Diabetic neuropathies

Diminished levels of insulin-like growth factor-1 may be a risk factor for peripheral neuropathy in type 2 diabetes patients

AIMS/INTRODUCTION

To investigate risk factors for diabetic peripheral neuropathy (DPN) and to explore the connection between insulin-like growth factor-1 (IGF-1) and DPN in individuals with type 2 diabetes.

MATERIALS AND METHODS

A total of 790 patients with type 2 diabetes participated in a cross-sectional study, divided into two groups: those with DPN (DPN) and those without DPN (non-DPN). Blood samples were taken to measure IGF-1 levels and other biochemical markers. Participants underwent nerve conduction studies and quantitative sensory testing.

RESULTS

Patients with DPN exhibited significantly lower levels of IGF-1 compared with non-DPN patients (P < 0.001). IGF-1 was positively correlated with the average amplitude of both motor (P < 0.05) and sensory nerves (P < 0.05), but negatively correlated with the vibration perception threshold (P < 0.05). No significant difference was observed between IGF-1 and nerve conduction velocity (P > 0.05), or the temperature detection threshold (P > 0.05). Multivariate regression analysis identified diabetes duration, HbA1c, and the low levels of IGF-1 as independent risk factors (P < 0.001). Receiver operating characteristic analysis determined that at 8 years duration of diabetes, 8.5% (69.4 mmol/mol) HbA1c and 120 ng/mL IGF-1, the optimal cut-off points, indicated DPN (P < 0.001).

CONCLUSIONS

A reduction of IGF-1 in patients with DPN suggests a potential protective role against axon injury in large fiber nerves of type 2 diabetes 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.

Feasibility of Multiparametric Perfusion Assessment in Diabetic Foot Ulcer Using Intravoxel Incoherent Motion and Blood Oxygenation-Level Dependent MRI

BACKGROUND

Patients with type-2 diabetes (T2DM) are at increased risk of developing diabetic foot ulcers (DFU) and experiencing impaired wound healing related to underlying microvascular disease.

PURPOSE

To evaluate the sensitivity of intra-voxel incoherent motion (IVIM) and blood oxygen level dependent (BOLD) MRI to microvascular changes in patients with DFUs.

STUDY TYPE

Case-control.

POPULATION

20 volunteers who were age and body mass index matched, including T2DM patients with DFUs (N = 10, mean age = 57.5 years), T2DM patients with controlled glycemia and without DFUs (DC, N = 5, mean age = 57.4 years) and healthy controls (HC, N = 5, mean age = 52.8 years).

FIELD STRENGTH/SEQUENCE

3T/multi-b-value IVIM and dynamic BOLD.

ASSESSMENT

Resting IVIM parameters were obtained using a multi-b-value diffusion-weighted imaging sequence and two IVIM models were fit to obtain diffusion coefficient (D), pseudo-diffusion coefficient (D*), perfusion fraction (f) and microvascular volume fraction (MVF) parameters. Microvascular reactivity was evaluated by inducing an ischemic state in the foot with a blood pressure cuff during dynamic BOLD imaging. Perfusion indices were assessed in two regions of the foot: the medial plantar (MP) and lateral plantar (LP) regions.

STATISTICAL TESTS

Effect sizes of group mean differences were assessed using Hedge's g adjusted for small sample sizes.

RESULTS

DFU participants exhibited elevated D*, f, and MVF values in both regions (g ≥ 1.10) and increased D (g = 1.07) in the MP region compared to DC participants. DC participants showed reduced f and MVF compared to HC participants in the MP region (g ≥ 1.06). Finally, the DFU group showed reduced tolerance for ischemia in the LP region (g = -1.51) and blunted reperfusion response in both regions (g < -2.32) compared to the DC group during the cuff-occlusion challenge.

DATA CONCLUSION

The combined use of IVIM and BOLD MRI shows promise in differentiating perfusion abnormalities in the feet of diabetic patients and suggests hyperperfusion in DFU patients.

LEVEL OF EVIDENCE

1 TECHNICAL EFFICACY: Stage 1.

Alpha-lipoic acid for diabetic peripheral neuropathy

BACKGROUND

Diabetic peripheral neuropathy (DPN) is a frequent complication in people living with type 1 or type 2 diabetes. There is currently no effective treatment for DPN. Although alpha-lipoic acid (ALA, also known as thioctic acid) is widely used, there is no consensus about its benefits and harms.

OBJECTIVES

To assess the effects of alpha-lipoic acid as a disease-modifying agent in people with diabetic peripheral neuropathy.

SEARCH METHODS

On 11 September 2022, we searched the Cochrane Neuromuscular Specialised Register, CENTRAL, MEDLINE, Embase, and two clinical trials registers. We also searched the reference lists of the included studies and relevant review articles for additional references not identified by the electronic searches.

SELECTION CRITERIA

We included randomised clinical trials (RCTs) that compared ALA with placebo in adults (aged 18 years or older) and that applied the study interventions for at least six months. There were no language restrictions.

DATA COLLECTION AND ANALYSIS

We used standard methods expected by Cochrane. The primary outcome was change in neuropathy symptoms expressed as changes in the Total Symptom Score (TSS) at six months after randomisation. Secondary outcomes were change in neuropathy symptoms at six to 12 months and at 12 to 24 months, change in impairment, change in any validated quality of life total score, complications of DPN, and adverse events. We assessed the certainty of the evidence using GRADE.

MAIN RESULTS

Our analysis incorporated three trials involving 816 participants. Two studies included people with type 1 or type 2 diabetes, while one study included only people with type 2 diabetes. The duration of treatment was between six months and 48 months. We judged all studies at high risk of overall bias due to attrition. ALA compared with placebo probably has little or no effect on neuropathy symptoms measured by TSS (lower score is better) after six months (mean difference (MD) -0.16 points, 95% confidence interval (CI) -0.83 to 0.51; 1 study, 330 participants; moderate-certainty evidence). The CI of this effect estimate did not contain the minimal clinically important difference (MCID) of 0.97 points. ALA compared with placebo may have little or no effect on impairment measured by the Neuropathy Impairment Score-Lower Limbs (NIS-LL; lower score is better) after six months (MD -1.02 points, 95% CI -2.93 to 0.89; 1 study, 245 participants; low-certainty evidence). However, we cannot rule out a significant benefit, because the lower limit of the CI surpassed the MCID of 2 points. There is probably little or no difference between ALA and placebo in terms of adverse events leading to cessation of treatment within six months (risk ratio (RR) 1.48, 95% CI 0.50 to 4.35; 3 studies, 1090 participants; moderate-certainty evidence). No studies reported quality of life or complications associated with DPN.

AUTHORS' CONCLUSIONS

Our analysis suggests that ALA probably has little or no effect on neuropathy symptoms or adverse events at six months, and may have little or no effect on impairment at six months. All the studies were at high risk of attrition bias. Therefore, future RCTs should ensure complete follow-up and transparent reporting of any participants missing from the analyses.

