Painful diabetic peripheral neuropathy: Role of oxidative stress and central sensitisation

Impact of Impaired Fasting Glucose on Musculoskeletal Pain Among Female-Dominated Healthcare Workers

Introduction: In 2021, 10.5% of people aged 20-79 had diabetes, projected to rise to 12.2% by 2045, causing early deaths and straining healthcare systems. Musculoskeletal (MS) pain is common, affecting many workers and the general population. Prediabetes, notably impaired fasting glucose (IFG), is linked to increased MS pain risk. Objective: This study aims to assess IFG's impact on MS pain and specific pain sites to aid prevention strategies. Methods: This cross-sectional study used the '2023 Employee Occupational Safety and Health Management Database' from a Taichung hospital. It included health checks, demographics, living and work data, and MS pain surveys. Out of 2369 staff members contacted, 1039 valid responses were analyzed, excluding incomplete data, diabetes history, or fasting blood glucose levels above 125 mg/dL. Data on sex, age, marital status, coffee and alcohol consumption, sleep duration, exercise habits, height, weight, chronic diseases, profession, work hours, shift work, and education level were collected. Fasting blood glucose was verified using American Diabetes Association criteria (100-125 mg/dL). The Nordic Musculoskeletal Questionnaire (NMQ) measured MS pain frequency and severity, creating a pain degree index. Results: Overall, 21.17% had IFG. Participants were mostly female (85.18%), averaging 37.50 years. Neck and shoulder pain risk was linked to sex, coffee and alcohol consumption, sleep, exercise, chronic diseases, work hours, and IFG. Ankle pain risk was linked to coffee and alcohol consumption. IFG, coffee, alcohol, sleep under 6 h, chronic diseases, and work hours were independent risk factors for neck and shoulder pain. IFG was a risk factor for those without overweight or obesity. A mediation model tested IFG's indirect effect on neck and shoulder pain among overweight or obese individuals, showing that IFG mediates the relationship between being overweight or obese and increased neck and shoulder pain risk. Conclusions: Among female-dominated healthcare workers, IFG, daily coffee, recent alcohol consumption, less than 6 h of sleep, chronic diseases (excluding diabetes), and longer work hours are independent risk factors for neck and shoulder pain. IFG mainly affects these areas, increasing pain risk regardless of body weight. Healthy blood glucose levels are associated with a lack of musculoskeletal pain, suggesting a novel prevention approach needing further study.

The role of activated partial thrombin time in mediating the impact of poorly glycemic control on diabetic peripheral neuropathy in patients with type 2 diabetes mellitus

Aim

This study aims to investigate the role of activated partial thrombin time (APTT) as a potential mediator in the relationship between suboptimal glycemic control and diabetic peripheral neuropathy (DPN) in individuals with type 2 diabetes mellitus (T2DM).

Methods

A total of 183 T2DM patients were enrolled in this study. Comprehensive clinical data, including coagulation parameters and nerve conduction velocity, were collected and compared between patients with and without DPN. Subsequent correlation and regression analyses were conducted to explore the associations among APTT, HbA1c levels, and nerve conduction velocities. Moreover, mediation analyses were performed to evaluate the total, direct, and indirect effects of HbA1c on specific nerve conduction velocities, with APTT serving as a mediator.

Results

In comparison to 101 patients without DPN, 82 patients with DPN exhibited significantly elevated levels of HbA1c and decreased levels of APTT. Notably, levels of APTT and HbA1c were correlated with conduction velocities of Tibial nerve motor fibers, as well as sensory fibers of the Ulnar nerve, Median nerve, and Sural nerve. Furthermore, both elevated HbA1c and decreased APTT were identified as risk factors for DPN in T2DM individuals. Mediation analysis showed that APTT mediated the indirect effect of HbA1c on the conduction velocities of sensory fibers in both the ulnar nerve and sural nerve (95% CI: -0.3448, -0.0135; -0.3523, -0.0180). APTT mediated the relationship between HbA1c and the conduction velocities of sensory fibers in the ulnar nerve or sural nerve by 34.66% or 22.03%, respectively.

Conclusions

In patients with T2DM, uncontrolled HbA1c and shorter APTT emerges as risk factors for DPN. Additionally, the effect of increased HbA1c upon DPN, especially for influenced conduction velocities of sensory fibers in both the ulnar nerve and sural nerve may partly medicated by decreased APTT.

Postprandial glycaemic response and pain sensitivity in breast cancer survivors suffering from chronic pain: a double-blind, randomised controlled cross-over pilot experiment

INTRODUCTION

The study's primary goal is to investigate differences in postprandial glycaemic response (PPGR) to beverages with varying glycaemic index (i.e. low and medium) between breast cancer survivors (BCS) with chronic pain and healthy pain-free controls (HC). The secondary goal of the study is to investigate the potential link between PPGR and pain-related outcomes in BCS with chronic pain.

METHODS

In this study, 15 BCS and 15 HC were included. After 12 h of fasting, subjects were randomised between drinking a beverage made with 50 g of sucrose (medium) or isomaltulose (low) within 250 ml water. Blood glucose levels were monitored at fasting as well as at 15, 30, 45, 60, 90 and 120 min following beverage consumption. Furthermore, each participant was evaluated using several experimental pain measurements, including pressure pain thresholds (PPT), electrical detection threshold, electrical pain threshold, temporal summation and electrical offset analgesia (OA).

