) with the DNP group. The latter had higher SAF values (2.72 ± 0.55 AU vs. 2.17 ± 0.71 AU, P < 0.01). There were significant differences in age, the percentage of DPN, and NCS parameters, including motor nerve conduction velocity, sensory nerve conduction velocity, distal latency, and sensory nerve action potential among the three SAF groups (p < 0.05). The SAF value was positively associated with DPN (r = 0.11, p < 0.01). After adjusting for all potential confounders, the SAF values were still associated with an increased risk of DPN (odds ratio 5.15; 95% confidence interval [1.48-4.53]) (p < 0.01). A receiver operating characteristic analysis indicated that an SAF value >2.57 ng/mL predicts a threefold increased risk of DPN (p < 0.01). Conclusions: SAF is an independent risk factor for DPN, which might be of potential value for screening DPN in Chinese patients with type 2 diabetes.

A comparative double-blind randomized study on the effectiveness of Duloxetine and Gabapentin on painful diabetic peripheral polyneuropathy

Background: The most common cause of polyneuropathy is diabetes mellitus. Neuropathic pain is seen in 26% of diabetic population. Therapeutic techniques for this disease can become challenging. Method: This study was a prospective comparative double-blind randomized study which was conducted during an eight-week period. Totally, 104 painful diabetic peripheral polyneuropathy (PDPP) patients who had a minimum Visual Analog Scale (VAS) of 40 millimeters, received no pain-controlling medication, and had no other severe disease at its final stage were randomly assigned to two groups (n=52) through the four block method. One group received Duloxetine and the other received Gabapentin. The effectiveness was measured through primary effectiveness (VAS scale) and secondary effectiveness (Sleep Interference Score, and Clinical Global Impression of Change (CGIC)). Medication compliance was assessed by enumerating the number of patients who refused treatment because of side effects. The Fisher's exact T-test and ANOVA were used for data analysis. This study was approved by the Ethics Committee of Jundishapur, University of Medical sciences Ahvaz, Iran, under reference number: IR.AJUMS.REC.1395.78. In addition, this study was registered and approved in the Iranian Registry of Clinical Trials (IRCT ID: IRCT20161023030455N2) (http://irct.ir/). Results: VAS, Sleep Interference Score, and CGIC were significantly improved (P<0.05) through time in both groups, [For GBP: VAS^Baseline=64±20.03, VAS^week1=55.32±18.76, VAS^week4=44.68±15.82, VAS^week8=39.43±14.32; For DLX: VAS^Base-line=62±21.18, VAS^week1=58.76±20.37, VAS^week4=45.84±16.21, VAS^week8=36.78±15.62] while a significant difference between the two groups was not observed (P<0.05). However, such significant improvements were not observed in the Duloxetine group at the end of the first week (P=674). Improvement in Sleep Interference Score and CGIC were similar to the results for the VAS scale. Side effects in the Duloxetine group (n=2) compared to the Gabapentin group (n=9) were significantly less (P<0.001). As a result, medication acceptance in the Duloxetine group (n=47) was significantly better than the Gabapentin (n=41) group (P<0.001). Conclusion: Both Duloxetine and Gabapentin are effective for the treatment of PDPP. On the one hand, Gabapentin shows the effect earlier while has more side effects. Conversely, Duloxetine has better medication compliance. Trial registration: The method of this study was approved by the Ethics Committee of Jundishapur University of Medical Sciences, Ahvaz, Iran, under reference number: IR.AJUMS.REC.1395.78. In addition, this study was registered and approved in the Iranian Registry of Clinical Trials (IRCT ID: IRCT20161023030455N2) (http://irct.ir/).