Protein Kinase C (PKC)-mediated TGF-β Regulation in Diabetic Neuropathy: Emphasis on Neuro-inflammation and Allodynia

According to the World Health Organization (WHO), diabetes has been increasing steadily over the past few decades. In developing countries, it is the cause of increased morbidity and mortality. Diabetes and its complications are associated with education, occupation, and income across all levels of socioeconomic status. Factors, such as hyperglycemia, social ignorance, lack of proper health knowledge, and late access to medical care, can worsen diabetic complications. Amongst the complications, neuropathic pain and inflammation are considered the most common causes of morbidity for common populations. This review is focused on exploring protein kinase C (PKC)-mediated TGF-946; regulation in diabetic complications with particular emphasis on allodynia. The role of PKC-triggered TGF-946; in diabetic neuropathy is not well explored. This review will provide a better understanding of the PKC-mediated TGF-946; regulation in diabetic neuropathy with several schematic illustrations. Neuroinflammation and associated hyperalgesia and allodynia during microvascular complications in diabetes are scientifically illustrated in this review. It is hoped that this review will facilitate biomedical scientists to better understand the etiology and target drugs effectively to manage diabetes and diabetic neuropathy.

The effect of Tecar therapy on neurological disorders and nerve conduction velocity of lower limbs in peripheral neuropathy of type 2 diabetic patients: A six-week follow-up study

Objectives

This study aimed to investigate the effect of Tecar therapy on neuropathy symptoms and tibial nerve conduction velocity in individuals with diabetes.

Patients and methods

The single-blind, randomized, sham-controlled clinical trial was conducted between January 2019 and October 2019. Twenty-four type 2 diabetics (8 males, 16 females; mean age: 60.4±8.9 years; range, 40 to 78 years) with peripheral neuropathy were randomly allocated to control (n=12) and study (n=12) groups. The study group received the capacitive Tecar therapy with 10 to 30% intensity and infrared radiation in 10 sessions. The controls received the same protocol with zero intensity. The neuropathy symptoms and nerve conduction velocity were evaluated at baseline, after 10 sessions, and six weeks after the end of sessions.

Results

There were no significant differences in variables (p>0.05). In this way, the homogeneity of the data variables was confirmed. Moreover, the results of two-way mixed analysis of variance showed that improvement of neuropathy symptoms in the study group was significantly more than controls in all stages (p<0.001). After 10 sessions, the results of post hoc analysis showed that the neuropathy symptoms and tibial nerve conduction velocity were significantly improved in both groups (p<0.05). However, there was no change in these outcomes after six weeks in the control group (p>0.05).

Conclusion

Tecar therapy could improve neuropathy symptoms and tibial nerve conduction velocity in diabetic individuals with peripheral neuropathy. Therefore, the use of this method to control the symptoms of diabetic patients can be recommended.

Effects of Neural Mobilization in Diabetic Peripheral Neuropathy: A Scoping Review

Objective

The purpose of this scoping review was to explore the effects of neural mobilization (NM) on outcomes in adults with diabetic peripheral neuropathy (DPN).

Methods

Five databases were searched-PubMed, Web of Science (Web of Science Core Collection), Physiotherapy Evidence Database (PEDro), and Scopus-from inception to January 2022. The studies included were randomized controlled trials, pre-post single group design, multiple case studies, controlled case studies, quasi-experimental studies, and single case studies, which are published in full text in English.

Results

Six studies were included in this review, and most were of low-level evidence. The sample size of the studies ranges from 20 to 43, except for 1 case study, with a total of 158 participants in all the studies combined. In 4 out of 6 studies, only NM was given, whereas in 2 studies, NM was used along with other treatment strategies. The tibial nerve was the most studied nerve, whereas 1 study administered NM to nerves of the upper limbs, and only 1 trial examined the sciatic nerve. The outcomes included the Michigan Neuropathy Screening Instrument questionnaire, nerve conduction velocity, vibration perception threshold, heat/cold perception threshold, weight-bearing asymmetry and range of motion of lower limb, quality of life, and magnetic imaging changes.

Conclusion

At present, only a few low-level studies exist on the use of NM for the treatment of adults with DPN. The evidence for use of NM on DPN is still limited and insufficient.

Heart rate fragmentation is impaired in type 2 diabetes mellitus patients

AIMS

To evaluate the heart rate fragmentation (HRF) of type 2 diabetes mellitus (T2DM) patients and its relationship with heart rate variability (HRV) indices.

METHODS

One hundred sixty-four men, aged 47-57 years were retrospectively analyzed from a database. Participants were T2DM (n = 82) and apparently healthy (n = 82). R-R interval time series recorded by electrocardiogram were collected at the supine position for 10 to 15 min. From HRF, the percentage of inflection points (PIP), percentage of words with zero, one, two, or three inflections points (W₀, W₁, W₂, W₃), and percentage with only type hard, soft, or mixed inflections points type (W^H, W^S, W^M) were quantified.

RESULTS

T2DM presented higher PIP, W^S, W^M and W₃, while W^H and W₁ was lower compared with healthy (p < 0.05). Moreover, a positive moderate correlation was found between W^H and root mean square of the successive R-R differences (RMSSD) and high frequency (HF) indices. In contrast, a negative moderate correlation was found between W^S and W^M with RMSSD and HF indices.

CONCLUSIONS

T2DM have increased fragmentation patterns, and words grouped by inflection type are more closely related to HRV. The HRF approach might be useful to assess heart rate dynamic abnormalities in males with type 2 diabetes.

Inhibiting apoptosis of Schwann cell under the high-glucose condition: A promising approach to treat diabetic peripheral neuropathy using Chinese herbal medicine

Diabetic peripheral neuropathy (DPN) is a common complication of diabetes. Glycemic control and lifestyle alterations cannot prevent the development of DPN; therefore, investigating effective treatments for DPN is crucial. Schwann cells (SCs) maintain the physiological function of peripheral nerves and promote the repair and regeneration of injured nerves. Inhibiting the apoptosis of SCs through various pathological pathways in a high-glucose environment plays an important role in developing DPN. Therefore, inhibiting the apoptosis of SCs can be a novel treatment strategy for DPN. Previous studies have indicated the potential of Chinese herbal medicine (CHM) in treating DPN. In this study, we have reviewed the effects of CHM (both monomers and extracts) on the apoptosis of SCs by interfering with the production of advanced glycation end products, oxidative stress, and endoplasmic reticulum stress pathological pathways. This review will demonstrate the potentialities of CHM in inhibiting apoptosis in SCs, providing new insights and perspectives for treating DPN.

Effectiveness of Photobiomodulation Therapy on Neuropathic Pain, Nerve Conduction and Plantar Pressure Distribution in Diabetic Peripheral Neuropathy - A Systematic Review

BACKGROUND

Diabetic peripheral neuropathy is a severe complication of type 2 diabetes mellitus. The most common symptoms are neuropathic pain and altered sensorium due to damage to small nerve fibers. Altered plantar pressure distribution is also a major risk factor in diabetic peripheral neuropathy, leading to diabetic foot ulcers.

OBJECTIVE

The objective of this systematic review was to analyze the various studies involving photobiomodulation therapy on neuropathic pain and plantar pressure distribution in diabetic peripheral neuropathy.

METHODS

We conducted a systematic review (PubMed, Web of Science, CINAHL, and Cochrane) to summarise the evidence on photobiomodulation therapy for Diabetic Peripheral Neuropathy with type 2 diabetes mellitus. Randomized and non-randomized studies were included in the review.

