New perspectives in diabetic neuropathy

Diabetic peripheral neuropathy and neuromodulation techniques: a systematic review of progress and prospects

Neuromodulation for diabetic peripheral neuropathy represents a significant area of interest in the management of chronic pain associated with this condition. Diabetic peripheral neuropathy, a common complication of diabetes, is characterized by nerve damage due to high blood sugar levels that lead to symptoms, such as pain, tingling, and numbness, primarily in the hands and feet. The aim of this systematic review was to evaluate the efficacy of neuromodulatory techniques as potential therapeutic interventions for patients with diabetic peripheral neuropathy, while also examining recent developments in this domain. The investigation encompassed an array of neuromodulation methods, including frequency rhythmic electrical modulated systems, dorsal root ganglion stimulation, and spinal cord stimulation. This systematic review suggests that neuromodulatory techniques may be useful in the treatment of diabetic peripheral neuropathy. Understanding the advantages of these treatments will enable physicians and other healthcare providers to offer additional options for patients with symptoms refractory to standard pharmacologic treatments. Through these efforts, we may improve quality of life and increase functional capacity in patients suffering from complications related to diabetic neuropathy.

Retroauricular subperiosteal vs systemic intravenous glucocorticoid administration on efficacy and blood glucose in diabetic patients with sudden deafness

BACKGROUND

Managing sudden deafness (SD) in patients with diabetes mellitus (DM) is particularly challenging due to the heightened risk of adverse effects associated with systemic drug administration. This study explores the potential of retroauricular subperiosteal injection as a localized drug delivery method for a more effective and safe treatment.

AIM

To compare the efficacy of retroauricular subperiosteal injection vs systemic intravenous glucocorticoid (GC) administration for SD in patients with DM and assess the effects on blood glucose levels.

METHODS

A total of 128 cases of type 2 DM (T2DM) with SD diagnosed and treated in Zibo Central Hospital from February 2021 to July 2023 were divided into two groups: An observation group (66 cases receiving retroauricular subperiosteal injection of methylprednisolone) and a control group (62 cases receiving systemic intravenous administration of methylprednisolone). The two groups were compared in terms of therapeutic efficacy, hearing recovery, blood glucose level changes, and incidence of adverse reactions. Binary logistic regression was used to analyze the factors affecting therapeutic efficacy.

RESULTS

The observation group showed a significantly higher total effective rate (90.91%) compared with the control group (75.81%, P < 0.05). Additionally, pure-tone hearing threshold, fasting plasma glucose, and 2-hour postprandial blood glucose were significantly lower in the observation group compared with the control group (P < 0.05). The incidence of adverse reactions was also lower in the observation group than in the control group (7.58% vs 22.58%, P < 0.05). A T2DM course longer than 5 years and systemic intravenous GC administration were identified as independent risk factors for treatment inefficacy (P < 0.05).

CONCLUSION

In treating patients with diabetes and SD, retroauricular subperiosteal injection of methylprednisolone offers superior therapeutic efficacy and lower incidence of adverse reactions compared with systemic intravenous GC administration, with minimal impact on blood glucose.

Identification and validation of serum amino acids as diagnostic biomarkers for diabetic peripheral neuropathy

BACKGROUND

Diabetic peripheral neuropathy (DPN) is the most prevalent complication of type 2 diabetes mellitus (T2DM). Due to a lack of specific biomarkers, the early diagnosis of this disorder is limited.

AIM

To identify and validate serum amino acids that could discriminate T2DM patients with DPN from those without DPN.

METHODS

T2DM patients with DPN, T2DM patients without DPN, and healthy controls were recruited for this study. The participants comprised two nonoverlapping cohorts: A training cohort (DPN = 84 participants, T2DM = 82 participants, normal = 50 participants) and a validation cohort (DPN = 112 participants, T2DM = 93 participants, normal = 58 participants). A prediction model of the ability of serum amino acids to distinguish DPN from T2DM was established using a logistic regression model, and area under the curve (AUC) analysis was used to evaluate the diagnostic ability of the model. In addition, the serum amino acid levels of 13 DPN patients were also detected before treatment and after 3 months of treatment.

RESULTS

A clinical detection method for the diagnosis of DPN based on a biomarker panel of three serum amino acids and diabetes duration was developed. The diagnostic model demonstrated AUC values of 0.805 (95%CI: 0.739-0.871) and 0.810 (95%CI: 0.750-0.870) in the training and verification cohorts, respectively. In the identification of T2DM patients and normal controls, the AUC values were 0.891 (95%CI: 0.836-0.945) and 0.883 (95%CI: 0.832-0.934) in the training and validation cohorts, respectively. Arginine and tyrosine levels were increased after treatment, whereas aspartic acid levels were decreased after treatment.

CONCLUSION

This study successfully identified and validated the metabolomic significance of arginine, tyrosine, and glutamic acid as potential biomarkers for diagnosing DPN. These findings are particularly valuable, as they establish a foundational step toward developing the first routine laboratory test for DPN. Moreover, the diagnostic model that was constructed in this study effectively distinguishes DPN patients from those with T2DM without neuropathy, thereby potentially facilitating early diagnosis and intervention.

Upregulation of Acid-Sensing Ion Channel 1a in the Anterior Cingulate Cortex by TNF-α/NF-κB Pathway Contributes to Diabetes-Related Pain

Effective treatment strategies for diabetes-related pain are limited because of its complex pathogenesis, particularly brain mechanisms underlying this disease. The acid-sensing ion channel 1a (ASIC1a) has emerged as a key player in the development and treatment of various types of pain. We investigated the role of ASIC1a in diabetes-related pain and its molecular mechanisms in the anterior cingulate cortex (ACC). Our findings demonstrate that the upregulation of ASIC1a expression drives enhanced activity of excitatory glutamatergic neurons in the ACC (ACCGlu), promoting the development of pain hypersensitivity in streptozotocin (STZ)-induced diabetic male mice. Pharmacologic inhibition and genetic knockout of ASIC1a in ACCGlu neurons significantly reduced neuronal activity and alleviated mechanical and thermal pain sensitizations in STZ-induced diabetes. Furthermore, increased levels of tumor necrosis factor-α (TNF-α) in the ACC upregulated ASIC1a by triggering nuclear factor-κB (NF-κB) pathways, which led to the development of diabetes-related pain. Notably, the clinically used medication, infliximab, exhibited therapeutic effects on diabetes-related pain via its influence on TNF-α/NF-κB/ASIC1a pathway in STZ-treated mice. Collectively, this study identifies ASIC1a as a potential therapeutic target for diabetes-related pain and shows the neutralization of TNF-α leads to pain relief through the TNF-α/NF-κB/ASIC1a pathway in the ACC. These findings hold promise for the development of new clinical therapeutic strategies for diabetes-related pain.

ARTICLE HIGHLIGHTS

Upregulation of acid-sensing ion channel 1a (ASIC1a) expression in anterior cingulate cortex (ACC) glutamatergic (ACCGlu) neurons drives diabetes-related pain hypersensitivity in mice, and pharmacologic inhibition and genetic knockout of ASIC1a in ACCGlu neurons significantly reduce neuronal hyperactivity and alleviate pain. Tumor necrosis factor-α/nuclear factor-κB signaling in the ACC elevates ASIC1a expression, mechanistically linking neuroinflammation to pain development in diabetic mice. ASIC1a is a potential therapeutic target for diabetes-related pain, offering a pathway-specific strategy for treatment development.

Multi-omic integration with human dorsal root ganglia proteomics highlights TNFα signalling as a relevant sexually dimorphic pathway

ABSTRACT

The peripheral nervous system (PNS) plays a critical role in pathological conditions, including chronic pain disorders, that manifest differently in men and women. To investigate this sexual dimorphism at the molecular level, we integrated quantitative proteomic profiling of human dorsal root ganglia (hDRG) and peripheral nerve tissue into the expanding omics framework of the PNS. Using data-independent acquisition (DIA) mass spectrometry, we characterized a comprehensive proteomic profile, validating tissue-specific differences between the hDRG and peripheral nerve. Through multi-omic analyses and in vitro functional assays, we identified sex-specific molecular differences, with TNFα signalling emerging as a key sexually dimorphic pathway with higher prominence in men. Genetic evidence from genome-wide association studies further supports the functional relevance of TNFα signalling in the periphery, while clinical trial data and meta-analyses indicate a sex-dependent response to TNFα inhibitors. Collectively, these findings underscore a functionally sexual dimorphism in the PNS, with direct implications for sensory and pain-related clinical translation.

Macrovascular and microvascular complications in US Medicare enrollees with type 2 diabetes with and without atherosclerotic cardiovascular disease

AIMS

To assess the incidence of macrovascular and microvascular complications in US Medicare enrollees diagnosed with T2D with and without established ASCVD.

MATERIALS AND METHODS

We conducted a retrospective cohort study using Medicare fee-for-service claims data from 1 January 2006, through 31 December 2021. Baseline demographic and clinical characteristics were assessed in the 1-year prior to indexing. Cumulative incidences of various diabetes complications were assessed until the first microvascular or macrovascular complication of interest, the end of the study period or death.