RESULTS

The BCS group had significantly higher PPGR to sucrose (p = .001) than the HC group. Furthermore, when PPGR to sucrose was compared to PPGR to isomaltulose within the groups, the BCS group showed a considerably larger difference (p = .012). Additionally, correlation analyses indicated both positive and negative associations between PPGR after sucrose intake and specific pain measurements (PPT-tibialis (r = .599), OA (rs = - .549), respectively) in BCS, and a positive association between the difference in PPGR between sucrose and isomaltulose and PPT-tibialis (r = .622).

CONCLUSION

These findings suggest that medium glycaemic index beverage intakes result in significantly higher blood glucose responses (i.e. PPGR) than low-glycaemic index beverage intakes in BCS. Additionally, BCS show an impaired glycaemic response to medium glycaemic index beverage intake and that the impaired glycaemic response might be related to pain sensitivity and endogenous analgesia in BCS. Furthermore, the higher glycaemic response to sucrose and greater difference in the amount of change in PPGR (when isomaltulose was substituted for sucrose) compared to HC highlight the importance of understanding how dietary choices with a lower glycaemic index can alter glycaemic regulation in BCS with chronic pain.

Diabetic small fiber neuropathy: clinical and electrophysiological study

Background

Diabetic neuropathy is diagnosed late due to lack of easy and readily available biomarkers; early identification can prompt proper interventions before the irreversible large fiber damage. The aim of this study is to assess small fiber dysfunction using cutaneous silent period (CSP) and sympathetic skin response (SSR) tests in patients with diabetic small fiber neuropathy (SFN) and compare results with clinical, neuropathy severity and quality of life measures. A total of 45 subjects were classified into: Group I: diabetic patients with pure SFN, group II: diabetic patients with mixed fiber neuropathy, and group III: healthy subjects. All underwent evaluation by anthropometric, clinical and quality of life measures, electrophysiological evaluation by CSP and SSR and distal leg skin biopsy.

Results

Age and gender distribution did not significantly differ between the studied groups. Both patients’ groups showed comparable poor quality of life in relation to healthy subjects. CSP onset latencies and SSR amplitudes significantly correlated with studied clinical and severity measures, but neither correlate with each other in diabetic pure SFN patients. Both CSP and SSR measures were specific in diagnosing diabetic pure SFN, but mostly with poor sensitivity. Combining sensitivities of different CSP and SSR measures improved the overall sensitivity to early screen for SFN in diabetic patients.

Conclusions

Both CSP and SSR may have the potential to early detect diabetic pure SFN. Suspected diabetic patients with SFN should be separately screened for both somatosensory and sudomotor/autonomic affection.

Challenging directions in pediatric diabetes - the place of oxidative stress and antioxidants in systemic decline

Diabetes is a complex condition with a rising global incidence, and its impact is equally evident in pediatric practice. Regardless of whether we are dealing with type 1 or type 2 diabetes, the development of complications following the onset of the disease is inevitable. Consequently, contemporary medicine must concentrate on understanding the pathophysiological mechanisms driving systemic decline and on finding ways to address them. We are particularly interested in the effects of oxidative stress on target cells and organs, such as pancreatic islets, the retina, kidneys, and the neurological or cardiovascular systems. Our goal is to explore, using the latest data from international scientific databases, the relationship between oxidative stress and the development or persistence of systemic damage associated with diabetes in children. Additionally, we highlight the beneficial roles of antioxidants such as vitamins, minerals, polyphenols, and other bioactive molecules; in mitigating the pathogenic cascade, detailing how they intervene and their bioactive properties. As a result, our study provides a comprehensive exploration of the key aspects of the oxidative stress-antioxidants-pediatric diabetes triad, expanding understanding of their significance in various systemic diseases.

The Role of Insulin Within the Socio-Psycho-Biological Framework in Type 2 Diabetes-A Perspective from Psychoneuroimmunology

The interplay between socio-psychological factors and biological systems is pivotal in defining human health and disease, particularly in chronic non-communicable diseases. Recent advancements in psychoneuroimmunology and mitochondrial psychobiology have emphasized the significance of psychological factors as critical determinants of disease onset, progression, recurrence, and severity. These insights align with evolutionary biology, psychology, and psychiatry, highlighting the inherent social nature of humans. This study proposes a theory that expands insulin's role beyond traditional metabolic functions, incorporating it into the Mitochondrial Information Processing System (MIPS) and exploring it from an evolutionary medicine perspective to explore its function in processing psychological and social factors into biological responses. This narrative review comprises data from preclinical animal studies, longitudinal cohort studies, cross-sectional studies, machine learning analyses, and randomized controlled trials, and investigates the role of insulin in health and disease. The result is a proposal for a theoretical framework of insulin as a social substance within the socio-psycho-biological framework, emphasizing its extensive roles in health and disease. Type 2 Diabetes Mellitus (T2DM) with musculoskeletal disorders and neurodegeneration exemplifies this narrative. We suggest further research towards a comprehensive treatment protocol meeting evolutionary expectations, where incorporating psychosocial interventions plays an essential role. By supporting the concept of 'insulin resilience' and suggesting the use of heart rate variability to assess insulin resilience, we aim to provide an integrative approach to managing insulin levels and monitoring the effectiveness of interventions. This integrative strategy addresses broader socio-psychological factors, ultimately improving health outcomes for individuals with T2DM and musculoskeletal complications and neurodegeneration while providing new insights into the interplay between socio-psychological factors and biological systems in chronic diseases.