RESULTS

This systematic review included eight studies in which photobiomodulation therapy showed improvement in neuropathic pain and nerve conduction velocity. It also reduces plantar pressure distribution, which is a high risk for developing foot ulcers.

CONCLUSION

We conclude that photobiomodulation therapy is an effective, non-invasive, and costefficient means to improve neuropathic pain and altered plantar pressure distribution in diabetic peripheral neuropathy.

Oral Nanocurcumin Alone or in Combination with Insulin Alleviates STZ-Induced Diabetic Neuropathy in Rats

Diabetes mellitus (DM), a multifaceted metabolic disorder if not managed properly leads to secondary complications. Diabetic peripheral neuropathy (DPN) is one such complication caused by nerve damage that cannot be reversed but can be delayed. Recently, diabetes patients are using dietary supplements, although there remains a general skepticism about this practice. Curcumin (CUR), one such supplement can help prevent underlying low-grade inflammation in diabetes, but it is plagued by poor oral bioavailability. To better understand the role of bioavailability in clinical outcomes, we have tested double-headed nanosystems containing curcumin (nCUR) on DPN. Because CUR does not influence glucose levels, we have also tested the effects of nCUR combined with long-acting subcutaneous insulin (INS). nCUR with or without INS alleviates DPN at two times lower dose than unformulated CUR, as indicated by qualitative and quantitative analysis of the hind paw, sciatic nerve, spleen, and L4-6 spinal cord. In addition, nCUR and nCUR+INS preserve hind paw nerve axons as evident by the Bielschowsky silver stain and intraepidermal nerve fibers (IENF) density measured by immunofluorescence. The mechanistic studies further corroborated the results, where nCUR or nCUR+INS showed a significant decrease in TUNEL positive cells, mRNA expression of NLRP3, IL-1β, and macrophage infiltration while preserving nestin and NF200 expression in the sciatic nerve. Together, the data confirms that CUR bioavailability is proportional to clinical outcomes and INS alone may not be one of the solutions for DM. This study highlights the potential of nCUR with or without INS in alleviating DPN and warrants further investigation.

Efficacy of vitamin and antioxidant supplements for treatment of diabetic peripheral neuropathy: systematic review and meta-analysis of randomized controlled trials

ABSTRACTThe results of treatment effect of vitamin or antioxidant intake on diabetic peripheral neuropathy (DPN) was inconsistent. Therefore, we performed a meta-analysis of randomized controlled trials (RCTs) to examine whether these supplements are effective in DPN treatment. We searched seven databases from inception to October 2021. All RCTs of DPN treatments with vitamin and antioxidant supplements were included. We performed sensitivity and subgroup analysis, and also tested for publication bias by the funnel plot and Egger's test. A total of 14 studies with 1384 patients were included in this systematic review. Three high-quality trials showed that vitamin and antioxidant supplements significantly increased sensory nerve conduction velocity (SNCV) of the sural nerve (MD = 2.66, 95%CI (0.60, 4.72), P < 0.05, I²= 0%). Seven studies (758 participants) suggested that these supplements might have improvement on motor nerve conduction velocity (MNCV) of the peroneal nerve in DPN patients with the random-effect model (MD = 0.60, 95%CI (0.28, 0.92), P < 0.05, I²= 65%). In four studies, these supplements could have improved on MNCV of the median nerve with the fixed-effect model (MD = 4.22, 95%CI (2.86, 5.57), P < 0.05, I²= 0%). However, ten studies (841 participants) have suggested that vitamin and antioxidant supplements have not decreased glycosylated haemoglobin (HbA1c). Vitamin and antioxidant supplements may improve the conduction velocity of nerves, including median, sural and peroneal nerves of patients with DPN. But these supplements have not decreased HbA1c in DPN patients. Several trials with a large sample size are needed to provide evidence support for clinical practice in the future.

Cardiovascular risk factor management in patients with diabetes: Does management differ with disease duration?

AIMS

Our objective was to examine risk factor modification targets and treatment in relation to duration of diabetes.

METHODS

The Diabetes Mellitus Status in Canada (DM-SCAN) study collected data on 5109 patients with type 2 diabetes mellitus (T2DM) in 2012 in primary care. We compared the prevalence of vascular complications, treatment targets, and interventions between patients with diagnosed diabetes duration ≤10 and > 10 years.

RESULTS

Physicians more frequently assigned HbA1c (glycated hemoglobin) targets of 7.1-8.5% (54-69 mmol/mol) to patients with longer duration of diabetes (n = 1647) (19.8% vs 9.5%, p < 0.001). Patients with longer duration of diabetes were less likely to achieve HbA1c targets of ≤7.0% (53 mmol/mol) (39% vs. 55%, p < 0.001), had similar likelihood of achieving blood pressure targets of ≤130/80 mmHg (38% vs. 36%, p = 0.26) and were more likely to achieve LDL-C targets of ≤2.0 mmol/L (≤77.3 mg/dL) (63% vs. 53%, p < 0.001) compared to patients with shorter duration of diabetes (n = 3462). Achievement of all three targets between both groups were similar (13% vs. 13%, p = 0.82). Overall, patients with longer duration of diabetes were more likely to be prescribed anti-hyperglycemic, anti-hypertensive, lipid-lowering medications and referred for diabetes education.

CONCLUSIONS

Only 13% of patients achieved glycemic, blood pressure, and LDL-C targets irrespective of duration of diabetes. Despite being managed with more medications, patients with longer duration of diabetes were less likely to achieve glycemic targets. More focus is needed on developing methods to bridge best care and real-world practice.

Ankle Proprioception in Patients with Type 2 Diabetes Mellitus

BACKGROUND

Ankle position sense may be reduced before the appearance of the clinical manifestation of diabetic peripheral neuropathy. This is known to impair gait and cause falls and foot ulcers. Early detection of impaired ankle proprioception is important because it allows physicians to prescribe an exercise program to patients to prevent foot complications.

METHODS

Forty-six patients diagnosed as having type 2 diabetes mellitus and 22 control patients were included in the study. Presence of neuropathy was assessed using the Michigan Neuropathy Screening Instrument (MNSI). Level of foot care awareness was determined using the Nottingham Assessment of Functional Footcare (NAFF). Joint position sense was measured using a dynamometer.

RESULTS

Mean absolute angular error (MAAE) values were significantly higher in the neuropathy group compared with the control group (P < .05). Right plantarflexion MAAE values were significantly lower in the group without neuropathy compared with the group with neuropathy (P < .05). No correlation was found between MAAE values (indicating joint position sense) and age, educational level, disease duration, glycemic control, NAFF score, and MNSI history and examination scores in the groups with and without neuropathy (P > .05). Educational level and disease duration were found to be correlated with NAFF scores.

CONCLUSIONS

Increased MNSI history scores and increased deficits in ankle proprioception demonstrate that diabetic foot complications associated with reduced joint position sense may be seen at an increased rate in symptomatic patients.