RESULTS

A total of 2 326 726 patients and 640 666 patients met study inclusion/exclusion criteria for the T2D cohort and T2D + ASCVD sub-cohort, respectively. The incidence rate of any macrovascular event was 483.34 per 10 000 person-years in the T2D cohort. Overall, the 1-year cumulative incidence rate of any macrovascular event was 3.90%. Coronary heart disease (T2D, 3.24%; T2D + ASCVD, 8.10%) and peripheral artery disease (T2D, 1.97%; T2D + ASCVD, 7.33%) were the macrovascular events with the greatest 1-year cumulative incidence. Patients developed microvascular complications at a rate of 1569.28 per 10 000 person-years in the T2D cohort and 1859.80 per 10 000 person-years in the T2D + ASCVD sub-cohort. The 1-year cumulative incidence of any microvascular event was 16.88% in the T2D cohort and 21.16% in the T2D + ASCVD sub-cohort. Neuropathy and nephropathy were the microvascular events with the greatest 1-year cumulative incidence in both cohorts: T2D, 8.34% and 7.02%; T2D + ASCVD, 10.65% and 9.12%, respectively.

CONCLUSIONS

The frequencies of macrovascular and microvascular complications highlight the importance of annual cardiovascular risk assessment in patients with T2D, especially those with established ASCVD.

Nageotte nodules in human dorsal root ganglia reveal neurodegeneration in diabetic peripheral neuropathy

Nageotte nodules, first described in 1922 by Jean Nageotte, are clusters of non-neuronal cells that form after sensory neuron death. Despite their historical recognition, little is known about their molecular identity nor their involvement in neuropathies that involve neuronal loss like diabetic peripheral neuropathy (DPN). In this study, we molecularly characterize Nageotte nodules in dorsal root ganglia recovered from organ donors with DPN. Here we show that Nageotte nodules are abundant in DPN sensory ganglia and account for 25% of all neurons. Peripherin-and Nav1.7-positive dystrophic axons invade Nageotte nodules, forming small neuroma-like structures. Using histology and spatial sequencing, we demonstrate that Nageotte nodules are mainly composed of satellite glia and non-myelinating Schwann cells that express SPP1 and are intertwined with sprouting sensory axons originating from neighboring neurons. Our findings suggest that Nageotte nodules are an integral feature of dorsal root ganglion neurodegeneration, providing potential therapeutic targets for sensory neuron protection and pain management in DPN.

Association between different triglyceride glucose index-related indicators and overactive bladder

BACKGROUND

Overactive bladder (OAB) is a syndrome marked by urinary urgency. Given the crucial role of metabolic anomalies in the pathogenesis of OAB, the aim of this study was to investigate the associations between different triglyceride glucose index (TyG)-related indicators and OAB.

METHODS

9024 participants aged ≥ 20 years from NHANES 2005-2018 were involved. Weighted multivariate logistic regression was employed to assess the relationship between three TyG-related indicators and OAB with subgroup and interaction analyses. In addition, ROC, DeLong's test and confusion matrix were further utilized to assess the predictive power of different indicators for OAB in the total population versus different subgroups of the population.

RESULTS

TyG-related indicators were positively associated with OAB. The associations were statistically different in age and physical activity subgroups (all p for interaction < 0.1). In the whole population, TyG-WHtR demonstrated the highest predictive ability, with the largest AUC of 0.625 (95 %CI: 0.609, 0.641), and was relatively more predictive in the < 60 years and moderate-to-vigorous physical activity subgroups.

CONCLUSIONS

Positive associations of TyG-related indicators with OAB were observed. TyG-WHtR has the strongest predictive performance for OAB in the total population.

Serum Neurofilament Light Chain and Structural and Functional Nerve Fiber Loss in Painful and Painless Diabetic Polyneuropathy

AIMS

To explore associations between the axonal protein neurofilament light chain (NfL) and severity of diabetic polyneuropathy (DPN) and pain.

METHODS

We performed cross-sectional analysis of a subset of the PiNS/DOLORisk cohort of people with DPN with and without neuropathic pain. Biobank samples were analyzed for serum NfL (s-NfL) using single molecule array. DPN was defined by Toronto criteria for probable or confirmed DPN. Painful DPN (PDPN) was evaluated according to IASP criteria. Measures of DPN severity included clinical DPN scales, quantitative sensory testing (QST) and intraepidermal nerve fiber density (IENFD).

RESULTS

Participants with confirmed (N = 172) or probable DPN (N = 29) were included. There was no s-NfL difference between participants with DPN (N = 79, 22.8 ng/L [IQR 17.4; 31.3]) and PDPN (N = 122, 22.2 ng/L [16.0; 34.4]). S-NfL was not associated with pain severity or DPN severity evaluated by clinical DPN scales. Higher s-NfL was associated with lower IENFD (13.6 % [95 % CI 3.1; 22.9], unit = 1 fiber/mm, N = 24) and more pronounced loss of nerve fiber function measured by QST (p-trend = 0.02).

CONCLUSIONS

Higher s-NfL was associated with nerve fiber dysfunction and loss quantified by QST and IENFD, but not with pain or clinical DPN scales. S-NfL may reflect the severity of nerve fiber damage underlying DPN.

Hypoxia-Driven Neurovascular Impairment Underlies Structural-Functional Dissociation in Diabetic Sudomotor Dysfunction

Sudomotor dysfunction in diabetic patients increases the risk of fissures, infections, and diabetic foot ulcers (DFUs), thereby reducing the quality of life. Despite its clinical importance, the mechanisms underlying this dysfunction remain inadequately elucidated. This study addresses this gap by demonstrating that despite structural integrity, sweat glands (SGs) in diabetic individuals with DFUs, and a murine model of diabetic neuropathy (DN), exhibit functional impairments, as confirmed by histological and functional assays. Integrated transcriptome and proteome analysis revealed significant upregulation of the SG microenvironment in response to hypoxia, highlighting potential underlying pathways involved. In addition, histological staining and tissue clearing techniques provided evidence of impaired neurovascular networks adjacent to SGs. Single-cell RNA sequencing unveiled intricate intercellular communication networks among endothelial cells (ECs), neural cells (NCs), and sweat gland cells (SGCs), emphasizing intricate cellular interactions within the SG microenvironment. Furthermore, an in vitro SGC-NC interaction model (SNIM) was employed to validate the supportive role of NCs in regulating SGC functions, highlighting the neurovascular-SG axis in diabetic pathophysiology. These findings confirm the hypoxia-driven upregulation of the SG microenvironment and underscore the critical role of the neurovascular-SG axis in diabetic pathophysiology, providing insights into potential therapeutic targets for managing diabetic complications and improving patient outcomes.

Low-intensity Pulsed Ultrasound Stimulation of the Intestine Improves Insulin Resistance in Type 2 Diabetes

OBJECTIVE

Ultrasound stimulation of internal organs and peripheral nerves has demonstrated promising potential in regulating blood glucose metabolism. This study aims to assess the effectiveness of low-intensity pulsed ultrasound stimulation (LIPUS) on intestine in improving insulin resistance with type 2 diabetes mellitus (T2DM).

METHODS

C57BL/6J mice, both normal and T2DM, were randomly divided into three groups: Control, T2D-sham, and T2D-LIPUS. The T2D-LIPUS group received LIPUS stimulation in the intestine. The parameters were as follows: 1 MHz frequency, 1.0 kHz pulse repetition frequency (PRF), 20% duty cycle, 100 mW/cm² intensity spatial average temporal average (ISATA), for 20 minutes per session, five days per week, over four weeks.

RESULTS

Blood glucose analysis indicated that mice in the T2D-LIPUS group displayed significantly lower area under the curve (AUC) of glucose tolerance tests (GTT) and insulin tolerance tests (ITT) (p < 0.001), HOMA-IR (p < 0.001), and fasting serum insulin levels (p < 0.01) compared to the T2D-sham group. LIPUS treatment effectively lowered serum levels of IL-1β (p < 0.001) and TNF-α (p < 0.01) along with mRNA expression levels of IL-1β (p < 0.01) and IL-18 (p < 0.001) in the intestines of T2DM mice. Additionally, Western blot analysis revealed a reduction in the protein levels of NLRP3, caspase-1, and GSDMD-N in the intestinal tissues of mice treated with LIPUS.

CONCLUSION

These findings suggest that LIPUS can reduce inflammation and cellular apoptosis, while improving insulin resistance by inhibiting the NLRP3/Caspase-1/GSDMD signaling pathway. This research introduces a novel, non-pharmacological approach for managing T2DM.

