Metanx in type 2 diabetes with peripheral neuropathy: a randomized trial

Corneal confocal microscopy detects early nerve regeneration after pharmacological and surgical interventions: Systematic review and meta-analysis

Corneal confocal microscopy (CCM) is an ophthalmic imaging technique that enables the identification of corneal nerve fibre degeneration and regeneration. To undertake a systematic review and meta-analysis of studies utilizing CCM to assess for corneal nerve regeneration after pharmacological and surgical interventions in patients with peripheral neuropathy. Databases (EMBASE [Ovid], PubMed, CENTRAL and Web of Science) were searched to summarize the evidence from randomized and non-randomized studies using CCM to detect corneal nerve regeneration after pharmacological and surgical interventions. Data synthesis was undertaken using RevMan web. Eighteen studies including 958 patients were included. CCM identified an early (1-8 months) and longer term (1-5 years) increase in corneal nerve measures in patients with peripheral neuropathy after pharmacological and surgical interventions. This meta-analysis confirms the utility of CCM to identify nerve regeneration following pharmacological and surgical interventions. It could be utilized to show a benefit in clinical trials of disease modifying therapies for peripheral neuropathy.

Diabetic Sensorimotor Polyneuropathy: An Overview on Epidemiology, Risk Factors, Classification, Diagnosis, and Treatment

Diabetic distal symmetric sensorimotor polyneuropathy (DSPN) is a common complication of diabetes with devastating consequences. Hyperglycaemia is the major aetiological factor, while emerging data demonstrate that cardiometabolic risk factors also contribute to its development. Diagnosis of DSPN involves interview of medical and neurological history, foot inspection, and sensory and motor function examination with specific tests such as temperature and pinprick perception for small nerve fibers, and vibration and light touch assessments for large nerve fibers. Management includes optimised glycaemic control, treatment of cardiovascular risk factors, and symptomatic treatment aiming at improving life quality. This article provides an overview on epidemiology, risk factors, classification, diagnosis and current treatment of DSPN.

Update on Treating Painful Diabetic Peripheral Neuropathy: A Review of Current US Guidelines with a Focus on the Most Recently Approved Management Options

Painful diabetic peripheral neuropathy (DPN) is a highly prevalent and disabling complication of diabetes that is often misdiagnosed and undertreated. The management of painful DPN involves treating its underlying cause via lifestyle modifications and intensive glucose control, targeting its pathogenesis, and providing symptomatic pain relief, thereby improving patient function and health-related quality of life. Four pharmacologic options are currently approved by the US Food and Drug Administration (FDA) to treat painful DPN. These include three oral medications (duloxetine, pregabalin, and tapentadol extended release) and one topical agent (capsaicin 8% topical system). More recently, the FDA approved several spinal cord stimulation (SCS) devices to treat refractory painful DPN. Although not FDA-approved specifically to treat painful DPN, tricyclic antidepressants, serotonin/norepinephrine reuptake inhibitors, gabapentinoids, and sodium channel blockers are common first-line oral options in clinical practice. Other strategies may be used as part of individualized comprehensive pain management plans. This article provides an overview of the most recent US guidelines for managing painful DPN, with a focus on the two most recently approved treatment options (SCS and capsaicin 8% topical system), as well as evidence for using FDA-approved and guideline-supported drugs and devices. Also discussed are unmet needs for this patient population, and evidence for potential future treatments for painful DPN, including drugs with novel mechanisms of action, electrical stimulation devices, and nutraceuticals.

Vitamin B6: a scoping review for Nordic Nutrition Recommendations 2023

Pyridoxal 5´-phosphate (PLP) is the main form of vitamin B6 in animal tissue and functions as a coenzyme for more than 160 different enzymatic reactions in the metabolism of amino acids, carbohydrates, lipids, and neurotransmitters. Estimated dietary intake of vitamin B6 and plasma PLP values differ a lot between studies, something which may be due to variable use of supplements, variations in dietary assessment and analytical methods. These factors make it difficult to achieve precise data for setting a correct recommended intake of vitamin B6. In addition, a plasma PLP concentration of 30 nmol/L is considered to be sufficient and the current recommendations for vitamin B6 intake is based on this concept. However, the metabolic marker for vitamin B6 status, HK ratio (HKr), starts to increase already when plasma PLP falls below 100 nmol/L and increases more steeply below 50 nmol/L, indicating biochemical deficiency. Consequently, a plasma PLP concentration of 30 nmol/L, may be too low as a marker for an adequate vitamin B6 status.

Novel therapeutical approaches based on neurobiological and genetic strategies for diabetic polyneuropathy - A review

BACKGROUND

Neuropathy is among the most often reported consequences of diabetes and the biggest cause of morbidity and mortality in people suffering from this life-long disease. Although different therapeutic methods are available for diabetic neuropathy, it is still the leading cause of limb amputations, and it significantly decreases patients' quality of life.

AIM

This study investigates potential novel therapeutic options that could ameliorate symptoms of DN.

METHODOLOGY

Research and review papers from the last 10 years were taken into consideration.