Exploration and identification of diabetes targets in nursing: CDH1 and DVL1

Diabetes is a chronic disease caused by absolute or relative insufficiency of insulin secretion and impaired insulin utilization. CDH1 and DVL1 role in diabetes and its nursing care is unclear. The diabetes dataset GSE21321 and GSE19790 profiles were downloaded from the gene expression omnibus (GEO) database. Perform differentially expressed genes (DEGs) screening, weighted gene co-expression network analysis (WGCNA), protein-protein interaction (PPI) network construction and analysis, functional enrichment analysis, gene set enrichment analysis (GSEA), immune infiltration analysis, and Comparative Toxicogenomics Database (CTD) analysis. Gene expression heat map was drawn. TargetScan was used to screen the miRNA that regulates central DEGs. 1983 DEGs were obtained. According to Gene Ontology (GO) analysis, they were mainly enriched in signal regulation, catenin complexes, and signal receptor binding. In Kyoto Encyclopedia of Gene and Genome (KEGG) analysis, they were mainly concentrated in the Rap1 signaling pathway, cAMP signaling pathway, and Hippo signaling pathway. The DEGs are mainly enriched in cell signaling, Wnt signaling vesicles, growth factor activity, and the interaction between neural active ligands and receptors. In the enrichment project of Metascape, BMP signaling pathways and cell population proliferation can be seen in the GO enrichment project. The soft threshold power in WGCNA is set to 5. A total of 15 modules were generated. Core gene expression heatmap showed that core genes (CTNNB1, CDH1, DVL1) were highly expressed in diabetes samples. CTD analysis showed thatCTNNB1, CDH1, DVL1were associated with weight gain, inflammation, and necrosis. CDH1 and DVL1 are highly expressed in diabetes and may become molecular targets for diabetes and its care.

Unravelling relationships between obesity, diabetes, and factors related to somatosensory functioning in knee osteoarthritis patients

OBJECTIVE

This study explores the association between obesity, diabetes, and somatosensory functioning in patients with knee osteoarthritis (OA), aiming to understand how metabolic conditions are related to pain mechanisms in this patient population. We hypothesized that higher body mass index (BMI), fat mass, and glycated hemoglobin levels (HbA1c) are associated with signs of altered somatosensory functioning.

METHODS

A cross-sectional analysis was conducted as part of a larger multicentre prospective cohort study. Data were collected from patients awaiting total knee arthroplasty in Belgium and the Netherlands. Associations between BMI, fat mass, HbA1c, and various pain-related variables were examined employing Pearson and Spearman correlation analyses which were further analyzed with linear regression techniques.

RESULTS

The study included 223 participants. Analysis revealed a significant although weak negative correlation between fat mass and pressure pain thresholds (PPT) at multiple locations, suggesting a link between higher fat mass and increased mechanical hyperalgesia. There were no significant correlations between BMI and pain-related outcomes. HbA1c levels showed very weak positive correlations with pain measures but did not withstand correction for multiple testing.

CONCLUSION

The findings indicate that fat mass may be closely associated with altered somatosensory functioning in patients with knee OA. However, no significant correlations were found between BMI or HbA1c levels and pain-related outcomes. Future research should focus on longitudinal studies to elucidate the causal relationships and further explore the impact of metabolic factors on pain mechanisms in this patient population. Key Points • The findings indicate that fat mass may be closely associated with altered somatosensory functioning in patients with knee OA.

Surgery for carpal tunnel syndrome in patients with and without diabetes-Is there a difference in the frequency of surgical procedures?

Carpal tunnel syndrome (CTS) occurs more often among individuals with diabetes. The aim of this retrospective observational registry study was to examine whether individuals with diabetes and CTS are treated surgically to the same extent as individuals with CTS but without diabetes. Data on CTS diagnosis and surgery were collected from the Skåne Healthcare Register (SHR). A total of 35,105 individuals (age ≥ 18 years) diagnosed with CTS from 2004-2019 were included. Data were matched to the Swedish National Diabetes Register (NDR. Cox regression models were used to calculate the risk of the use of surgical treatment. Of the 35,105 included individuals with a CTS diagnosis, 17,662 (50%) were treated surgically, and 4,966 (14%) had diabetes. A higher number of individuals with diabetes were treated surgically (2,935/4,966, 59%) than individuals without diabetes (14,727/30,139, 49%). In the Cox regression model, diabetes remained a significant risk factor for surgical treatment (PR 1.14 (95% CI 1.11-1.17)). Individuals with type 1 diabetes were more frequently treated surgically (490/757, 65%) than individuals with type 2 diabetes (2,445/4,209, 58%). There was no difference between the sexes and their treatment. The duration of diabetes was also a risk factor for surgical treatment in diabetes type 2, but high HbA1c levels were not. Individuals with diabetes are more likely to be treated surgically for CTS than individuals without diabetes. Individuals with type 1 diabetes are more likely to be treated surgically for CTS than individuals with type 2 diabetes.