Proteomic and Metabolomic Analysis of the Neuroprotective Effects of Lycium Ruthenicum Polyphenols in Diabetic Peripheral Neuropathy Mice

Lycium ruthenicum polyphenols (LRP) have been proven to be anti-inflammatory, antioxidant, and neuroprotective phytochemicals. This study applies proteomics and metabolomics to LRP-treated db/db mice to explore its potential effects mechanism. The experiments were divided into three groups: normal control db/m group, diabetic peripheral neuropathy (DPN) db/db group, and LRP-treated db/db group. We examined physiological and biochemical indicators, behavioral indicators, and histopathology. As for the mechanism, we used TMT-based quantification proteomics and LC-MS/MS-based metabolomics for sciatic nerve and serum. After 8 weeks of treatment, the fasting blood glucose level, mechanical withdrawal threshold, and thermal hyperalgesia were significantly improved. Pathological examination showed a significant alleviation in sciatic nerve histomorphology in the LRP group. Proteomics and metabolomics showed that the interventional effects of LRP were enriched mainly in oxidative phosphorylation, cardiac muscle contraction, and serum metabolites were enriched mainly in amino acid metabolism. LRP improves neurological function by improving mitochondrial functions, promoting neuronal development, and ameliorating dysregulation of amino acid metabolism. These results provide theoretical evidence for LRP as a potential functional food ingredient for the prevention and treatment of DPN.

Lipid metabolism alterations in peripheral neuropathies

Alterations in lipid metabolism are increasingly recognized as central pathological hallmarks of inherited and acquired peripheral neuropathies. Correct lipid balance is critical for cellular homeostasis. However, the mechanisms linking lipid disturbances to cellular dysfunction and whether these changes are primary drivers or secondary effects of disease remain unresolved. This is particularly relevant in the peripheral nervous system, where the lipid-rich myelin integrity is critical for axonal function, and even subtle perturbations can cause widespread effects. This review explores the role of lipids as structural components as well as signaling molecules, emphasizing their metabolic role in peripheral neurons and Schwann cells. Additionally, we explore the genetic and environmental connections in both inherited and acquired peripheral neuropathies, respectively, which are known to affect lipid metabolism in peripheral neurons or Schwann cells. Overall, we highlight how understanding lipid-centric mechanisms could advance biomarker discovery and therapeutic interventions for peripheral nerve disorders.

Diabetic neuropathy: cutting-edge research and future directions

Diabetic neuropathy (DN) is a prevalent and debilitating complication of diabetes mellitus, significantly impacting patient quality of life and contributing to morbidity and mortality. Affecting approximately 50% of patients with diabetes, DN is predominantly characterized by distal symmetric polyneuropathy, leading to sensory loss, pain, and motor dysfunction, often resulting in diabetic foot ulcers and lower-limb amputations. The pathogenesis of DN is multifaceted, involving hyperglycemia, dyslipidemia, oxidative stress, mitochondrial dysfunction, and inflammation, which collectively damage peripheral nerves. Despite extensive research, disease-modifying treatments remain elusive, with current management primarily focusing on symptom control. This review explores the complex mechanisms underlying DN and highlights recent advances in diagnostic and therapeutic strategies. Emerging insights into the molecular and cellular pathways have unveiled potential targets for intervention, including neuroprotective agents, gene and stem cell therapies, and innovative pharmacological approaches. Additionally, novel diagnostic tools, such as corneal confocal microscopy and biomarker-based tests, have improved early detection and intervention. Lifestyle modifications and multidisciplinary care strategies can enhance patient outcomes. While significant progress has been made, further research is required to develop therapies that can effectively halt or reverse disease progression, ultimately improving the lives of individuals with DN. This review provides a comprehensive overview of current understanding and future directions in DN research and management.

Investigating the Effect and Mechanism of 3-Methyladenine Against Diabetic Encephalopathy by Network Pharmacology, Molecular Docking, and Experimental Validation

Background/Objectives: Diabetic encephalopathy (DE), a severe neurological complication of diabetes mellitus (DM), is characterized by cognitive dysfunction. 3-Methyladenine (3-MA), a methylated adenine derivative, acts as a biomarker for DNA methylation and exhibits hypoglycemic and neuroprotective properties. However, the pharmacological mechanisms underlying 3-MA's therapeutic effects on diabetic microvascular complications remain incompletely understood, owing to the intricate and multifactorial pathogenesis of DE. Methods: This study employed network pharmacology and molecular docking techniques to predict potential targets and signaling pathways of 3-MA against DE, with subsequent validation through animal experiments to elucidate the molecular mechanisms of 3-MA in DE treatment. Results: Network pharmacological analysis identified two key targets of 3-MA in DE modulation: AKT and GSK3β. Molecular docking confirmed a strong binding affinity between 3-MA and AKT/GSK3β. In animal experiments, 3-MA significantly reduced blood glucose levels in diabetic mice, ameliorated learning and memory deficits, and preserved hippocampal neuronal integrity. Furthermore, we found that 3-MA inhibited apoptosis by regulating the expression of Bax and BCL-2. Notably, 3-MA also downregulated the expression of amyloid precursor protein (APP) and Tau while enhancing the expression of phosphorylated AKT and GSK-3β. Conclusions: Our findings may contribute to elucidating the therapeutic mechanisms of 3-MA in diabetic microangiopathy and provide potential therapeutic targets through activation of the AKT/GSK-3β pathway.

Smart self-healing hydrogel wound dressings for diabetic wound treatment

Diabetic wounds are difficult to treat clinically because they heal poorly, often leading to severe complications such as infections and amputations. Hydrogels with smart self-healing properties show great promise for treating diabetic wounds. These hydrogels are capable of continuously and dynamically responding to changes in the wound environment, feature improved mechanical qualities and the capacity to self-heal damage. We explore the latest developments in smart self-healing hydrogels for diabetic wound healing in this review. First, we systematically summarize the obstacles in treating diabetic wounds. We then highlighted the significance of smart self-healing hydrogels, explaining their stimulus-responsive mechanisms and self-healing design approaches, along with their applications in addressing these challenges. Finally, we discussed the unresolved obstacles and potential avenues for future research. We anticipate that this review will facilitate the continued refinement of smart self-healing hydrogels for diabetic wound dressings, aiming for broader clinical adoption.

Maladaptive Peripheral Ketogenesis in Schwann Cells Mediated by CB1R Contributes to Diabetic Neuropathy

Diabetic peripheral neuropathy (DPN) is the most common complication of diabetes. Although studies have previously investigated metabolic disruptions in the peripheral nervous system (PNS), the exact metabolic mechanisms underlying DPN remain largely unknown. Herein, a specific form of metabolic remodeling involving aberrant ketogenesis within Schwann cells (SCs) in streptozotocin (STZ)-induced type I diabetes mellitus is identified. The PNS adapts poorly to such aberrant ketogenesis, resulting in disrupted energy metabolism, mitochondrial damage, and homeostatic decompensation, ultimately contributing to DPN. Additionally, the maladaptive peripheral ketogenesis is highly dependent on the cannabinoid type-1 receptor (CB1R)-Hmgcs2 axis. Silencing CB1R reprogrammed the metabolism of SCs by blocking maladaptive ketogenesis, resulting in rebalanced energy metabolism, reduced histopathological changes, and improved neuropathic symptoms. Moreover, this metabolic reprogramming can be induced pharmacologically using JD5037, a peripheral CB1R blocker. These findings revealed a new metabolic mechanism underlying DPN, and promoted CB1R as a promising therapeutic target for DPN.

Macrophages protect against sensory axon loss in peripheral neuropathy

Peripheral neuropathy is a common complication of type 2 diabetes, which is strongly associated with obesity1, causing sensory loss and, in some patients, neuropathic pain2,3. Although the onset and progression of diabetic peripheral neuropathy is linked with dyslipidaemia and hyperglycaemia4, the contribution of inflammation to peripheral neuropathy pathogenesis has not been investigated. Here we used a high-fat, high-fructose diet (HFHFD), which induces obesity and prediabetic metabolic changes, to study the onset of peripheral neuropathy. Mice fed the HFHFD developed persistent heat hypoalgesia after 3 months, but a reduction in epidermal skin nerve fibre density manifested only at 6 months. Using single-cell sequencing, we found that CCR2+ macrophages infiltrate the sciatic nerves of HFHFD-fed mice well before axonal degeneration is detectable. These infiltrating macrophages share gene expression similarities with nerve-crush-induced macrophages5 and express neurodegeneration-associated microglial marker genes6, although there is no axon loss or demyelination. Inhibiting the macrophage recruitment by genetically or pharmacologically blocking CCR2 signalling resulted in more severe heat hypoalgesia and accelerated skin denervation, as did deletion of Lgals3, a gene expressed in recruited macrophages. Recruitment of macrophages into the peripheral nerves of obese prediabetic mice is, therefore, neuroprotective, delaying terminal sensory axon degeneration by means of galectin 3. Potentiating and sustaining early neuroprotective immune responses in patients could slow or prevent peripheral neuropathy.