The risk factors for diabetic peripheral neuropathy: A meta-analysis

Diabetic peripheral neuropathy (DPN), the most common chronic complication of diabetes, has become an important public health crisis worldwide. Given that DPN is extremely difficult to treat, determining its risk factors and controlling it at an early stage is critical to preventing its serious consequences and the burden of social disease. Current studies suggest that the risk factors for diabetic peripheral neuropathy are the duration of diabetes, age, glycosylated hemoglobin A1c (HbA1c), diabetic retinopathy (DR), smoking, and body mass Index (BMI). However, most of the aforementioned studies are cross-sectional, and the sample sizes are very limited, so the strength of causal reasoning is relatively low. The current study systematically evaluated DPN’s influencing factors in patients with type 2 diabetes using evidence-based medicine. Overall, 16 included studies (14 cross-sectional studies and 2 case-control studies including 12,116 cases) that conformed to the present criteria were included in the final analysis. The results suggested that the duration of diabetes (MD 2.5, 95% CI 1.71~3.29), age (MD 4.00, 95% CI 3.05~4.95), HbA1c (MD 0.48, 95% CI 0.33~0.64), and DR (OR 2.34, 95% CI 1.74~3.16) are associated with significantly increased risks of DPN among diabetic patients, while BMI, smoking, total triglyceride (TG), and total cholesterol (TC) did not indicate any risks of increasing DPN. The findings provide a scientific basis for a further understanding of the causes of type 2 diabetes complicated with peripheral neuropathy and the improvement of preventive strategies. The next step is to conduct further high-quality prospective cohort studies to validate this paper’s findings.

Characteristics of patients with neuropathic pain syndromes screened by the painDETECT questionnaire and diagnosed by physician exam

Background

The aim of this study was to identify the clinical characteristics, treatment usage, and health outcomes of US adults diagnosed with neuropathic pain (NeP) by experienced physicians.

Methods

Adults with scores exceeding the threshold for probable NeP (painDETECT ≥19) and diagnosed with NeP by a qualified physician completed a questionnaire that included comorbid conditions, pain symptoms and experiences, medication use, health status (3-level EuroQol 5 Dimensions (EQ-5D-3L]: health utilities index and visual analog scale), pain severity and interference with functioning (Brief Pain Inventory), and work and activity impairment (Work Productivity and Activity Impairment questionnaire). Descriptive analyses were performed for each NeP subtype.

Results

Participants (n=295) were predominantly female (64.4%), middle-aged (53.9%), and white (51.5%). Chronic low back pain was the most frequently diagnosed major NeP syndrome (n=166), followed by diabetic peripheral neuropathy (n=58), post-trauma neuropathy (n=47), post-surgical neuropathy (n=28), and central NeP (n=23). An additional 45 participants were diagnosed, but did not meet the criteria for the aforementioned subtypes. Participants could be diagnosed with multiple subtypes. Across each NeP subtype, patients reported high rates of comorbid disease, including arthritis (range: 39.1%–64.3%) and high blood pressure (range: 26.1%–69.0%), as well as symptomology that included numbness (range: 68.1%–91.4%) and changes in muscular strength (range: 24.1%–65.2%). The majority of patients reported back pain (range: 77.8%–95.7%) and arthritis/joint pain (range: 68.1%–78.6%). The most commonly reported types of NeP pain medication were non-steroidal anti-inflammatory drugs (range: 43.1%–70.2%), weak opioids (range: 22.2%–39.3%), and strong opioids (range: 8.7%–28.6%). All six NeP groups generally reported similar levels of dysfunction on all self-report measures. The most notable finding was that the EuroQol-5D-3L health utilities index scores for each of the six groups were lower than the US norms by a clinically important amount.

Conclusion

These exploratory findings indicate that patients with NeP across different etiologies are medically complex and experience impaired function across multiple domains.

Dose vitamin D supplementations improve peripheral diabetic neuropathy? A before-after clinical trial

OBJECTIVE

Peripheral neuropathy is a common complication of diabetes mellitus. This study was set to assess the effect of vitamin D supplementation on peripheral neuropathy in patients with type 2 diabetes (T2DM).