Performance Analysis of Conventional Machine Learning Algorithms for Diabetic Sensorimotor Polyneuropathy Severity Classification

Background: Diabetic peripheral neuropathy (DSPN), a major form of diabetic neuropathy, is a complication that arises in long-term diabetic patients. Even though the application of machine learning (ML) in disease diagnosis is a very common and well-established field of research, its application in diabetic peripheral neuropathy (DSPN) diagnosis using composite scoring techniques like Michigan Neuropathy Screening Instrumentation (MNSI), is very limited in the existing literature. Method: In this study, the MNSI data were collected from the Epidemiology of Diabetes Interventions and Complications (EDIC) clinical trials. Two different datasets with different MNSI variable combinations based on the results from the eXtreme Gradient Boosting feature ranking technique were used to analyze the performance of eight different conventional ML algorithms. Results: The random forest (RF) classifier outperformed other ML models for both datasets. However, all ML models showed almost perfect reliability based on Kappa statistics and a high correlation between the predicted output and actual class of the EDIC patients when all six MNSI variables were considered as inputs. Conclusions: This study suggests that the RF algorithm-based classifier using all MNSI variables can help to predict the DSPN severity which will help to enhance the medical facilities for diabetic patients.

A new mechanistic approach for the treatment of chronic neuropathic pain with nitrous oxide integrated from a systems biology narrative review

The limitations of the currently available treatments for chronic neuropathic pain highlight the need for safer and more effective alternatives. The authors carried out a focused review using a systems biology approach to integrate the complex mechanisms of nociception and neuropathic pain, and to decipher the effects of nitrous oxide (N₂O) on those pathways, beyond the known effect of N₂O on N-methyl-D-aspartate receptors. This review identified a number of potential mechanisms by which N₂O could impact the processes involved in peripheral and central sensitization. In the ascending pathway, the effects of N₂O include activating TWIK-related K⁺ channel 1 potassium channels on first-order neurons, blocking voltage-dependent calcium channels to attenuate neuronal excitability, attenuating postsynaptic glutamatergic receptor activation, and possibly blocking voltage-dependent sodium channels. In the descending pathway, N₂O induces the release of endogenous opioid ligands and stimulates norepinephrine release. In addition, N₂O may mediate epigenetic changes by inhibiting methionine synthase, a key enzyme involved in DNA and RNA methylation. This could explain why this short-acting analgesic has shown long-lasting anti-pain sensitization effects in animal models of chronic pain. These new hypotheses support the rationale for investigating N₂O, either alone or in combination with other analgesics, for the management of chronic neuropathic pain.

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

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSION

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

Blood-Nerve Barrier (BNB) Pathology in Diabetic Peripheral Neuropathy and In Vitro Human BNB Model

In diabetic peripheral neuropathy (DPN), metabolic disorder by hyperglycemia progresses in peripheral nerves. In addition to the direct damage to peripheral neural axons, the homeostatic mechanism of peripheral nerves is disrupted by dysfunction of the blood–nerve barrier (BNB) and Schwann cells. The disruption of the BNB, which is a crucial factor in DPN development and exacerbation, causes axonal degeneration via various pathways. Although many reports revealed that hyperglycemia and other important factors, such as dyslipidemia-induced dysfunction of Schwann cells, contributed to DPN, the molecular mechanisms underlying BNB disruption have not been sufficiently elucidated, mainly because of the lack of in vitro studies owing to difficulties in establishing human cell lines from vascular endothelial cells and pericytes that form the BNB. We have developed, for the first time, temperature-sensitive immortalized cell lines of vascular endothelial cells and pericytes originating from the BNB of human sciatic nerves, and we have elucidated the disruption to the BNB mainly in response to advanced glycation end products in DPN. Recently, we succeeded in developing an in vitro BNB model to reflect the anatomical characteristics of the BNB using cell sheet engineering, and we established immortalized cell lines originating from the human BNB. In this article, we review the pathologic evidence of the pathology of DPN in terms of BNB disruption, and we introduce the current in vitro BNB models.

Non-glucose risk factors in the pathogenesis of diabetic peripheral neuropathy

In this review, we consider the diverse risk factors in diabetes patients beyond hyperglycemia that are being recognized as contributors to diabetic peripheral neuropathy (DPN). Interest in such alternative mechanisms has been encouraged by the recognition that neuropathy occurs in subjects with metabolic syndrome and pre-diabetes and by the reporting of several large clinical studies that failed to show reduced prevalence of neuropathy after intensive glucose control in patients with type 2 diabetes. Animal models of obesity, dyslipidemia, hypertension, and other disorders common to both pre-diabetes and diabetes have been used to highlight a number of plausible pathogenic mechanisms that may either damage the nerve independent of hyperglycemia or augment the toxic potential of hyperglycemia. While pathogenic mechanisms stemming from hyperglycemia are likely to be significant contributors to DPN, future therapeutic strategies will require a more nuanced approach that considers a range of concurrent insults derived from the complex pathophysiology of diabetes beyond direct hyperglycemia.

Correlates of diabetic polyneuropathy of the elderly in Sub-Saharan Africa

Background

Diabetic polyneuropathy is associated with significant physical disability among older adults. However, their frequency and correlates are not well known in the older adults in Sub-Saharan-Africa. The objectives were to evaluate the hospital-based prevalence of diabetic polyneuropathy and identify its correlates in older adults.

Methods

Over a period of 5 months, a cross-sectional survey was carried out at Douala Laquintinie Hospital (DLH), a main reference hospital in Douala, the economic capital of Cameroon. Participants in our study group comprised all patients with type 2 diabetes, whatever the reason for their reporting to the hospital. Diabetic Polyneuropathy was defined according to a Diabetic Neuropathy Examination score > 3/16.

Results

A total of 159 older adults with diabetes were examined during this recruitment period, among whom 106 (66.7%) were women. The mean age was 68.3 ± 6.5 years. Diabetes median duration was 108 months. For all patients assessed using the Diabetic Neuropathy Examination score, polyneuropathy was reported in 31.4%; among them, polyneuropathy proved symptomatic in 78% of them. Correlates of polyneuropathy were glycated hemoglobin (p = 0.049), HIV infection (p = 0.031) and albuminuria (p< 0.001), even after adjustment for age, gender and duration of diabetes.

Conclusion

A third of older adults with diabetes who visited our hospital were diagnosed with prevalent diabetes-related polyneuropathy. It shows that early detection is required through routine screening and regular follow-up examinations in order to reduce the risk of disability and improve the quality of life in elderly diabetics.