Hippocampal P2X4 receptor induces type 1 diabetes rats with neuropathic pain through microglial-derived neuroinflammation and neuronal damage

Diabetic neuropathic pain (DNP) is a serious complication of diabetes, characterized by spontaneous burning pain, hyperalgesia or allodynia, and is associated with severely reduced quality of life. The purinergic P2X4 receptor (P2X4R) plays an essential role in neuropathic pain. In this study, we investigated the roles of hippocampal P2X4R in type 1 diabetes (T1D) rats with DNP. The reduced body weight, elevated blood glucose, and reduced mechanical withdrawal threshold (MWT) were manifested in DNP rats. The increased hippocampal P2X4R enhanced the release of TNF-α, IL-1β, IL-6, which may be related to activated microglia, thereby inducing the development of DNP, and these changes were attenuated by P2X4R antagonist. Our findings suggest that in the state of T1D, hippocampal P2X4R was elevated and enhanced reactive microglia, thereby aggravating the release of pro-inflammatory cytokines and neuronal damage to aggravate hyperalgesia.

Dual-responsive stem cell microspheres modified with BDNF for enhanced neural repair in diabetic erectile dysfunction

We previously established an effective method to ameliorate erectile dysfunction (ED) using intracavernous injection (ICI) of mesenchymal stem cell (MSC) microspheres. However, the expression of a key neurotrophic factor, brain-derived neurotrophic factor (BDNF), was low in both MSCs and MSC microspheres, restricting the associated neural repair. Based on the hypoxia and oxidative stress microenvironments within cell spheroids and lesion areas, BDNF-expressing nanocomplexes that are dual-responsive to hypoxia and reactive oxygen species were designed to modify MSCs, achieving high BDNF expression in MSC spheroids. Using the pelvic ganglion as an in vitro model, conditioned medium derived from stimuli-responsive MSC microspheres (SRMs) significantly promoted the growth of axons and alleviated the death of neural and smooth muscle cells. In rats with diabetes-induced ED, SRMs that underwent ICI effectively remained in the penis, demonstrating a potent therapeutic outcome. Penile erectile function, smooth muscle content, and neuropathological changes improved after treatment with SRMs compared to unmodified MSCs.

Neuropathy and the metabolic syndrome

Obesity and the metabolic syndrome (MetS) are major global health challenges that contribute significantly to the rising prevalence of type 2 diabetes (T2D) and neuropathy. Neuropathy, a common and disabling complication of T2D, is characterized by progressive distal-to-proximal axonal degeneration, driven in part by mitochondrial dysfunction in both neurons and axons. Recent evidence points to the toxic effects of saturated fatty acids on peripheral nerve health, with studies demonstrating that these fats impair mitochondrial function and bioenergetics, leading to distal axonal loss. Conversely, monounsaturated fatty acids are found to be neuroprotective, restoring mitochondrial function and preventing neuropathy. These findings suggest that dietary factors play a crucial role in the pathogenesis of neuropathy associated with metabolic dysregulation and emphasize the need for lifestyle interventions and therapies that target these newly identified mechanisms.

The Impact of SGLT-2 Inhibitors on Hydroxyl Radical Markers and Diabetic Neuropathy: A Short-Term Clinical Study

Beyond their metabolic effect, sodium-glucose cotransporter-2 (SGLT-2) inhibitors reduce the risk of heart failure and have cardiovascular and nephroprotective effects, yet their exact mechanism of action remains unclear. This prospective study included 40 patients with type 2 diabetes whose physician initiated SGLT-2 inhibitor therapy. Prior to and 4 weeks after the initiation of SGLT-2 inhibitors, in addition to routine clinical and laboratory measurements, hydroxyl free radical and neuropathic evaluations were performed. Body weight, body mass index (BMI), fasting glucose, fructosamine, and albuminuria decreased significantly, whereas red blood cell (RBC) count, hemoglobin, hematocrit, mean corpuscular volume (MCV), and platelet count increased significantly. Urinary o-tyrosine/p-tyrosine and (m-tyrosine+o-tyrosine)/p-tyrosine ratios were significantly reduced, suggesting diminished hydroxyl free radical production. Patients with neuropathy, identified by abnormal baseline current perception threshold (CPT) values, showed significant improvements. Significant correlations between RBCs, platelet parameters, albuminuria, and hydroxyl free radical markers disappeared after SGLT-2 treatment and changes in hydroxyl free radical markers correlated positively with CPT changes. Our results suggest that short-term SGLT-2 inhibition recalibrates metabolic, hematologic, renal, and neuropathic endpoints simultaneously, presumably through attenuating abnormal ortho- and meta-tyrosine incorporation into signaling proteins. Further studies are required to confirm long-term durability and examine whether additional strategies, such as supplementation of the physiological p-tyrosine, could amplify these benefits.

Longitudinal Metabolomics in Amyotrophic Lateral Sclerosis Implicates Impaired Lipid Metabolism

OBJECTIVE

Amyotrophic lateral sclerosis (ALS) is a fatal neurodegenerative disease characterized by altered metabolome and energy homeostasis, manifesting with body mass index changes and hypermetabolism-both prognostic of disease progression and survival. The cross-sectional ALS metabolome has been characterized, but longitudinal correlations to functional decline are lacking.

METHODS

We longitudinally evaluated metabolomes from ALS plasma and terminal postmortem spinal cord and brain motor cortex tissue. We constructed 3 plasma models. A linear mixed effects model correlated all metabolite levels across all timepoints to their corresponding functional scores. An interaction model predicted a longitudinal change in function from baseline metabolites, whereas a progression model identified metabolites linked to a 20% or 50% drop in function. In postmortem samples, differential metabolites in onset versus second spinal cord segments served as a surrogate of disease progression. Mendelian randomization assessed potential causality from metabolites.

RESULTS

In plasma, all models primarily selected lipid metabolites and sub-pathways, in addition to amino acids, xenobiotics, and various less frequently selected pathways. Among lipids, fatty acids and sphingomyelins were predominant, along with plasmalogens, phosphatidylcholines, and lysophospholipids. Sex interaction findings were nominal. In the spinal cord, sphingomyelin and long-chain saturated and monounsaturated fatty acids were more abundant in the onset segment tissue, whereas phosphatidylcholines and phosphatidylethanolamines were less abundant. Mendelian randomization suggested that impaired carnitine and short chain acylcarnitine metabolism may be genetically determined in ALS, along with various antioxidant derivatives.

INTERPRETATION

Our findings suggest metabolomic changes primarily involving different lipid classes and carnitine metabolism may underscore ALS severity and progression. ANN NEUROL 2025.

Dietary Fatty Acid Composition Alters Gut Microbiome in Mice with Obesity-Induced Peripheral Neuropathy

BACKGROUND

Peripheral neuropathy (PN), a complication of diabetes and obesity, progresses through a complex pathophysiology. Lifestyle interventions to manage systemic metabolism are recommended to prevent or slow PN, given the multifactorial risks of diabetes and obesity. A high-fat diet rich in saturated fatty acids (SFAs) induces PN, which a diet rich in monounsaturated fatty acids (MUFAs) rescues, independent of weight loss, suggesting factors beyond systemic metabolism impact nerve health. Interest has grown in gut microbiome mechanisms in PN, which is characterized by a distinct microbiota signature that correlates with sciatic nerve lipidome.

METHODS

Herein, we postulated that SFA- versus MUFA-rich diet would impact gut microbiome composition and correlate with PN development. To assess causality, we performed fecal microbiota transplantation (FMT) from donor mice fed SFA- versus MUFA-rich diet to lean recipient mice and assessed metabolic and PN phenotypes.

RESULTS

We found that the SFA-rich diet altered the microbiome community structure, which the MUFA-rich diet partially reversed. PN metrics correlated with several microbial families, some containing genera with feasible mechanisms of action for microbiome-mediated effects on PN. SFA and MUFA FMT did not impact metabolic phenotypes in recipient mice although SFA FMT marginally induced motor PN.

CONCLUSIONS

The involvement of diet-mediated changes in the microbiome on PN and gut-nerve axis may warrant further study.

Aspirin-triggered lipoxin A4 reduces neuropathic pain and anxiety-like behaviours in male diabetic rats: antinociceptive enhancement by cannabinoid receptor agonists

Neuropathy is the most common complication of diabetes, leading to painful symptoms like hyperalgesia. Current treatments for diabetic painful neuropathy often prove inadequate, necessitating the exploration of new pharmacological approaches. Therefore, this study aimed to investigate the potential antinociceptive effect of aspirin-triggered lipoxin A4 (ATL), a specialized pro-resolving lipid mediator, when administered alone or in combination with cannabinoid agonists, to alleviate diabetic neuropathic pain. Mechanical hyperalgesia in the hindpaws of streptozotocin (STZ)-induced diabetic (DBT) rats was assessed using the electronic Von Frey test (VFT), before diabetes induction and for up to 32 days after STZ administration and intraperitoneal ATL (0.3, 1, 3, 10, or 30 ng/rat) treatment, alone or in combination with intrathecal CB1 or CB2 receptor agonists (ACEA or JWH-133, respectively; 10 or 30 μg/rat). The effect of ATL treatment on locomotor activity and anxious or depressive-like behaviors was also evaluated. In comparison to control normoglycemic rats, control DBT rats developed: 1) mechanical hyperalgesia; 2) increase in anxious and depressive-like behaviors. ATL treatment attenuated mechanical hyperalgesia in DBT rats both acutely (at 30 ng) and cumulatively (at doses of 1, 3, 10, or 30 ng), without compromising locomotor activity. The antinociceptive effect of ATL (at 1 or 3 ng) was augmented when combined with ACEA or JWH-133 treatments (only at a dose of 30 μg/rat). While ATL treatment alone reduced anxious-like behavior in DBT rats, it did not affect depressive-like behavior. These findings underscore the therapeutic potential of ATL, in diabetic complications, suggesting a possible interaction with the endocannabinoid system.