Ginger alleviates mechanical hypersensitivity and anxio-depressive behavior in rats with diabetic neuropathy through beneficial actions on gut microbiome composition, mitochondria, and neuroimmune cells of colon and spinal cord

The relationship among gut microbiota, mitochondrial dysfunction/neuroinflammation, and diabetic neuropathic pain (DNP) has received increased attention. Ginger has antidiabetic and analgesic effects because of its anti-inflammatory property. We examined the effects of gingerols-enriched ginger (GEG) supplementation on pain-associated behaviors, gut microbiome composition, and mitochondrial function and neuroinflammation of colon and spinal cord in DNP rats. Thirty-three male rats were randomly divided into 3 groups: control group, DNP group (high-fat diet plus single dose of streptozotocin at 35 mg/kg body weight, and GEG group (DNP+GEG at 0.75% in the diet for 8 weeks). Von Frey and open field tests were used to assess pain sensitivity and anxio-depressive behaviors, respectively. Colon and spinal cord were collected for gene expression analysis. 16S rRNA gene sequencing was done from cecal samples and microbiome data analysis was performed using QIIME 2. GEG supplementation mitigated mechanical hypersensitivity and anxio-depressive behavior in DNP animals. GEG supplementation suppressed the dynamin-related protein 1 protein expression (colon) and gene expression (spinal cord), astrocytic marker GFAP gene expression (colon and spinal cord), and tumor necrosis factor-α gene expression (colon, P < .05; spinal cord, P = .0974) in DNP rats. GEG supplementation increased microglia/macrophage marker CD11b gene expression in colon and spinal cord of DNP rats. GEG treatment increased abundance of Acinetobacter, Azospirillum, Colidextribacter, and Fournierella but decreased abundance of Muribaculum intestinale in cecal feces of rats. This study demonstrates that GEG supplementation decreased pain, anxio-depression, and neuroimmune cells, and improved the composition of gut microbiomes and mitochondrial function in rats with diabetic neuropathy.

4. Painful diabetic polyneuropathy

INTRODUCTION

Pain as a symptom of diabetic polyneuropathy (DPN) significantly lowers quality of life, increases mortality and is the main reason for patients with diabetes to seek medical attention. The number of people suffering from painful diabetic polyneuropathy (PDPN) has increased significantly over the past decades.

METHODS

The literature on the diagnosis and treatment of diabetic polyneuropathy was retrieved and summarized.

RESULTS

The etiology of PDPN is complex, with primary damage to peripheral nociceptors and altered spinal and supra-spinal modulation. To achieve better patient outcomes, the mode of diagnosis and treatment of PDPN evolves toward more precise pain-phenotyping and genotyping based on patient-specific characteristics, new diagnostic tools, and prior response to pharmacological treatments. According to the Toronto Diabetic Neuropathy Expert Group, a presumptive diagnosis of "probable PDPN" is sufficient to initiate treatment. Proper control of plasma glucose levels, and prevention of risk factors are essential in the treatment of PDPN. Mechanism-based pharmacological treatment should be initiated as early as possible. If symptomatic pharmacologic treatment fails, spinal cord stimulation (SCS) should be considered. In isolated cases, where symptomatic pharmacologic treatment and SCS are unsuccessful or cannot be used, sympathetic lumbar chain neurolysis and/or radiofrequency ablation (SLCN/SLCRF), dorsal root ganglion stimulation (DRGs) or posterior tibial nerve stimulation (PTNS) may be considered. However, it is recommended that these treatments be applied only in a study setting in a center of expertise.

CONCLUSIONS

The diagnosis of PDPN evolves toward pheno-and genotyping and treatment should be mechanism-based.

Mitochondria-derived peptide is an effective target for treating streptozotocin induced painful diabetic neuropathy through induction of activated protein kinase/peroxisome proliferator-activated receptor gamma coactivator 1alpha -mediated mitochondrial biogenesis

Painful Diabetic Neuropathy (PDN) is a common diabetes complication that frequently causes severe hyperalgesia and allodynia and presents treatment challenges. Mitochondrial-derived peptide (MOTS-c), a novel mitochondrial-derived peptide, has been shown to regulate glucose metabolism, insulin sensitivity, and inflammatory responses. This study aimed to evaluate the effects of MOTS-c in streptozocin (STZ)-induced PDN model and investigate the putative underlying mechanisms. We found that endogenous MOTS-c levels in plasma and spinal dorsal horn were significantly lower in STZ-treated mice than in control animals. Accordingly, MOTS-c treatment significantly improves STZ-induced weight loss, elevation of blood glucose, mechanical allodynia, and thermal hyperalgesia; however, these effects were blocked by dorsomorphin, an adenosine monophosphate-activated protein kinase (AMPK) inhibitor. In addition, MOTS-c treatment significantly enhanced AMPKα1/2 phosphorylation and PGC-1α expression in the lumbar spinal cord of PDN mice. Mechanistic studies indicated that MOTS-c significantly restored mitochondrial biogenesis, inhibited microglia activation, and decreased the production of pro-inflammatory factors, which contributed to the alleviation of pain. Moreover, MOTS-c decreased STZ-induced pain hypersensitivity in PDN mice by activating AMPK/PGC-1α signaling pathway. This provides the pharmacological and biological evidence for developing mitochondrial peptide-based therapeutic agents for PDN.