Interfascicular Gliding Dysfunction Relation with Focal Neuropathy in Diabetic Patients with Carpal Tunnel Syndrome

Carpal tunnel syndrome (CTS), a common neuropathy of the upper limb, is highly prevalent in diabetic patients. Recent findings indicate that changes in median nerve elasticity and its gliding characteristics may contribute to the development of CTS. Normally, each nerve should be able to adapt to the positional changes by passive movement relative to the surrounding tissues. This ability is provided by a gliding apparatus around the nerve trunk in the surrounding soft tissue. The fascicles of nerve trunks can also glide against each other (interfascicular gliding). Sonoelastography indicates that nerve elasticity is decreased in patients with CTS compared to healthy patients. Moreover, decreased nerve elasticity in diabetes mellitus type II is associated with increased neuropathy, especially in peripheral nerves. Biomechanical factors, oxidative stress, and microvascular defects are also observed in diabetic neuropathy and account for different complications. A reduction in the elasticity of peripheral nerves may be related to decreased interfascicular gliding because of the biomechanical changes that occur in neuropathy. Surgical treatments, including nerve release and reduction of carpal tunnel pressure, improve peripheral gliding but do not resolve disease symptoms completely. According to the evidence, interfascicular gliding dysfunction is the most important factor in the pathogenesis of CTS in diabetic patients. Available evidence suggests that biomechanical variations affect interfascicular gliding more than peripheral gliding in diabetic patients. Decreased nerve elasticity is strongly correlated with decreased interfascicular gliding. It is further hypothesized that the concurrent use of antioxidants and pharmacological treatment (neuroprotection) such as alpha lipoic acid with carpal tunnel release in diabetic patients may alleviate the interfascicular gliding dysfunction and improve median neve elasticity. Decreased nerve elasticity and interfascicular gliding dysfunction play significant roles in the pathogenesis of CTS in diabetic patients.

Understanding Diabetic Neuropathy: Focus on Oxidative Stress

Diabetic neuropathy is one of the clinical syndromes characterized by pain and substantial morbidity primarily due to a lesion of the somatosensory nervous system. The burden of diabetic neuropathy is related not only to the complexity of diabetes but also to the poor outcomes and difficult treatment options. There is no specific treatment for diabetic neuropathy other than glycemic control and diligent foot care. Although various metabolic pathways are impaired in diabetic neuropathy, enhanced cellular oxidative stress is proposed as a common initiator. A mechanism-based treatment of diabetic neuropathy is challenging; a better understanding of the pathophysiology of diabetic neuropathy will help to develop strategies for the new and correct diagnostic procedures and personalized interventions. Thus, we review the current knowledge of the pathophysiology in diabetic neuropathy. We focus on discussing how the defects in metabolic and vascular pathways converge to enhance oxidative stress and how they produce the onset and progression of nerve injury present in diabetic neuropathy. We discuss if the mechanisms underlying neuropathy are similarly operated in type I and type II diabetes and the progression of antioxidants in treating diabetic neuropathy.

Beneficial effects of fish oil enriched in omega-3 fatty acids on the development and maintenance of neuropathic pain

OBJECTIVE

The aim of this work was to assess the preventive effect of an eicosapentaenoic acid/docosahexaenoic acid-concentrate fish oil on neuropathic pain development and regenerative features of sciatic nerve in rats.

METHODS

In the present study, rats with chronic constriction injury (CCI) of the sciatic nerve and sham-operated ones received fish oil enriched in omega-3 fatty acids (0.36 or 0.72 g/kg per day, oral) or saline solution for 21 days, with thermal hyperalgesia and mechanical allodynia being assessed before and 3, 7, 14 and 21 days after injury.

KEY FINDINGS

Fish oil enriched in omega-3 fatty acids (0.72 g/kg) reversed thermal hyperalgesia and significantly reduced mechanical allodynia. In addition, ω-3 treatment (0.72 g/kg) promoted the recovery of the Sciatic Functional Index as well as restored axonal density and morphology, without the formation of neuroma in the injured sciatic nerves after 21 days.

CONCLUSION

We conclude that the fish oil enriched in omega-3 fatty acids administration relieves thermal hyperalgesia and mechanical allodynia effectively and also enhances the recovery process in rats with CCI of the sciatic nerve. These findings might contribute to new therapeutic approaches including omega-3 fatty acids in neuropathic pain treatment.

Development of grading scales of pedal sensory loss using Mokken scale analysis on the Rotterdam Diabetic Foot Study Test Battery data

INTRODUCTION

Loss of sensation due to diabetes-related neuropathy often leads to diabetic foot ulceration. Several test instruments are used to assess sensation, such as static and moving 2-point discrimination (S2PD, M2PD), monofilaments, and tuning forks.

METHODS

Mokken scale analysis was applied to the Rotterdam Diabetic Foot Study data to select hierarchies of tests to construct measurement scales.

RESULTS

We developed 39-item and 31-item scales to measure loss of sensation for research purposes and a 13-item scale for clinical practice. All instruments were strongly scalable and reliable. The 39 items can be classified into 5 hierarchically ordered core clusters: S2PD, M2PD, vibration sense, monofilaments, and prior ulcer or amputation.

DISCUSSION

Guided by the presented scales, clinicians may better classify the grade of sensory loss in diabetic patients' feet. Thus, a more personalized approach concerning individual recommendations, intervention strategies, and patient information may be applied.

Inhibition of miR-25 aggravates diabetic peripheral neuropathy

The hyperglycemia-induced enhanced oxidative stress is a key factor of diabetic peripheral neuropathy implicated in the pathogenesis of diabetic neuropathy, and microRNA may be involved, playing promotion or protection roles. In this study, we aimed to investigate the function of miR-25 during the development of oxidative/nitrative stress and in subsequent neurological problems. We detected the oxidative stress effects and expression of miR-25 on sciatic nerves from db/db diabetic model mice and analyzed the expression of related genes by qPCR and Western blotting. Interestingly, we observed increased reactive oxygen species (ROS) and Nox4 expression in db/db mice accompanied with reduced miR-25. MiR-25 inhibitor treatment increased nicotinamide adenine dinucleotide phosphate activity in Schwann cells, whereas miR-25 precursor overexpression led to opposite results. MiR-25 precursor reduced the activation of protein kinase C and decreased Nox4 expression at both mRNA and protein levels. Advanced glycation endproducts (AGEs) and the receptor for advanced glycation endproducts (RAGE) were increased in the serum and in the peripheral nerves obtained from diabetic mice, and miR-25 inhibitor treatment in Schwann cells from wt mice led to the same effect. However, miR-25 precursor transfection reduced AGEs and RAGE, and further reduced inflammatory factors that contribute to the pathological process of peripheral nerves. These findings, for the first time, indicate that miR-25 acts as a protection factor in diabetic neuropathy by downregulating AGE-RAGE and reducing nicotinamide adenine dinucleotide phosphate oxidase. miR-25 reduced protein kinase C-α phosphorylation to produce less reactive oxygen species in diabetic peripheral nerves, and therefore it played an important role in the regulation of oxidative/nitrative stress and in consequent neurological dysfunction.

Altered pain processing in people with type I and II diabetes: a protocol for a systematic review and meta-analysis of pain threshold and pain modulation mechanisms

BACKGROUND

Peripheral neuropathies are a common complication in patients with diabetes. Changes in nerve function and central pain processing can be quantified by assessing pain thresholds and pain modulation mechanisms.

AIM

To summarise the literature which compares pain thresholds and pain modulation mechanisms in people with diabetes without neuropathies, with non-painful diabetic neuropathies and with painful diabetic neuropathies, and in people without diabetes.