Following changes in brain structure and function with multimodal MRI in a year-long prospective study on the development of Type 2 diabetes

Aims

To follow disease progression in a rat model of Type 2 diabetes using multimodal MRI to assess changes in brain structure and function.

Material and methods

Female rats (n = 20) were fed a high fat/high fructose diet or lab chow starting at 90 days of age. Diet fed rats were given streptozotocin to compromise pancreatic beta cells, while chow fed controls received vehicle. At intervals of 3, 6, 9, and 12 months, rats were tested for changes in behavior and sensitivity to pain. Brain structure and function were assessed using voxel based morphometry, diffusion weighted imaging and functional connectivity.

Results

Diet fed rats presented with elevated plasma glucose levels as early as 3 months and a significant gain in weight by 6 months as compared to controls. There were no significant changes in cognitive or motor behavior over the yearlong study but there was a significant increase in sensitivity to peripheral pain in diet fed rats. There were region specific decreases in brain volume e.g., basal ganglia, thalamus and brainstem in diet fed rats. These same regions showed elevated measures of water diffusivity evidence of putative vasogenic edema. By 6 months, widespread hyperconnectivity was observed across multiple brain regions. By 12 months, only the cerebellum and hippocampus showed increased connectivity, while the hypothalamus showed decreased connectivity in diet fed rats.

Conclusions

Noninvasive multimodal MRI identified site specific changes in brain structure and function in a yearlong longitudinal study of Type 2 diabetes in rats. The identified diabetic-induced neuropathological sites may serve as biomarkers for evaluating the efficacy of novel therapeutics.

Metabolomics in Pathogenic Pathways and Targeted Therapies for Diabetic Neuropathy: A Comprehensive Review

INTRODUCTION AND OBJECTIVE

This literature review aims to provide an overview of the progress in metabolomic assessment in animal and cell models and in humans with diabetic neuropathy (DN).

METHODS

Metabolomics has emerged as an important approach for investigating, identifying, and describing biomarkers related to DN. None has yet been validated for use in clinical practice.

RESULTS

DN induced significant alterations in energy metabolism and carbohydrates, lipids, amino acids, peptides, and proteins. Several treatments for DN, evaluated using metabolomics, were proved to have promising results.

CONCLUSIONS

The ideal metabolite or set of metabolites that could be used as biomarkers should identify patients with diabetes prone to develop DN or those prone to progress to severe forms of sensory loss, associated with risk of ulcerations and amputation. Another potential use of a metabolite might be as an indicator of treatment response in clinical trials using agents with potential disease-modifying properties.

Diabetes Mellitus Impairs Blood-Brain Barrier Integrality and Microglial Reactivity

Diabetes mellitus (DM), a chronic metabolic disorder that adversely affects the blood-brain barrier (BBB) and microglial function in the central nervous system (CNS), contributing to neuronal damage and neurodegenerative diseases. However, the underlying molecular mechanisms linking diabetes to BBB dysfunction and microglial dysregulation remain poorly understood. Here, we assessed the impacts of diabetes on BBB and microglial reactivity and investigated its mechanisms. We found diabetes severely disrupted the BBB integrity and microglial response to vascular injury. We also revealed a potential relationship between BBB disruption and impaired microglial function, whereby increasing BBB permeability led to a downregulation of microglial P2RY12 expression, thereby impairing microglial protection against cerebrovascular injury. Understanding these mechanisms may contribute to the developing of therapeutic strategies for diabetes-related neurological complications.

Effect of Advillin Knockout on Diabetic Neuropathy Induced by Multiple Low Doses of Streptozotocin

ABSTRACT

Advillin is an actin-binding protein involved in regulating the organization of actin filaments and the dynamics of axonal growth cones. In mice, advillin is exclusively expressed in somatosensory neurons, ubiquitously expressed in all neuron subtypes during neonatal ages and particularly enriched in isolectin B4-positive (IB4 + ) non-peptidergic neurons in adulthood. We previously showed that advillin plays a key role in axon regeneration of somatosensory neurons during peripheral neuropathy. Mice lacking advillin lost the ability to recover from neuropathic pain induced by oxaliplatin, chronic compression of the sciatic nerve, and experimental autoimmune encephalitis. However, the role of advillin in painful diabetic neuropathy remains unknown. Diabetic neuropathy, a prevalent complication of types 1 and 2 diabetes mellitus, poses significant treatment challenges because of the limited efficacy and adverse side effects of current analgesics. Here we probed the effect of advillin knockout on neuropathic pain in a diabetic mouse model induced by multiple low doses of streptozotocin (STZ). STZ-induced cold allodynia was resolved in 8 weeks in wild-type ( Avil +/+ ) mice but could last more than 30 weeks in advillin-knockout ( Avil -/- ) mice. Additionally, Avi -/- but not Avil +/+ mice showed STZ-induced mechanical hypersensitivity of muscle. Consistent with the prolonged and/or worsened STZ-induced neuropathic pain, second-line coping responses to pain stimuli were greater in Avil -/- than Avil +/+ mice. On analyzing intraepidermal nerve density, STZ induced large axon degeneration in the hind paws but with distinct patterns between Avil +/+ and Avil -/- mice. We next probed whether advillin knockout could disturb capsaicin-induced axon regeneration ex vivo because capsaicin is clinically used to treat painful diabetic neuropathy by promoting axon regeneration. In a primary culture of dorsal root ganglion cells, 10-min capsaicin treatment selectively promoted neurite outgrowth of IB4 + neurons in Avil +/+ but not Avil -/- groups, which suggests that capsaicin could reprogram the intrinsic axonal regeneration by modulating the advillin-mediated actin dynamics. In conclusion, advillin knockout prolonged STZ-induced neuropathic pain in mice, which may be associated with the impaired intrinsic capacity of advillin-dependent IB4 + axon regeneration.

The global and regional burden of diabetic peripheral neuropathy

Diabetic peripheral neuropathy (DPN) is length-dependent peripheral nerve damage arising as a complication of type 1 or type 2 diabetes in up to 50% of patients. DPN poses a substantial burden on patients, who can experience impaired gait and loss of balance, predisposing them to falls and fractures, and neuropathic pain, which is frequently difficult to treat and reduces quality of life. Advanced DPN can lead to diabetic foot ulcers and non-healing wounds that often necessitate lower-limb amputation. From a socioeconomic perspective, DPN increases both direct health-care costs and indirect costs from loss of productivity owing to neuropathy-related disability. In this Review, we highlight the importance of understanding country-specific and region-specific variations in DPN prevalence to inform public health policy and allocate resources appropriately. We also explore how identification of DPN risk factors can guide treatment and prevention strategies and aid the development of health-care infrastructure for populations at risk. We review evidence that metabolic factors beyond hyperglycaemia contribute to DPN development, necessitating a shift from pure glycaemic control to multi-targeted metabolic control, including weight loss and improvements in lipid profiles.

An Overview on Diabetic Neuropathy

The term "Diabetic neuropathy" refers to a collection of clinical and subclinical symptoms caused by problems with the peripheral nervous system. Diabetes, which affects approximately 381 million people worldwide, is the source of dysfunction due to the emergence of microvascular complications. It is anticipated that in the next ten years, Diabetic neuropathy will manifest in about 50% of patients who are currently diagnosed with diabetes. Clinical diagnosis can be established by getting a thorough patient history and exploring the symptoms to rule out alternative causes. Although distal symmetrical polyneuropathy, or just, is the most common and well-researched variant of the disorder, this review will concentrate on it. The multifactorial pathogenesis is linked to various inflammatory, vascular, metabolic, and neurodegenerative illnesses. The three fundamental molecular alterations that lead to the development of diabetic neuropathic pain are oxidative stress, endothelial dysfunction, and chronic inflammation. These three elements are crucial in the development of polyneuropathy because their combination might result in direct axonal damage and nerve ischemia. The purpose of this article was to provide a narrative review of diabetic neuropathy. We provide an overview of the most recent data on biomarkers, the pathogenesis of the illness, the most recent epidemiology of diabetic neuropathy, and the existing screening and diagnosis outcome measures used in both clinical and research contexts.