Natural compounds efficacy in complicated diabetes: A new twist impacting ferroptosis

Ferroptosis, as a way of cell death, participates in the body's normal physiological and pathological regulation. Recent studies have shown that ferroptosis may damage glucose-stimulated islets β Insulin secretion and programmed cell death of T2DM target organs are involved in the pathogenesis of T2DM and its complications. Targeting suppression of ferroptosis with specific inhibitors may provide new therapeutic opportunities for previously untreated T2DM and its target organs. Current studies suggest that natural bioactive compounds, which are abundantly available in drugs, foods, and medicinal plants for the treatment of T2DM and its target organs, have recently received significant attention for their various biological activities and minimal toxicity, and that many natural compounds appear to have a significant role in the regulation of ferroptosis in T2DM and its target organs. Therefore, this review summarized the potential treatment strategies of natural compounds as ferroptosis inhibitors to treat T2DM and its complications, providing potential lead compounds and natural phytochemical molecular nuclei for future drug research and development to intervene in ferroptosis in T2DM.

Acupuncture for painful diabetic peripheral neuropathy: a systematic review and meta-analysis

Background

Painful Diabetic Peripheral Neuropathy (PDPN) is a common complication of diabetes, it severely affects the quality of life of patients. Acupuncture has been shown to be effective in the treatment of PDPN. To evaluate the efficacy and safety of acupuncture for pain relief in patients diagnosed with diabetic peripheral neuropathy, we conducted a systematic review and meta-analysis.

Method

We thoroughly searched specific databases, which included PUBMED, EMBASE, Web of Science, the Cochrane Library, the Chinese Biomedical Literature Database, the Chinese National Knowledge Infrastructure, China Science and Technology Journal Database and the Wanfang Data. All randomized controlled trials of acupuncture therapy for PDPN with pain change scales were included. Included studies were assessed for methodological quality according to the risk of bias from the Cochrane handbook. Meta-analyses were carried out to analyze the outcomes, subgroup analyses, sensitivity analyses, and funnel plot analyses were undertaken.

Results

This systematic review evaluated a total of 25 trials of acupuncture therapy in combination with conventional treatment, involving a total of 1,561 patients with PDPN. According to the results, among 16 trials using VAS scores with a total of 1,552 patients, 2 acupoint injection trials (MD -2.38, 95% CI: -2.76 to -2.01, p < 0.00001), 12 acupuncture trials (MD -1. 31, 95% CI: -1.60 to -1.02, p < 0.00001) and 2 moxibustion trials showed that acupuncture therapy combined with conventional treatment improved pain better than conventional treatment (MD -2.50, 95% CI: -2.76 to -2.24, p < 0.00001). In the subgroup analysis of the acupuncture group, the results of the 5 trials in which the location of acupuncture was only in the limbs (MD -1.27, 95% CI: -1.54 to -1.01, p < 0.00001) and the 7 trials both in limbs and torso (MD -1.38, 95% CI: -1.81 to -0.95, p < 0.00001) also demonstrated that acupuncture was effective in pain improvement.

Conclusion

This meta-analysis analyzed the possible efficacy of acupuncture in combination with conventional treatment for pain in diabetic peripheral neuropathy, particularly when acupoints are located in the limbs. However, there are limitations to this meta-analysis and future clinical studies are needed to confirm these findings.

Systematic review registration

https://www.crd.york.ac.uk/prospero/display_record.php?ID=CRD42023449447, identifier (CRD42023449447).

BTD: A TRPC5 activator ameliorates mechanical allodynia in diabetic peripheral neuropathic rats by modulating TRPC5-CAMKII-ERK pathway

Mechanical allodynia is a serious complication of painful diabetic neuropathy (PDN) with limited treatment options. The transient receptor potential canonical 5 (TRPC5) channel is a promising target in pain; however, its role in painful diabetic neuropathy has not yet been elucidated. In this study, we have investigated the role of TRPC5 channels using BTD [N-{3-(adamantan-2-yloxy)-propyl}-3-(6-methyl-1,1-dioxo-2H-1λ6,2,4-benzothiadiazin-3-yl)-propanamide)],a potent TRPC5 activator and HC070, as TRPC5 channel inhibitor in rat model of PDN. In this study, streptozotocin was used to induce diabetes in male Sprague-Dawley rats. The alterations in mechanical and thermal pain thresholds, nerve functional deficits in diabetic animals were assessed by various behavioral and functional parameters.TRPC5 involvement was investigated by treating neuropathic rats with BTD, TRPC5 channel activator (1 and 3 mg/kg, i.p. for 14 days) and HC070, a TRPC5 channel inhibitor (1 and 3 mg/kg). BTD and HC070 effects in pain reduction were assessed by western blotting, estimating oxidative stress and inflammatory markers in the lumbar spinal cord. BTD treatment (3 mg/kg, i.p.) once daily for 14 days ameliorated mechanical allodynia but not thermal hyposensation or nerve functional deficit in diabetic neuropathic rats. BTD treatment down-regulated TRPC5 expression by increasing the activity of protein kinase C. It also subsequently down-regulated the downstream pain markers (CAMKII, ERK) in the spinal cord. Additionally, a decrease in inflammatory cytokines (TNF-α, IL-6) also demonstrated BTD's potent anti-inflammatory properties in reducing mechanical allodynia. On the other hand, HC070 did not exert any beneficial effects on behavioural and nerve functional parameters. The study concludes that BTD ameliorated mechanical allodynia in a rat model of painful diabetic neuropathy not only through modulation of the TRPC5-CAMKII-ERK pathway but also through its anti-inflammatory and anti-apoptotic properties. Overall, BTD is a promising therapeutic molecule in the treatment of mechanical allodynia in painful diabetic neuropathy.