METHODS

A systematic review and meta-analysis will be conducted. Terms related to diabetes, pain thresholds and pain modulation mechanisms will be combined in a structured search in MEDLINE, CINAHL, EMBASE, the Cochrane Library, SPORTDiscus, Web of Science and PEDro. Publications on adults (18 years and older) with diabetes and at least one pain threshold measure following thermal, mechanical or electrical stimuli and/or at least one pain modulation mechanisms (temporal summation or conditioned pain modulation) with a comparison group will be considered. There will be no restriction regarding language or year of publication. One investigator will screen records based on title and abstract (ESS). Two independent investigators (ESS and MC) will select full-text papers and assess risk of bias using a modified Downs and Black checklist. Potential disagreements will be resolved with a third investigator (LB). One investigator (ESS) will extract all data and a second investigator (MS) will extract data for 20% of the papers to verify accuracy of the process. A sensitivity analysis for publication bias will be conducted.

DISCUSSION

This systematic review and meta-analysis will summarise the evidence on pain threshold profiles and pain modulation mechanisms in people with diabetes without and with neuropathies (both painful and non-painful). This will provide more insight in the clinical presentation and progression of diabetic neuropathies.

SYSTEMATIC REVIEW REGISTRATION

PROSPERO CRD42018088173.

[Alpha-lipoic acid in the treatment of diabetic polyneuropathy]

The issues of classification, pathogenesis, pathomorphology and treatment of diabetic polyneuropathy (DPN) are addressed. Pathogenetic mechanisms of the action of alpha-lipoic acid in treatment of DPN are justified. The authors present the results of randomized placebo-controlled trials of alpha-lipoic acid that revealed the high clinical efficacy and absence of side-effects even during the long-term treatment.

Diabetic Microvascular Disease: An Endocrine Society Scientific Statement

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

Clinical characteristics and risk factors of diabetic peripheral neuropathy of type 1 diabetes mellitus patients

BACKGROUND

Small nerve fibers are more easily injured than large ones for diabetic peripheral neuropathy (DPN). The study investigated the characteristics and related risk factors of DPN of T1DM patients using nerve conduction velocity and CPT values, which provided evidences for its early diagnosis.

METHODS

70 T1DM patients and 48 healthy volunteers were included. All subjects accepted nerve conduction velocity and CPT examinations for four limbs. Detailed clinical indicators were recorded. CPT values were compared between TIDM group and control group. The risk factors affecting DPN were further explored.

RESULTS

Compared with the control group, CPT values under three frequencies were decreased in T1DM group. The abnormality rate of sural nerves was higher than that of median nerves (P<0.001). Median nerve dysfunction mainly presented as hypoesthesia under 250Hz and 5Hz current stimulus. And sural nerve dysfunction mainly presented as hyperesthesia under three frequencies. Compared with left median nerve, abnormal rate of right median nerve was higher under 2000Hz current stimulus (P=0.035). However, abnormal rate of left sural nerve was higher than that of right side under 250Hz and 5Hz current stimulus (P=0.001, <0.001). Duration, NDS scores and CPT values of right median nerve under 2000Hz current stimulus were independent risk factors of abnormal nerve conduction velocity.

CONCLUSIONS

The study proved that DPN of T1DM are mainly lower limb-injured., amyelinated and thin myelinated nerve fiber-involved. CPT can be combined with traditional nerve conduction velocity examination, which will help the diagnosis of DPN of T1DM earlier and more comprehensively.

Association of Diabetes Related Complications with Heart Rate Variability among a Diabetic Population in the UAE

Microvascular, macrovascular and neurological complications are the key causes of morbidity and mortality among type II diabetes mellitus (T2DM) patients. The aim of this study was to investigate the alterations of cardiac autonomic function of diabetic patients in relation to three types of diabetes-related complications. ECG recordings were collected and analyzed from 169 T2DM patients in supine position who were diagnosed with nephropathy (n = 55), peripheral neuropathy (n = 64) and retinopathy (n = 106) at two hospitals in the UAE. Comparison between combinations of patients with complications and a control diabetic group (CONT) with no complication (n = 34) was performed using time, frequency and multi-lag entropy measures of heart rate variability (HRV). The results show that these measures decreased significantly (p<0.05) depending on the presence and type of diabetic complications. Entropy, (median, 1st- 3rd interquartile range) for the group combining all complications (1.74,1.37-2.09) was significantly lower than the corresponding values for the CONT group (1.77, 1.39-2.24) with lag-1 for sequential beat-to-beat changes. Odds ratios (OR) from the entropy analysis further demonstrated a significantly higher association with the combination of retinopathy and peripheral neuropathy versus CONT (OR: 1.42 at lag 8) and an even OR for the combination of retinopathy and nephropathy (OR: 2.46 at lag 8) compared to the other groups with complications. Also, the OR of low frequency power to high frequency power ratio (LF/HF) showed a higher association with these diabetic-related complications compared to CONT, especially for the patient group combining all complications (OR: 4.92). This study confirms that the type of microvascular or peripheral neuropathy complication present in T2DM patients have different effects on heart rate entropy, implying disorders of multi-organ connectivity are directly associated with autonomic nervous system dysfunction. Clinical practice may benefit from including multi-lag entropy for cardiac rhythm analysis in conjunction with traditional screening methods in patients with diabetic complications to ensure better preventive and treatment outcomes in the Emirati Arab population.

[Clinical features and diagnosis of diabetic polyneuropathy]

Diabetic polyneuropathy (DPN) is a serious complication of diabetes that leads to early disability in patients if late diagnosed. There has been a lot of research into pathophysiological mechanisms of nerve fiber damage and risk factors for neurological complications of diabetes. Early diagnosis of the latter is quite a challenge and, thus, the problem of finding more reliable diagnostic modalities is rather pressing. In this review, an interdisciplinary approach to the said problem, high-end diagnostic methods, and clinical features of DPN are described.

Association of sudomotor function with peripheral artery disease in type 2 diabetes

Peripheral artery disease (PAD) is the major risk factor for cardiovascular disease and lower extremity amputation in patients with diabetes. Autonomic neuropathy is a risk factor for cardiovascular-related morbidity and mortality. Sudomotor dysfunction is well established in type 2 diabetes mellitus (T2DM) and reflects small fibre neuropathy, cardiovascular autonomic neuropathy and peripheral sympathetic autonomic neuropathy. However, the relationship between sudomotor dysfunction and PAD remains unexplored. Therefore, the aim of present study was to explore the association of sudomotor function with ankle-brachial index (ABI) and C-reactive protein (CRP) in T2DM. In this cross-sectional study, we recruited 36 consecutive type 2 diabetes patients and 20 age- and sex-matched healthy controls. Sudomotor function was assessed using Sudoscan (Sudoscan-Impeto Medical Device, EZS 01750010193, Paris, France), which detects sweat gland function through measurement of electrochemical skin conductance of both hands and feet. Measurement of ankle-brachial ABI was carried out with sphygmomanometer and Doppler device (Hadeco Bidop ES-100V3). Glycated haemoglobin (HbA1c), fasting plasma glucose, and inflammatory marker CRP were also measured. Type 2 diabetic patients had significantly impaired sudomotor function (48.14 ± 8.28 vs. 76.48 ± 6.72 µs), lower ABI (0.89 ± 0.25 vs. 1.15 ± 0.11) and elevated CRP (5.32 ± 2.41 vs. 2.45 ± 1.11 mg/l) as compared to healthy controls, respectively (p < 0.01). Sudoscan scores were found to be inversely correlated with CRP and HbA1c, and directly correlated with ABI (p < 0.05) in the patients. Sudomotor dysfunction is associated with significant peripheral artery disease, vascular inflammation and impaired glycaemic status.