A reinforcement learning approach to effective forecasting of pediatric hypoglycemia in diabetes I patients using an extended de Bruijn graph

Pediatric diabetes I is an endemic and an especially difficult disease; indeed, at this point, there does not exist a cure, but only careful management that relies on anticipating hypoglycemia. The changing physiology of children producing unique blood glucose signatures, coupled with inconsistent activities, e.g., playing, eating, napping, makes "forecasting" elusive. While work has been done for adult diabetes I, this does not successfully translate for children. In the work presented here, we adopt a reinforcement approach by leveraging the de Bruijn graph that has had success in detecting patterns in sequences of symbols-most notably, genomics and proteomics. We translate a continuous signal of blood glucose levels into an alphabet that then can be used to build a de Bruijn, with some extensions, to determine blood glucose states. The graph allows us to "tune" its efficacy by computationally ignoring edges that provide either no information or are not related to entering a hypoglycemic episode. We can then use paths in the graph to anticipate hypoglycemia in advance of about 30 minutes sufficient for a clinical setting and additionally find actionable rules that accurate and effective. All the code developed for this study can be found at: https://github.com/KurbanIntelligenceLab/dBG-Hypoglycemia-Forecast .

Advances of traditional Chinese medicine preclinical mechanisms and clinical studies on diabetic peripheral neuropathy

CONTEXT

Diabetic peripheral neuropathy (DPN) results in an enormous burden and reduces the quality of life for patients. Considering there is no specific drug for the management of DPN, traditional Chinese medicine (TCM) has increasingly drawn attention of clinicians and researchers around the world due to its characteristics of multiple targets, active components, and exemplary safety.

OBJECTIVE

To summarize the current status of TCM in the treatment of DPN and provide directions for novel drug development, the clinical effects and potential mechanisms of TCM used in treating DPN were comprehensively reviewed.

METHODS

Existing evidence on TCM interventions for DPN was screened from databases such as PubMed, the Cochrane Neuromuscular Disease Group Specialized Register (CENTRAL), and the Chinese National Knowledge Infrastructure Database (CNKI). The focus was on summarizing and analyzing representative preclinical and clinical TCM studies published before 2023.

RESULTS

This review identified the ameliorative effects of about 22 single herbal extracts, more than 30 herbal compound prescriptions, and four Chinese patent medicines on DPN in preclinical and clinical research. The latest advances in the mechanism highlight that TCM exerts its beneficial effects on DPN by inhibiting inflammation, oxidative stress and apoptosis, endoplasmic reticulum stress and improving mitochondrial function.

CONCLUSIONS

TCM has shown the power latent capacity in treating DPN. It is proposed that more large-scale and multi-center randomized controlled clinical trials and fundamental experiments should be conducted to further verify these findings.

Pharmacological Effects of Paeonia lactiflora Focusing on Painful Diabetic Neuropathy

Painful diabetic neuropathy (PDN) is a highly prevalent complication in patients suffering from diabetes mellitus. Given the inadequate pain-relieving effect of current therapies for PDN, there is a high unmet medical need for specialized therapeutic options. In traditional Chinese medicine (TCM), various herbal formulations have been implemented for centuries to relieve pain, and one commonly used plant in this context is Paeonia lactiflora (P. lactiflora). Here, we summarize the chemical constituents of P. lactiflora including their pharmacological mechanisms-of-action and discuss potential benefits for the treatment of PDN. For this, in silico data, as well as preclinical and clinical studies, were critically reviewed and comprehensively compiled. Our findings reveal that P. lactiflora and its individual constituents exhibit a variety of pharmacological properties relevant for PDN, including antinociceptive, anti-inflammatory, antioxidant, and antiapoptotic activities. Through this multifaceted and complex combination of various pharmacological effects, relevant hallmarks of PDN are specifically addressed, suggesting that P. lactiflora may represent a promising source for novel therapeutic approaches for PDN.

An advanced chitosan based sponges dressing system with antioxidative, immunoregulation, angiogenesis and neurogenesis for promoting diabetic wound healing

Promoting wound nerve regeneration and synchronously initiating angiogenesis are critical factors in the healing process of diabetic wounds. However, existing research on diabetic wounds mainly focuses on angiogenesis, bacterial infection and reactive oxygen species, often failing to coordinate neurogenesis and angiogenesis. To coordinate the symbiosis of nerves and blood vessels in the diabetic wounds, we successfully designed a multifunctional chitosan (CS)-based sponges by regulating the structure of CS specifically for diabetic wound healing. This sponge, which facilitates effective exudate transfer and modulates the wound microenvironment, was constructed using hydroxybutyl CS grafted with thioctic acid (TA), named as HCT sponge. When applied in a humid environment, the hydrophobic side chains of the HCT sponge interact with self-assembled hydrophobic domains, forming gel-sponge composite. Experimental results showed that the adhesion strength of the HCT sponge to wet porcine skin was 70.3 kPa. Additionally, the sponge exhibited favorable degradability, cytocompatibility and antioxidant properties. As it is shown in the experiments in vitro, sponge can not only promote cell proliferation, migration, and blood vessel formation, but also promote M2 macrophage polarization. Moreover, the rat liver and femoral artery injury model validated that the HCT sponge can effectively treat heavy bleeding from wounds efficacy through quickly sealing wounds and the formation of multiple hemostatic dams. In vivo studies indicated that the HCT sponge significantly accelerated the diabetic wound healing process compared to the recombinant bovine basic fibroblast growth factor gel, achieving a better recovery from the HCT sponge after 15 days. Pathological results show that the designed novel sponge holds considerable promise for treating diabetic wound, allowing regenerative neurogenesis and angiogenesis at the wound site, which provides a significant potential for further improving clinical applications.

Efficacy and Safety of Agomelatine in Depressed Patients with Diabetes: A Systematic Review and Meta-Analysis

Major depressive disorder (MDD) and diabetes mellitus (DM) remain among the most prevalent diseases and the most significant challenges faced by medicine in the 21st century. The frequent co-occurrence and bidirectional relationship between the two conditions necessitates the identification of treatment strategies that benefit both. The purpose of this study was to systematically review and meta-analyze data on the efficacy and safety of agomelatine (AGO) in the treatment of patients with depression with comorbid diabetes to explore its potential mechanism of action in both diseases and its impact on diabetic parameters. Following PRISMA guidelines, a total of 11 studies were identified, both preclinical and clinical trials. Agomelatine has shown great potential as a treatment option for patients with diabetes and comorbid depression and anxiety. In addition to improving depressive and anxiety symptoms, it is also beneficial in glycemic control. A meta-analysis demonstrated a statistically significant reduction in glycated hemoglobin (HbA1C) and fasting blood glucose (FBG) levels following AGO administration over a period of 8-16 weeks. The administration of agomelatine was found to result in a significantly greater reduction in HbA1C than that observed with the selective serotonin reuptake inhibitor (SSRI) medications (namely fluoxetine, sertraline, and paroxetine) during 12-16 weeks of therapy. Furthermore, AGO has been found to be at least as effective as SSRIs in reducing depressive symptoms and more effective than SSRIs in reducing anxiety symptoms. The safety of such treatment is similar to SSRIs; no severe adverse events were reported, and the incidence of some side effects, such as insomnia and sexual dysfunction, are even less often reported. Particularly promising is also its potential action in improving some diabetic complications reported in preclinical trials. This might be through mechanisms involving the reduction in oxidative stress, anti-inflammatory effects, and potentially noradrenergic or NMDA receptor modulation. Further clinical studies on larger sample sizes, as well as elucidating its mechanisms of action, especially in the context of diabetic complications, are needed. Research should also focus on identifying the patient subpopulations most likely to benefit from agomelatine treatment.

Assessing the diagnostic utility of urinary albumin-to-creatinine ratio as a potential biomarker for diabetic peripheral neuropathy in type 2 diabetes mellitus patients

BACKGROUND AND AIMS

Diabetic peripheral neuropathy (DPN) and diabetic nephropathy (DN) both have microcirculation dysfunction. Urinary albumin-to-creatinine ratio (UACR) is a biomarker for DN. We aimed to explore the links between DPN and UACR in patients with type 2 diabetes mellitus (T2DM).

METHODS

A total of 195 T2DM patients were defined as Control or DPN group. Clinical parameters were compared, and the association between HbA1c (or UACR) and DPN was analyzed. Risk factors for DPN were observed, and the diagnostic values of HbA1c and UACR were assessed.

RESULTS

Compared with 104 participants without DPN, 91 individuals with DPN exhibited higher HbA1c and UACR levels. In all patients, increased HbA1c and UACR were identified as risk factors for DPN in individuals with T2DM. Moreover, increased HbA1c was a risk factor for DPN in volunteers without DN, whereas elevated UACR was determined as a risk factor for DPN in participants with DN. The cut-off point for HbA1c (7.65%) in patients without DN had a sensitivity of 86.0% and specificity of 44.6%, while the cut-off point for UACR (196.081 mg/g) in patients with DN had a sensitivity of 52.9% and specificity of 76.2%.

CONCLUSION

Elevated HbA1c and UACR levels are risk factors for DPN and may serve as potential biomarkers for DPN in T2DM patients.

Dietary patterns and diabetic microvascular complications risk: a Mendelian randomization study of European ancestry

Purpose

Previous observational studies about the link between dietary factors and diabetic microvascular complications (DMCs) is controversial. Thus, we systemically assessed the potential causal relationship between diet and DMCs risk using Mendelian randomization (MR) methods.