MATERIALS AND METHODS

This study was a quasi-experimental trial in Yazd diabetic research center. Sixty T2DM subjects (30-65 years old) with painful diabetic neuropathy enrolled in this study from March 2017 till April 2018. Patients received weekly 50000 IU of vitamin D3 for 12 weeks orally. Evaluation of diabetic neuropathy was performed by using Michigan Neuropathy Screening Instrument (MNSI) before and after trial. Also fasting plasma glucose, HbA1c, calcium and vitamin D checked before and after the trial. SPSS version 20 software was used for statistical analysis. P ≤ 0.05 was considered to be statistically significant.

RESULTS

Among 60 T2DM patients, 58 completed the study. Most of them (53.4%) were male. At the end of study, HbA1c, vitamin D, MNSI (both questionnaire and physical examination) improved that is statistically significant (p-value: <0.001).

CONCLUSION

Oral supplementation of vitamin D 3 (50,000 IU) once weekly for 12 weeks was associated with improvement in the serum level of vitamin D and significant decrease in the symptoms and sign of diabetic neuropathy. So serum vitamin D level should be checked in persons with diabetic neuropathy and low levels of it should be corrected in order to reducing neuropathy severity.

Glial-derived neurotrophic factor is essential for blood-nerve barrier functional recovery in an experimental murine model of traumatic peripheral neuropathy

There is emerging evidence that glial-derived neurotrophic factor (GDNF) is a potent inducer of restrictive barrier function in tight junction-forming microvascular endothelium and epithelium, including the human blood-nerve barrier (BNB) in vitro. We sought to determine the role of GDNF in restoring BNB function in vivo by evaluating sciatic nerve horseradish peroxidase (HRP) permeability in tamoxifen-inducible GDNF conditional knockout (CKO) adult mice following non-transecting crush injury via electron microscopy, with appropriate wildtype (WT) and heterozygous (HET) littermate controls. A total of 24 age-, genotype- and sex-matched mice >12 weeks of age were injected with 30 mg/kg HRP via tail vein injection 7 or 14 days following unilateral sciatic nerve crush, and both sciatic nerves were harvested 30 minutes later for morphometric assessment by light and electron microscopy. The number and percentage of HRP-permeable endoneurial microvessels were ascertained to determine the effect of GDNF in restoring barrier function in vivo. Following sciatic nerve crush, there was significant upregulation in GDNF protein expression in WT and HET mice that was abrogated in CKO mice. GDNF significantly restored sciatic nerve BNB HRP impermeability to near normal levels by day 7, with complete restoration seen by day 14 in WT and HET mice. A significant recovery lag was observed in CKO mice. This effect was independent on VE-Cadherin or claudin-5 expression on endoneurial microvessels. These results imply an important role of GDNF in restoring restrictive BNB function in vivo, suggesting a potential strategy to re-establish the restrictive endoneurial microenvironment following traumatic peripheral neuropathies.

An Assessment of Clinically Important Differences on the Worst Pain Severity Item of the Modified Brief Pain Inventory in Patients with Diabetic Peripheral Neuropathic Pain

Objectives

Using patient global impression of change (PGIC) as an anchor, an approximately 30% reduction on an 11-point numeric pain intensity rating scale (PI-NRS) is considered a clinically important difference (CID) in pain. Our objective was to define the CID for another pain measure, the worst pain severity (WPS) item of the modified Brief Pain Inventory (m-BPI).

Methods

In this post hoc analysis of a double-blind, placebo-controlled, phase 2 study, 452 randomized patients with diabetic peripheral neuropathic pain (DPNP) were followed over 5 weeks, with m-BPI data collected weekly and PGIC at treatment conclusion. Receiver operating characteristic (ROC) curves (via logistic regression) were used to determine the changes in the m-BPI-WPS score that best predicted ordinal clinical improvement thresholds (i.e., "minimally improved" or better) on the PGIC.

Results

Similar to the PI-NRS, a change of -3 (raw) or -33.3% from the baseline on the m-BPI-WPS optimized prediction for the "much improved" or better PGIC threshold and represents a CID. There was a high correspondence between observed and predicted PGIC categories at each PGIC threshold (ROC AUCs were 0.78-0.82).

Conclusions

Worst pain on the m-BPI may be used to assess clinically important improvements in DPNP studies. Findings require validation in larger studies.