Is Stem Cell Transplantation Ready for Prime Time in Diabetic Polyneuropathy?

Diabetic polyneuropathy (DPN) is the most common complication that emerges early in patients who have diabetes. Curative treatment for overt or symptomatic DPN has not been established, requiring much effort to explore new modalities. Thus, the use of various kinds of stem cells as a potential therapeutic option for DPN is of particular interest. The beneficial effects were proposed to be attributed to either cytokine released from transplanted stem cells or the differentiation of stem cells to substitute the damaged peripheral nerve. Furthermore, based on the concept that humoral factors secreted from stem cells play a pivotal role in tissue regeneration, the utilization of conditioned medium derived from the stem cell culture serves as a novel tool for regenerative therapy. However, many questions have not been yet answered to determine whether stem cell therapy is essential in clinical application of DPN. In this report, we review the current status of preclinical studies on stem cell therapy for DPN and discuss future prospects.

Recent Advances in Diagnostic Strategies for Diabetic Peripheral Neuropathy

Diabetes is an increasing epidemic in Korea, and associated diabetic peripheral neuropathy (DPN) is its most common and disabling complication. DPN has an insidious onset and heterogeneous clinical manifestations, making it difficult to detect high-risk patients of DPN. Early diagnosis is recommended and is the key factor for a better prognosis and preventing diabetic foot ulcers, amputation, or disability. However, diagnostic tests for DPN are not clearly established because of the various pathophysiology developing from the nerve injury to clinical manifestations, differences in mechanisms according to the type of diabetes, comorbidities, and the unclear natural history of DPN. Therefore, DPN remains a challenge for physicians to screen, diagnose, follow up, and evaluate for treatment response. In this review, diagnosing DPN using various methods to assess clinical symptoms and/or signs, sensorineural impairment, and nerve conduction studies will be discussed. Clinicians should rely on established modalities and utilize current available testing as complementary to specific clinical situations.

Correlation of Michigan neuropathy screening instrument, United Kingdom screening test and electrodiagnosis for early detection of diabetic peripheral neuropathy

Background

Almost half of Diabetic Peripheral Neuropathies (DPNs) are symptom-free. Methods including questionnaires and electrodiagnosis (EDx) can be fruitful for easy reach to early diagnosis, correct treatments of diabetic neuropathy, and so decline of complications for instance diabetic foot ulcer and prevention of high costs. The goal of our study was to compare effectiveness of the Michigan neuropathy screening instrument (MNSI), United Kingdom screening test (UKST) and electrophysiological evaluation in confirming diabetic peripheral neuropathy.

Methods

One hundred twenty five known diabetes mellitus male and female subjects older than 18 with or without symptoms of neuropathy comprised in this research. All of them were interviewed in terms of demographic data, lipid profile, HbA1C, duration of disease, and history of retinopathy, so examined by Michigan neuropathy screening instrument (MNSI), United Kingdom screening test (UKST), and nerve conduction studies (NCS). The collected data were analyzed by SPSS software 18.

Results

One hundred twenty five diabetic patients (70 female, 55 male) were recruited in this study with a mean age of 58.7 ± 10.2, and mean duration of diabetes was 10.17 ± 6.9 years. The mean neuropathy score of MNSI and UKST were 2.3 (1.7) and 4.16 (2.9), respectively. Each instrument detected the peripheral neuropathy in 78 (69 %) and 91 (73 %) of patients, respectively. There was a significant relationship between number of neuropathies and mean of diabetes duration and development of retinopathy in both questionnaire evaluations and NCS. By nerve conduction study, neuropathy was detected in 121 (97 %) diabetic patients were reported in order 15 (12 %) mononeuropathy (as 33 % sensory and 67 % motor neuropathy) and 106 (85 %) polyneuropathy (as 31 % motor and 69 % sensorimotor neuropathy).

Conclusions

As regards NCS is an objective, simple, and non-invasive tool and also can determine level of damage and regeneration in peripheral nerves, this study suggests electrodiagnosis as a convenient option for screening, confirming, and follow up of diabetic peripheral neuropathy.

Adenosine Monophosphate-Activated Protein Kinase Abates Hyperglycaemia-Induced Neuronal Injury in Experimental Models of Diabetic Neuropathy: Effects on Mitochondrial Biogenesis, Autophagy and Neuroinflammation

Impaired adenosine monophosphate kinase (AMPK) signalling under hyperglycaemic conditions is known to cause mitochondrial dysfunction in diabetic sensory neurons. Facilitation of AMPK signalling is previously reported to ameliorate inflammation and induce autophagic response in various complications related to diabetes. The present study assesses the role of AMPK activation on mitochondrial biogenesis, autophagy and neuroinflammation in experimental diabetic neuropathy (DN) using an AMPK activator (A769662). A769662 (15 and 30 mg/kg, i.p) was administered to Sprague-Dawley rats (250-270 g) for 2 weeks after 6 weeks of streptozotocin (STZ) injection (55 mg/kg, i.p.). Behavioural parameters (mechanical/thermal hyperalgesia) and functional characteristics (motor/sensory nerve conduction velocities (MNCV and SNCV) and sciatic nerve blood flow (NBF)) were assessed. For in vitro studies, Neuro2a (N2A) cells were incubated with 25 mM glucose to simulate high glucose condition and then studied for mitochondrial dysfunction and protein expression changes. STZ administration resulted in significant hyperglycaemia (>250 mg/dl) in rats. A769662 treatment significantly improved mechanical/thermal hyperalgesia threshold and enhanced MNCV, SNCV and NBF in diabetic animals. A769662 exposure normalised the mitochondrial superoxide production, membrane depolarisation and markedly increased neurite outgrowth of N2A cells. Further, AMPK activation also abolished the NF-κB-mediated neuroinflammation. A769662 treatment increased Thr-172 phosphorylation of AMPK results in stimulated PGC-1α-directed mitochondrial biogenesis and autophagy induction. Our study supports that compromised AMPK signalling in hyperglycaemic conditions causes defective mitochondrial biogenesis ultimately leading to neuronal dysfunction and associated deficits in DN and activation of AMPK can be developed as an attractive therapeutic strategy for the management of DN.

Effects of Ezetimibe/Simvastatin and Rosuvastatin on Oxidative Stress in Diabetic Neuropathy: A Randomized, Double-Blind, Placebo-Controlled Clinical Trial

Objective. To evaluate the effects of ezetimibe/simvastatin (EZE/SIMV) and rosuvastatin (ROSUV) on oxidative stress (OS) markers in patients with diabetic polyneuropathy (DPN). Methods. We performed a randomized, double-blind, placebo-controlled phase III clinical trial in adult patients with Type 2 Diabetes Mellitus (T2DM) and DPN, as evaluated by composite scores and nerve conduction studies (NCS). Seventy-four subjects with T2DM were allocated 1 : 1 : 1 to placebo, EZE/SIMV 10/20 mg, or ROSUV 20 mg for 16 weeks. All patients were assessed before and after treatment: primary outcomes were lipid peroxidation (LPO), and nitric oxide (NO) surrogate levels in plasma; secondary outcomes included NCS, neuropathic symptom scores, and metabolic parameters. Data were expressed as mean ± SD or SEM, frequencies, and percentages; we used nonparametric analysis. Results. LPO levels were reduced in both statin arms after 16 weeks of treatment (p < 0.05 versus baseline), without changes in the placebo group. NO levels were not significantly affected by statin treatment, although a trend towards significance concerning increased NO levels was noted in both statin arms. No significant changes were observed for the NCS or composite scores. Discussion. EZE/SIMV and ROSUV are superior to placebo in reducing LPO in subjects with T2DM suffering from polyneuropathy. This trial is registered with NCT02129231.