Methods

We used genome-wide association studies (GWAS) statistics to estimate the causal effects of 17 dietary patterns on three common DMCs in European. Summary statistics on dietary intakes were obtained from the UK biobank, and data on DMCs [diabetic retinopathy (DR), diabetic nephropathy (DN), and diabetic neuropathy (DNP)] were obtained from the FinnGen Consortium. A two-sample MR (TSMR) was conducted to explore the causal relationships of dietary habits with DMCs. In addition, multivariable MR analysis (MVMR) was performed to adjust for traditional risk factors for eating habits, and evaluated the direct or indirect effects of diet on DMCs.

Results

TSMR analysis revealed that salad/raw vegetable intake (odd ratio [OR]: 2.830; 95% confidence interval [CI]: 1.102-7.267; p = 0.0306) and fresh fruit intake (OR: 2.735; 95% CI: 1.622-4.611; p = 0.0002; false discovery rate [FDR] = 0.0082) increased the risk of DR, whereas cheese intake (OR: 0.742; 95% CI: 0.563-0.978; p = 0.0339) and cereal intake (OR: 0.658; 95% CI: 0.444-0.976; p = 0.0374) decreased the risk of DR. Salad/raw vegetable (OR: 6.540; 95% CI: 1.061-40.300; p = 0.0430) and fresh fruit consumption (OR: 3.573; 95% CI: 1.263-10.107; p = 0.0164) are risk factors for DN, while cereal consumption (OR: 0.380; 95% CI: 0.174-0.833; p = 0.0156) is the opposite. And genetically predicted higher pork intake increased the risk of DNP (OR: 160.971; 95% CI: 8.832-2933.974; p = 0.0006; FDR = 0.0153). The MVMR analysis revealed that cheese intake may act as an independent protective factor for DR development. Moreover, fresh fruit intake, salad/raw vegetable intake and pork intake may be independent risk factors for DR, DN and DNP, respectively. Other causal associations between dietary habits and DMCs risk may be mediated by intermediate factors.

Conclusion

This causal relationship study supports that specific dietary interventions may reduce the risk of DMCs.

Characterization of the Metabolic Proteome of Serum From Patients With Diabetic Distal Symmetric Polyneuropathy

AIMS

The pathophysiological of diabetic distal symmetric polyneuropathy (DSPN) remains to be elucidated and there are no diagnostic or prognostic biomarkers for the condition. In this explorative proteomic study, metabolic proteome profiling of serum in patients with/without DSPN was analyzed. We aimed to discover proteins with different abundance ranges through proximity extension assay (PEA) technology.

METHODS

Temperature quantitative sensory testing (QST) and electromyography (EMG) were used to access the small- and large-fiber function of all participants, respectively. The metabolic proteome profile of serum was analyzed using PEA technology (Olink Target 96 METABOLISM panel).

RESULTS

We evaluated serum from patients without DSPN (n = 27), with small-fiber neuropathy (SFN, n = 25) and with mixed small- and large-fiber neuropathy (MSLFN, n = 24). Fifteen proteins, which were especially related to immune response, insulin resistance, and lipid metabolism, were significantly different between patients without DSPN and with MSLFN. Besides, seven proteins, especially related to extracellular structure organization, were significantly different between serum from patients with SFN and with MSLFN. What's more, serum from patients without DSPN showed that three proteins, related to immune response, altered significantly compared to serum from patients with SFN.

CONCLUSIONS

This was the first study that characterized the metabolic proteomic profile of serum in DSPN patients by analyzing a panel of 92 metabolic proteins using PEA technology.

High-Intensity Interval Training, Caloric Restriction, or Their Combination Have Beneficial Effects on Metabolically Acquired Peripheral Neuropathy

Peripheral neuropathy (PN) is a prevalent and debilitating complication of obesity, prediabetes, and type 2 diabetes, which remains poorly understood and lacks disease-modifying therapies. Fortunately, diet and/or exercise have emerged as effective treatment strategies for PN. Here, we examined the impact of caloric restriction (CR) and high-intensity interval training (HIIT) interventions, alone or combined (HIIT-CR), on metabolic and PN outcomes in high-fat diet (HFD) mice. HFD feeding alone resulted in obesity, impaired glucose tolerance, and PN. Peripheral nerves isolated from these mice also developed insulin resistance (IR). CR and HIIT-CR, but not HIIT alone, improved HFD-induced metabolic dysfunction. However, all interventions improved PN to similar extents. When examining the underlying neuroprotective mechanisms in whole nerves, we found that CR and HIIT-CR activate the fuel-sensing enzyme AMPK. We then performed complimentary in vitro work in Schwann cells, the glia of peripheral nerves. Treating primary Schwann cells with the saturated fatty acid palmitate to mimic prediabetic conditions caused IR, which was reversed by the AMPK activator, AICAR. Together, these results enhance our understanding of PN pathogenesis, the differential mechanisms by which diet and exercise may improve PN, and Schwann cell-specific contributions to nerve insulin signaling and PN progression.

ARTICLE HIGHLIGHTS

Jinmaitong alleviates diabetic neuropathic pain by inhibiting JAK2/STAT3 signaling in microglia of diabetic rats

ETHNOPHARMACOLOGICAL RELEVANCE

Jinmaitong (JMT) is a prescription of Traditional Chinese Medicine that is composed of 12 crude drugs. It has been used in the treatment of diabetic neuropathic pain (DNP) for more than 30 years.

AIM OF STUDY

Microglia are thought to play an important role in neuropathic pain. This study aimed to evaluate the protective effect of JMT against DNP and to investigate the underlying mechanisms in which the microglia and JAK2/STAT3 signaling pathway were mainly involved.

MATERIALS AND METHODS

The chemical composition of JMT was analyzed using liquid chromatography tandem mass spectrometry. The diabetes model was constructed using 11 to 12-week-old male Zucker diabetic fatty (ZDF) rat (fa/fa). The model rats were divided into 5 groups and were given JMT at three dosages (11.6, 23.2, and 46.4 g/kg, respectively, calculated as the crude drug materials), JAK inhibitor AG490 (positive drug, 10 μg/day), and placebo (deionized water), respectively, for eight weeks (n = 6). Meanwhile, Zucker lean controls (fa/+) were given a placebo (n = 6). Body weight was tested weekly and blood glucose was monitored every 2 weeks. The mechanical allodynia and heat hyperalgesia were assessed using mechanical withdrawal threshold (MWT) and thermal withdrawal latency (TWL) tests. After treatment, the microglia activation marker Iba-1, CD11B, CD68, neuroinflammatory mediators, and mediators of the JAK2/STAT3 signaling pathway were compared between different groups. The mRNA and protein levels of target genes were assessed by quantitative real-time PCR and Western Blot, respectively.

RESULTS

We found that JMT significantly inhibited the overactivation of microglia in spinal cords, and suppressed neuroinflammation of DNP model rats, thereby ameliorating neurological dysfunction and injuries. Furthermore, these effects of JMT could be attributed to the inhibition of the JAK2/STAT3 signaling pathway.

CONCLUSIONS

Our findings suggested that JMT effectively ameliorated DNP by modulating microglia activation via inhibition of the JAK2/STAT3 signaling pathway. The present study provided a basis for further research on the therapeutic strategies of DNP.

Type 2 diabetes mellitus in adults: pathogenesis, prevention and therapy

Type 2 diabetes (T2D) is a disease characterized by heterogeneously progressive loss of islet β cell insulin secretion usually occurring after the presence of insulin resistance (IR) and it is one component of metabolic syndrome (MS), and we named it metabolic dysfunction syndrome (MDS). The pathogenesis of T2D is not fully understood, with IR and β cell dysfunction playing central roles in its pathophysiology. Dyslipidemia, hyperglycemia, along with other metabolic disorders, results in IR and/or islet β cell dysfunction via some shared pathways, such as inflammation, endoplasmic reticulum stress (ERS), oxidative stress, and ectopic lipid deposition. There is currently no cure for T2D, but it can be prevented or in remission by lifestyle intervention and/or some medication. If prevention fails, holistic and personalized management should be taken as soon as possible through timely detection and diagnosis, considering target organ protection, comorbidities, treatment goals, and other factors in reality. T2D is often accompanied by other components of MDS, such as preobesity/obesity, metabolic dysfunction associated steatotic liver disease, dyslipidemia, which usually occurs before it, and they are considered as the upstream diseases of T2D. It is more appropriate to call "diabetic complications" as "MDS-related target organ damage (TOD)", since their development involves not only hyperglycemia but also other metabolic disorders of MDS, promoting an up-to-date management philosophy. In this review, we aim to summarize the underlying mechanism, screening, diagnosis, prevention, and treatment of T2D, especially regarding the personalized selection of hypoglycemic agents and holistic management based on the concept of "MDS-related TOD".