The mediating role of HbA1c in the association between elevated low-density lipoprotein cholesterol levels and diabetic peripheral neuropathy in patients with type 2 diabetes mellitus

BACKGROUND

Increased levels of low-density lipoprotein cholesterol (LDL-C) have been identified as one potential risk factor for diabetic peripheral neuropathy (DPN) in patients. The current study seeks to clarify the link between LDL-C, hyperglycemia, and DPN in patients with type 2 diabetes mellitus (T2DM).

METHODS

Here, a total of 120 T2DM individuals were recruited. These volunteers with T2DM were divided into 2 groups, based on the presence or absence of peripheral neuropathy. Additionally, their baseline characteristics were compared. Association among LDL-C and glycosylated hemoglobin (HbA1c) levels and DPN, particularly with respect to specific nerve conduction velocity were analyzed. To identify factors influencing DPN, regression was performed. Furthermore, mediation analysis was employed to evaluate the indirect, direct and total effects of LDL-C on specific nerve conduction velocity, with HbA1c serving as a mediator.

RESULTS

Compared to 55 patients without DPN, 65 patients with DPN demonstrated elevated levels of LDL-C and HbA1c. Both LDL-C and HbA1c have been found to be associated with reduced the motor fiber conduction velocities of Ulnar (or the Common peroneal) nerve in diabetic patients. HbA1c is one of the known risk factors for DPN in individuals with T2DM. Further mediation analysis revealed that the effect of LDL-C on the Ulnar (or the Common peroneal) nerve motor fiber conduction velocities are fully mediated by HbA1c in patients with T2DM.

CONCLUSIONS

The impact of elevated LDL-C levels upon the Ulnar (or the Common peroneal) nerve motor fiber conduction velocities in patients with T2DM was found to be entirely mediated by increased HbA1c levels.

Long-Term Evaluation of Spinal Cord Stimulation in Patients With Painful Diabetic Polyneuropathy: An Eight-to-Ten-Year Prospective Cohort Study

OBJECTIVE

This study aimed to evaluate the long-term effects of spinal cord stimulation (SCS) in patients with painful diabetic polyneuropathy (PDPN).

MATERIALS AND METHODS

This prospective cohort study was the eight-to-ten-year follow-up of a previously performed pilot and randomized controlled trial on the effects of SCS in PDPN, initiated by the multidisciplinary pain center of Maastricht University Medical Center+. The study population consisted of a subgroup of patients who still used SCS treatment ≥ eight years after implantation (n = 19). Pain intensity scores (numeric rating scale [NRS]) during the day and night and data on secondary outcomes (ie, quality of life, depression, sleep quality) were reported during yearly follow-up consultations. Long-term efficacy of SCS was analyzed by comparing the most recently obtained data eight to ten years after implantation with those obtained at baseline.

RESULTS

Pain intensity, day and night, was significantly (p < 0.01) reduced by 2.3 (NRS 6.6-4.3) and 2.2 (NRS 6.8-4.6) points, respectively, when comparing the long-term data with baseline. Moreover, for > 50% of patients, the pain reduction was > 30%, which is considered clinically meaningful. No differences were found regarding the secondary outcomes.

CONCLUSION

This eight-to-ten-year follow-up study indicates that SCS can remain an effective treatment in the long term to reduce pain intensity in a subcohort of patients with PDPN who still had an SCS device implanted after eight years.

Serum Uric Acid Levels Are Related to Diabetic Peripheral Neuropathy, Especially for Motor Conduction Velocity of Tibial Nerve in Type 2 Diabetes Mellitus Patients

Background

Oxidative stress is one of the most critical factors that contribute to the pathogenesis of neuronal damage, including diabetic peripheral neuropathy (DPN). Uric acid is a kind of natural antioxidant that plays a major role in the antioxidant capacity against oxidative stress. Here, we aim to determine the role of serum uric acid (SUA) in the DPN of patients with type 2 diabetes mellitus (T2DM). Patients and Methods. 106 patients with T2DM were recruited and divided into the DPN group and the control group. Clinical parameters, especially for motor nerve fiber conduction velocity and sensory nerve fiber conduction velocity, were collected. Differences between T2DM patients with and without DPN were compared. Correlation and regression analyses were performed to explore the association between SUA and DPN.

Results

Compare with 57 patients with DPN, 49 patients without DPN showed lower HbA1c and elevated SUA levels. Additionally, SUA levels are negatively associated with the motor conduction velocity of tibial nerve with or without adjusting for HbA1c. Besides, it is suggested that decreased SUA levels may influence the motor conduction speed of the tibial nerve by multiple linear regression analysis. Moreover, we demonstrated that decreased SUA level is a risk factor for DPN in patients with T2DM by binary logistic regression analysis.