Association study of C936T polymorphism of the VEGF gene and the C242T polymorphism of the p22phox gene with diabetes mellitus type 2 and distal diabetic polyneuropathy

Even with long‑term glycemic control, diabetes mellitus type 2 (DM2) remains the predominant cause of diabetic neuropathy. Single nucleotide polymorphism (SNP) C936T of the vascular endothelial growth factor (VEGF) gene and the SNP C242T of the p22phox (CYBA) gene have been investigated in relation to DM2 and its complications. The aim of the present study was to investigate the association between these two SNPs and DM2, and also between the SNPs and the signs and symptoms of diabetic distal polyneuropathy. The DM2 group consisted of 98 individuals and the control group consisted of 104 individuals. The results demonstrated that there was no association between the different genotypes or alleles and increased risk of the disease (P>0.05). With SNP C242T, a significant association with body mass index between the CTxTT genotypes (P=0.043) was identified; and the greatest body mass indexes were among individuals with the TT genotype. An association between the degree of neuropathic symptoms and genotypic/allelic distribution of these polymorphisms was not observed. In conclusion, the investigated polymorphisms are not correlated with the risk of developing DM2.

Molecular network-based analysis of guizhi-shaoyao-zhimu decoction, a TCM herbal formula, for treatment of diabetic peripheral neuropathy

AIM

Guizhi-shaoyao-zhimu decoction (GSZ), a traditional Chinese medicine (TCM) herbal formula, has been shown effective in the treatment of diabetic peripheral neuropathy (DPN). In this study, network analysis was performed to decipher the molecular mechanisms of GSZ in the treatment of DPN.

METHODS

The chemical components of the 3 herbs forming GSZ, ie, Ramulus Cinnamomi (Guizhi), Paeonia lactiflora (Shaoyao) and Rhizoma Anemarrhenae (Zhimu), were searched in Chinese medicine dictionaries, and their target proteins were identified in PubChem. DPN genes were searched in PubMed gene databases. Ingenuity Pathway Analysis (IPA) was used to build the GSZ pharmacological network and DPN molecular network. The canonical pathways between the two networks were compared to decipher the molecular mechanisms of GSZ in the treatment of DPN.

RESULTS

Sixty-one protein targets for Guizhi, 31 targets for Shaoyao, 47 targets for Zhimu, as well as 23 genes related to DPN were identified and uploaded to IPA. The primary functions of the DPN molecular network were inflammatory response, metabolic disease, cellular assembly and organization. As far as the pharmacological network functions were concerned, Guizhi target proteins were involved in neurological disease, inflammatory disease, cellular growth and proliferation, cell signaling, molecular transport, and nucleic acid metabolism, Shaoyao target proteins were related to neurological disease, inflammatory disease, and Zhimu target proteins focused on cell death and survival, cellular movement, immune cell trafficking, DNA replication, recombination and repair, and cell cycle. In the three-herb combination GSZ, several new network functions were revealed, including the inflammatory response, gene expression, connective tissue development and function, endocrine system disorders, and metabolic disease. The canonical pathway comparison showed that Shaoyao focused on IL-12 signaling and production in macrophages, and Zhimu focused on TNFR2 signaling, death receptor signaling, ILK signaling, IL-17A in gastric cells, IL-6 signaling, IL-8 signaling, the role of JAK1, JAK2, and TYK2 in interferon signaling, IL-9 signaling, HMGB1 signaling, NO production and ROS production in macrophages, whereas GSZ focused aryl hydrocarbon receptor signaling and apoptosis signaling in addition to those pathways induced by Guizhi, Shaoyao and Zhimu.

CONCLUSION

Although each single herb can affect some DPN-related functions and pathways, GSZ exerts more effects on DPN-related functions and pathways. The effects of GSZ on aryl hydrocarbon receptor signaling and apoptosis signaling pathways may be the key components of its total molecular mechanisms.

Prevalence and determinants of diabetic polyneuropathy in a sub-Saharan African referral hospital

BACKGROUND

Diabetic peripheral neuropathy is the commonest complication of diabetes mellitus, and a major cause of limb amputations. In general however, the magnitude of diabetic neuropathy in sub-Saharan Africans with diabetes has been less reliably quantified. We assessed the prevalence and determinants of diabetic polyneuropathy in hospital settings in Cameroon.

METHODS

We conducted a cross-sectional survey at the Douala Laquintinie Hospital, which is one of the main reference hospital in the economic capital of Cameroon (3 million populations). Participants included all patients with type 1 (T1DM) or type 2 (T2DM) diabetes who reported to the hospital regardless of the reason, during a 5-month recruitment period. Polyneuropathy was defined as diabetic in a patient with a Diabetic Neuropathy Examination score of >3/16 and/or a monofilament score of <5/9.

RESULTS

A total of 306 patients were recruited, including 196 women (64%) and 294 (96%) with T2DM. The mean (standard deviation) values were 59.8 (11.2) years for age and 8.4 (8.2) years for diabetes duration. Clinical signs of polyneuropathy were present in 102 (crude prevalence rate: 33.3%) patients. The polyneuropathy was symptomatic in 79/102 (77.4%) patients. Determinants of polyneuropathy were urban residence (p=0.02), infection with hepatitis C virus (p=0.002), infection with HIV (p=0.012) and presence of albuminuria (p=0.0001).

CONCLUSION

About one in three patients with diabetes reporting to the hospital in our setting has prevalent diabetes related polyneuropathy. This emphasizes the importance of routine implementation of therapeutic education and other measures to limit the complications.

Identifying Common Genetic Risk Factors of Diabetic Neuropathies

Type 2 diabetes mellitus (T2DM) is a global public health problem of epidemic proportions, with 60-70% of affected individuals suffering from associated neurovascular complications that act on multiple organ systems. The most common and clinically significant neuropathies of T2DM include uremic neuropathy, peripheral neuropathy, and cardiac autonomic neuropathy. These conditions seriously impact an individual's quality of life and significantly increase the risk of morbidity and mortality. Although advances in gene sequencing technologies have identified several genetic variants that may regulate the development and progression of T2DM, little is known about whether or not the variants are involved in disease progression and how these genetic variants are associated with diabetic neuropathy specifically. Significant missing heritability data and complex disease etiologies remain to be explained. This article is the first to provide a review of the genetic risk variants implicated in the diabetic neuropathies and to highlight potential commonalities. We thereby aim to contribute to the creation of a genetic-metabolic model that will help to elucidate the cause of diabetic neuropathies, evaluate a patient's risk profile, and ultimately facilitate preventative and targeted treatment for the individual.