Nageotte nodules in human DRG reveal neurodegeneration in painful diabetic neuropathy

Diabetic neuropathy is frequently accompanied by pain and loss of sensation attributed to axonal dieback. We recovered dorsal root ganglia (DRGs) from 90 organ donors, 19 of whom had medical indices for diabetic painful neuropathy (DPN). Nageotte nodules, dead sensory neurons engulfed by non-neuronal cells, were abundant in DPN DRGs and accounted for 25% of all neurons. Peripherin-and Nav1.7-positive dystrophic axons invaded Nageotte nodules, forming small neuroma-like structures. Using histology and spatial sequencing, we demonstrate that Nageotte nodules are mainly composed of satellite glia and non-myelinating Schwann cells that express SPP1 and are intertwined with sprouting sensory axons originating from neighboring neurons. Our findings solve a 100-year mystery of the nature of Nageotte nodules linking these pathological structures to pain and sensory loss in DPN.

Xiaoke Bitong capsule alleviates inflammatory impairment via inhibition of the TNF signaling pathway to against diabetic peripheral neuropathy

BACKGROUND

Xiaoke Bitong capsule (XBC) is a crude herbal compound believed to tonify qi, improve blood circulation, and alleviate blood stasis. It has been used as an herbal formula for the prevention and treatment of diabetic peripheral neuropathy (DPN) under the guidance of traditional Chinese medicine (TCM). However, the pharmacological mechanisms by which XBC ameliorates DPN remain poorly understood. The interaction between pro-inflammatory factors and the activation of tumor necrosis factor (TNF) plays a critical role in the underlying mechanisms of DPN. XBC may protect against DPN through the regulation of the TNF pathway.

PURPOSE

Many studies show the association between DPN and nerve dysfunction, however, treatment options are limited. To identify specific therapeutic targets and active components of XBC that contribute to its anti-DPN effects, our study aimed to investigate the potential mechanism of action of XBC during the progression of DPN using a system pharmacology approach.

METHODS

An approach involving UPLC-Q-TOF/MS and network pharmacology was used to analyze the compositions, potential targets, and active pathways of XBC. Further, models of streptozocin (STZ) induced mouse and glucose induced RSC96 cells were established to explore the therapeutic effects of XBC. High glucose induced RSC96 cells were pretreated with small interfering RNA (siRNA) to identify potential therapeutic targets of DPN.

RESULTS

Seventy-one active compositions of XBC and five potential targets, including mitogen-activated protein kinase 8 (MAPK), interleukin-6 (IL-6), poly-ADP-ribose polymerase-1 (PARP1), vascular endothelial growth factor A (VEGFA), and transcription factor p65 (NF-κB), were considered as the potential regulators of DPN. In addition, the results revealed that the TNF signaling pathway was closely related to DPN. Moreover, DPN contributed to the decreased expressions of PI3K and AKT, increased TNF-α and IL-1β in RSC96 cells, which were both reversed by XBC or TNF-α siRNA.

CONCLUSION

XBC could protect against DPN by inhibiting the release of pro-inflammatory cytokines and regulating the activation of the TNF signaling pathway, further accelerating neurogenesis, and alleviating peripheral nerve lesions. Therefore, this study highlights the therapeutic value of XBC for DPN.

Diabetic neuropathy: A NRF2 disease?

The transcription factor nuclear factor erythroid 2-related factor 2 (NRF2) has multifarious action with its target genes having redox-regulating functions and being involved in inflammation control, proteostasis, autophagy, and metabolic pathways. Therefore, the genes controlled by NRF2 are involved in the pathogenesis of myriad diseases, such as cardiovascular diseases, metabolic syndrome, neurodegenerative diseases, autoimmune disorders, and cancer. Amidst this large array of diseases, diabetic neuropathy (DN) occurs in half of patients diagnosed with diabetes and appears as an injury inflicted upon peripheral and autonomic nervous systems. As a complex effector factor, NRF2 has entered the spotlight during the search of new biomarkers and/or new therapy targets in DN. Due to the growing attention for NRF2 as a modulating factor in several diseases, including DN, this paper aims to update the recently discovered regulatory pathways of NRF2 in oxidative stress, inflammation and immunity. It presents the animal models that further facilitated the human studies in regard to NRF2 modulation and the possibilities of using NRF2 as DN biomarker and/or as target therapy.

Nageotte nodules in human DRG reveal neurodegeneration in painful diabetic neuropathy

Diabetic neuropathy is frequently accompanied by pain and loss of sensation attributed to axonal dieback. We recovered dorsal root ganglia (DRGs) from 90 organ donors, 19 of whom had medical indices for diabetic painful neuropathy (DPN). Nageotte nodules, dead sensory neurons engulfed by non-neuronal cells, were abundant in DPN DRGs and accounted for 25% of all neurons. Peripherin-and Nav1.7-positive dystrophic axons invaded Nageotte nodules, forming small neuroma-like structures. Using histology and spatial sequencing, we demonstrate that Nageotte nodules are mainly composed of satellite glia and non-myelinating Schwann cells that express SPP1 and are intertwined with sprouting sensory axons originating from neighboring neurons. Our findings solve a 100-year mystery of the nature of Nageotte nodules linking these pathological structures to pain and sensory loss in DPN.

Systematic review of translational insights: Neuromodulation in animal models for Diabetic Peripheral Neuropathy

Diabetic Peripheral Neuropathy (DPN) is a prevalent and debilitating complication of diabetes, affecting a significant proportion of the diabetic population. Neuromodulation, an emerging therapeutic approach, has shown promise in the management of DPN symptoms. This systematic review aims to synthesize and analyze the current advancements in neuromodulation techniques for the treatment of DPN utilizing studies with preclinical animal models. A comprehensive search was conducted across multiple databases, including PubMed, Scopus, and Web of Science. Inclusion criteria were focused on studies utilizing preclinical animal models for DPN that investigated the efficacy of various neuromodulation techniques, such as spinal cord stimulation, transcranial magnetic stimulation, and peripheral nerve stimulation. The findings suggest that neuromodulation significantly alleviated pain symptoms associated with DPN. Moreover, some studies reported improvements in nerve conduction velocity and reduction in nerve damage. The mechanisms underlying these effects appeared to involve modulation of pain pathways and enhancement of neurotrophic factors. However, the review also highlights the variability in methodology and stimulation parameters across studies, highlighting the need for standardization in future research. Additionally, while the results are promising, the translation of these findings from animal models to human clinical practice requires careful consideration. This review concludes that neuromodulation presents a potentially effective therapeutic strategy for DPN, but further research is necessary to optimize protocols and understand the underlying molecular mechanisms. It also emphasizes the importance of bridging the gap between preclinical findings and clinical applications to improve the management of DPN in diabetic patients.

Pathological evaluation of the pathogenesis of diabetes mellitus and diabetic peripheral neuropathy

Currently, there are more than 10 million patients with diabetes mellitus in Japan. Therefore, the need to explore the pathogenesis of diabetes and the complications leading to its cure is becoming increasingly urgent. Pathological examination of pancreatic tissues from patients with type 2 diabetes reveals a decrease in the volume of beta cells because of a combination of various stresses. In human type 2 diabetes, islet amyloid deposition is a unique pathological change characterized by proinflammatory macrophage (M1) infiltration into the islets. The pathological changes in the pancreas with islet amyloid were different according to clinical factors, which suggests that type 2 diabetes can be further subclassified based on islet pathology. On the other hand, diabetic peripheral neuropathy is the most frequent diabetic complication. In early diabetic peripheral neuropathy, M1 infiltration in the sciatic nerve evokes oxidative stress or attenuates retrograde axonal transport, as clearly demonstrated by in vitro live imaging. Furthermore, islet parasympathetic nerve density and beta cell volume were inversely correlated in type 2 diabetic Goto-Kakizaki rats, suggesting that diabetic peripheral neuropathy itself may contribute to the decrease in beta cell volume. These findings suggest that the pathogenesis of diabetes mellitus and diabetic peripheral neuropathy may be interrelated.

Transcriptomic profiling of sciatic nerves and dorsal root ganglia reveals site-specific effects of prediabetic neuropathy

Peripheral neuropathy (PN) is a severe and frequent complication of obesity, prediabetes, and type 2 diabetes characterized by progressive distal-to-proximal peripheral nerve degeneration. However, a comprehensive understanding of the mechanisms underlying PN, and whether these mechanisms change during PN progression, is currently lacking. Here, gene expression data were obtained from distal (sciatic nerve; SCN) and proximal (dorsal root ganglia; DRG) injury sites of a high-fat diet (HFD)-induced mouse model of obesity/prediabetes at early and late disease stages. Self-organizing map and differentially expressed gene analyses followed by pathway enrichment analysis identified genes and pathways altered across disease stage and injury site. Pathways related to immune response, inflammation, and glucose and lipid metabolism were consistently dysregulated with HFD-induced PN, irrespective of injury site. However, regulation of oxidative stress was unique to the SCN while dysregulated Hippo and Notch signaling were only observed in the DRG. The role of the immune system and inflammation in disease progression was supported by an increase in the percentage of immune cells in the SCN with PN progression. Finally, when comparing these data to transcriptomic signatures from human patients with PN, we observed conserved pathways related to metabolic dysregulation across species, highlighting the translational relevance of our mouse data. Our findings demonstrate that PN is associated with distinct site-specific molecular re-programming in the peripheral nervous system, identifying novel, clinically relevant therapeutic targets.