Conclusion

Lower SUA is a risk factor for DPN in patients with T2DM. Additionally, decreased SUA may influence the damage of peripheral neuropathy, especially for motor conduction velocity of the tibial nerve.

PGC1α: an emerging therapeutic target for chemotherapy-induced peripheral neuropathy

Chemotherapy-induced peripheral neuropathy (CIPN)-mediated paresthesias are a common complication in cancer patients undergoing chemotherapy. There are currently no treatments available to prevent or reverse CIPN. Therefore, new therapeutic targets are urgently needed to develop more effective analgesics. However, the pathogenesis of CIPN remains unclear, and the prevention and treatment strategies of CIPN are still unresolved issues in medicine. More and more studies have demonstrated that mitochondrial dysfunction has become a major factor in promoting the development and maintenance of CIPN, and peroxisome proliferator-activated receptor gamma (PPARγ) coactivator 1α (PGC1α) plays a significant role in maintaining the mitochondrial function, protecting peripheral nerves, and alleviating CIPN. In this review, we highlight the core role of PGC1α in regulating oxidative stress and maintaining normal mitochondrial function and summarize recent advances in its therapeutic effects and mechanisms in CIPN and other forms of peripheral neuropathy. Emerging studies suggest that PGC1α activation may positively impact CIPN mitigation by modulating oxidative stress, mitochondrial dysfunction, and inflammation. Therefore, novel therapeutic strategies targeting PGC1α could be a potential therapeutic target in CIPN.

Diabetes mellitus differently affects electrical membrane properties of vagal afferent neurons of rats

To study whether diabetes mellitus (DM) would cause electrophysiological alterations in nodose ganglion (NG) neurons, we used patch clamp and intracellular recording for voltage and current clamp configuration, respectively, on cell bodies of NG from rats with DM. Intracellular microelectrodes recording, according to the waveform of the first derivative of the action potential, revealed three neuronal groups (A0 , Ainf , and Cinf ), which were differently affected. Diabetes only depolarized the resting potential of A0 (from -55 to -44 mV) and Cinf (from -49 to -45 mV) somas. In Ainf neurons, diabetes increased action potential and the after-hyperpolarization durations (from 1.9 and 18 to 2.3 and 32 ms, respectively) and reduced dV/dtdesc (from -63 to -52 V s-1 ). Diabetes reduced the action potential amplitude while increasing the after-hyperpolarization amplitude of Cinf neurons (from 83 and -14 mV to 75 and -16 mV, respectively). Using whole cell patch clamp recording, we observed that diabetes produced an increase in peak amplitude of sodium current density (from -68 to -176 pA pF-1 ) and displacement of steady-state inactivation to more negative values of transmembrane potential only in a group of neurons from diabetic animals (DB2). In the other group (DB1), diabetes did not change this parameter (-58 pA pF-1 ). This change in sodium current did not cause an increase in membrane excitability, probably explainable by the alterations in sodium current kinetics, which are also induced by diabetes. Our data demonstrate that diabetes differently affects membrane properties of different nodose neuron subpopulations, which likely have pathophysiological implications for diabetes mellitus.

Association between short-term exposure to extreme humidity and painful diabetic neuropathy: a case-crossover analysis

Painful diabetic neuropathy (PDN) is a common complication of diabetes mellitus, which reduces the quality of life. However, the association between PDN and environmental factors, especially ambient humidity, remains unclear. Therefore, this study investigated the impact of extreme humidity events on PDN. Data on PDN-related hospital admissions to two tertiary hospitals in Hefei, China (2014-2019) were obtained. A distributed lag non-linear model with a case-crossover design was used to quantitatively estimate the effects of ambient humidity on PDN, and the results were stratified by sex and age. The 1st, 10th, 90th, and 99th percentiles of relative humidity (RHU) were defined as extreme humidity, and the average relative humidity (74.94%) was set as the reference value. Non-linear exposure-response curves between the RHU and PDN cases were obtained. Extreme humidity (92%) had a significant effect on PDN with a relative risk (RR) of 1.13 (95% confidence interval (CI): 1.01-1.26) on a particular day, which increased with the RHU (RR: 1.21, 95% CI: 1.02-1.45 at 98% extreme humidity). Stratification analysis showed that women (RR: 1.38, 95% CI: 1.07-1.77) and patients aged < 65 years (RR: 1.26, 95% CI: 1.01-1.57) were highly susceptible to this effect on the same day. The results suggest that extreme humidity is a crucial trigger for PDN onset in diabetes patients. Furthermore, the effects vary with sex and age. This study provides detailed evidence of the adverse effects of extreme weather on diabetes patients.

High Blood Glucose and Excess Body fat Enhance Pain Sensitivity and Weaken Pain Inhibition in Healthy Adults: A Single-blind Cross-over Randomized Controlled Trial

To investigate links between blood glucose, body fat mass and pain, the effects of acute hyperglycaemia on pain sensitivity and pain inhibition were examined in healthy adults with normal (n = 24) or excess body fat (n = 20) determined by dual-energy X-ray absorptiometry. Effects of hyperglycaemia on heart rate variability and reactive hyperaemia were also explored. For the overall sample, ingesting 75-g glucose enhanced pain sensitivity during 1-minute cold-water immersion of both feet (conditioning stimulus) and weakened the pain inhibitory effect of cold water on pressure pain thresholds (test stimulus). Exploratory subgroup analyses not adjusted for multiple comparisons suggested that this effect was limited to people with excess fat mass. In addition, acute hyperglycaemia suppressed resting heart rate variability only in people with excess fat mass. Furthermore, regardless of blood glucose levels, people with excess fat mass had weaker pain inhibition for pinprick after cold water and reported more pain during 5-minutes of static blood flow occlusion. Neither high blood glucose nor excess body fat affected pinprick-temporal summation of pain or reactive hyperaemia. Together, these findings suggest that hyperglycaemia and excess fat mass interfere with pain processing and autonomic function. PERSPECTIVE: Ingesting 75-g glucose (equivalent to approximately 2 standard cans of soft drink) interfered with pain-processing and autonomic function, particularly in people with excess body fat mass. As both hyperglycaemia and overweight are risk factors for diabetes, whether these are sources of pain in people with diabetes should be further explored.

Identification of Immune Infiltration and the Potential Biomarkers in Diabetic Peripheral Neuropathy through Bioinformatics and Machine Learning Methods

Diabetic peripheral neuropathy (DPN) is one of the most common chronic complications in diabetes. Previous studies have shown that chronic neuroinflammation was associated with DPN. However, further research is needed to investigate the exact immune molecular mechanism underlying the pathogenesis of DPN. Expression profiles were downloaded from the Gene Expression Omnibus (GEO) database. Differentially expressed genes (DEGs) were screened by R software. After functional enrichment analysis of DEGs, a protein-protein interaction (PPI) network analysis was performed. The CIBERSORT algorithm was used to evaluate the infiltration of immune cells in DPN. Next, the least absolute shrinkage and selection operator (LASSO) logistic regression and support vector machine-recursive feature elimination (SVM-RFE) algorithms were applied to identify potential DPN diagnostic markers. Finally, the results were further validated by qRT-PCR. A total of 1308 DEGs were screened in this study. Enrichment analysis identified that DEGs were significantly enriched in immune-related biological functions and pathways. Immune cell infiltration analysis found that M1 and M2 macrophages, monocytes, resting mast cells, resting CD4 memory T cells and follicular helper T cells were involved in the development of DPN. LTBP2 and GPNMB were identified as diagnostic markers of DPN. qRT-PCR results showed that 15 mRNAs, including LTBP2 and GPNMB, were differentially expressed, consistent with the microarray results. In conclusion, LTBP2 and GPNMB can be used as novel candidate molecular diagnostic markers for DPN. Furthermore, the infiltration of immune cells plays an important role in the progression of DPN.

Diyabetik Periferik Polinöropatili Hastalarda İnterlökin-23R Gen Polimofizmleri

Amaç: Diyabetik nöropatinin patogenezinde proinflamatuar ve nörovasküler değişiklikler suçlanmaktadır. Diyabetin vasküler inflamasyonu tetiklediği kabul edilse de inflamasyonun da diyabeti tetikleyebileceği öne sürülmüştür. İnterlökin-23 (IL-23) aktive makrofajlar ve dendritik hücreler tarafından salgılanan proinflamatuar bir sitokindir. Interleukin-23R'nin kronik inflamatuar hastalıklarda kritik bir rolü olduğu bilinmektedir. Bu çalışmanın amacı, IL-23R polimorfizmi ile diyabetik periferik nöropati arasındaki ilişkiyi incelemektir. Yöntem: Nöroloji polikliniğine başvuran 50 diyabetik periferik nöropati hastası ve hasta grubuna yaş ve cinsiyet açısından uyumlu 52 sağlıklı kontrol çalışmaya dahil edildi. Çalışmaya katılmayı kabul eden gönüllülerin tamamına elektromiyografi uygulandı ve EDTA'lı tüplere 2 ml kan örneği alındı. Pyrosequencing yöntemi ile IL-23R gen polimorfizmi analiz edildi. Bulgular: IL-23R gen varyantları rs2201841, rs199542433, rs201052419, rs11209026 diyabetik periferik nöropati (DPN) hastalarında ve kontrol grubunda analiz edildi. IL23R polimorfizmleri sıklıkları açısından hasta ve kontrol grupları arasında anlamlı bir fark saptanmadı. Ancak, odd’s oranlarına bakıldığında, rs2201841'in koruyucu rolü var gibi görünmekte, rs199542433 hem baskın hem de çekinik modellerde ve rs11209026 sadece çekinik modelde, DPN için 10 kata kadar daha yüksek risklerle ilişkili olabileceği görünmektedir. Sonuç: IL-23R gen polimorfizminin birçok otoimmün ve inflamatuar hastalık ile ilişkili olduğu gösterilmiştir. İnflamasyonun diyabet üzerinde önemli bir etkisi olduğu bilinmektedir. Diyabetik periferik nöropatide IL-23R gen polimorfizminin sıklığı anlamlı değildi. Çalışmamız diyabetik periferik nöropatide IL-23R gen polimorfizminin rolünü araştıran tek ve ilk çalışmadır. Etnik köken, genetik çalışmalarda çok önemlidir ve bu çalışmanın başka etnik kökene sahip hastalarda yapılması ve daha geniş çalışma gruplarının alınması, bize ilerisi için daha net bilgiler verecektir.

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.