RESULTS

There are various traditional drugs and non-pharmacological methods used to treat this health condition. However, the research in the area of pathogenic-oriented drugs in the treatment of DN showed no recent breakthroughs, mostly due to the limited evidence about their effectiveness and safety obtained through clinical trials. Consequently, there is an urgent demand for the development of novel therapeutic options for diabetic neuropathy.

CONCLUSION

Some of the latest novel diagnostic methods for diagnosing diabetic neuropathy are discussed as well as the new therapeutic approaches, such as the fusion of neuronal cells with stem cells, targeting gene delivery and novel drugs.

Lower serum branched-chain amino acid catabolic intermediates are predictive signatures specific to patients with diabetic foot

Diabetic foot (DF) is one of the serious chronic complications of diabetes. Accurate prediction of the risk of DF may take timely intervention measures to prevent its occurrence. The understanding of metabolomic changes in the progression of diabetes to DF may reveal new targets for interventions. We hypothesized that changes in metabolic pathways during DF would lead to changes in the metabolic profile, which could be predictive signature specific to it. In the present study, 43 participants with type 2 diabetes mellitus (T2DM), 32 T2DM participants with DF (T2DM-F), and 36 healthy subjects were enrolled and their serum samples were used for targeted and nonpolar metabolic analysis with liquid chromatography-tandem mass spectrometry. Differential metabolites related to T2DM-F were discovered in metabolomic analysis. Lasso machine learning regression model, random forest algorithm, causal mediation analysis, disease risk assessment, and clinical decision model were carried out. T2DM and T2DM-F groups could be distinguished with the healthy control group. The differential metabolites were all enriched in alpha-linolenic acid and linoleic acid metabolic pathways including arachidonic acid, docosapentaenoic-acid 22N-6, and docosahexaenoic-acid, which were significantly lower in the T2DM and T2DM-F groups compared with the healthy control group. The differential metabolites in T2DM-F vs T2DM groups were enriched to branched-chain amino acid (BCAA) catabolic pathways involving in methylmalonic acid, succinic acid, 3-methyl-2-oxovaleric acid, and ketoleucine, which were the BCAA catabolic intermediates and significantly lower in the T2DM-F compared with the T2DM group except for succinic acid. We reveal a new set of predictive signatures and associate the lower BCAA catabolic intermediates with the progression from T2DM to T2DM-F.

How vitamins act as novel agents for ameliorating diabetic peripheral neuropathy: A comprehensive overview

Diabetic peripheral neuropathy (DPN) is a pervasive and incapacitating sequela of diabetes, affecting a significant proportion of those diagnosed with the disease, yet an effective treatment remains elusive. Vitamins have been extensively studied, emerging as a promising target for diagnosing and treating various systemic diseases, but their role in DPN is not known. This review collates and synthesizes knowledge regarding the interplay between vitamins and DPN, drawing on bibliographies from prior studies and relevant articles, and stratifying the therapeutic strategies from prophylactic to interventional. In addition, the clinical evidence supporting the use of vitamins to ameliorate DPN is also evaluated, underscoring the potential of vitamins as putative therapeutic agents. We anticipate that this review will offer novel insights for developing and applying vitamin-based therapies for DPN.

Folate and retinal vascular diseases

Folate, a pteroylglutamic acid derivative, participates in fundamental cellular metabolism. Homocysteine, an amino acid, serves as an intermediate of the methionine cycle and can be converted back to methionine. Hyperhomocysteinemia is a recognized risk factor for atherosclerotic and cardiovascular diseases. In recent decades, elevated plasma homocysteine levels and low folate status have been observed in many patients with retinal vascular diseases, such as retinal vascular occlusions, diabetic retinopathy, and age-related degeneration. Homocysteine-induced toxicity toward vascular endothelial cells might participate in the formation of retinal vascular diseases. Folate is an important dietary determinant of homocysteine. Folate deficiency is the most common cause of hyperhomocysteinemia. Folate supplementation can eliminate excess homocysteine in plasma. In in vitro experiments, folic acid had a protective effect on vascular endothelial cells against high glucose. Many studies have explored the relationship between folate and various retinal vascular diseases. This review summarizes the most important findings that lead to the conclusion that folic acid supplementation might be a protective treatment in patients with retinal vascular diseases with high homocysteine or glucose status. More research is still needed to validate the effect of folate and its supplementation in retinal vascular diseases.

Stimulating Results Signal a New Treatment Option for People Living With Painful Diabetic Neuropathy

BACKGROUND

Painful diabetic neuropathy (PDN) is a progressive condition that deprives many patients of quality of life. With limited treatment options available, successful pain management can be difficult to achieve.

METHODS

We reviewed results of recent data evaluating high frequency spinal cord stimulation (SCS).

RESULTS

from the SENZA-PDN randomized clinical trial (NCT03228420), the largest such trial to date, demonstrated 10-kHz spinal cord stimulation substantially reduced PDN refractory to conventional medical management along with improvements in health-related quality-of-life measures that were sustained over 12 months. These data supported the recent U.S. Food & Drug Administration (FDA) approval for 10-kHz SCS in PDN patients and contributed to the body of evidence on SCS available to health care professionals managing the effects of PDN.

CONCLUSION

High frequency spinal cord simulation appears to hold promise in treatment of painful diabetic neuropathy. We look forward to future works in the literature that will further elucidate these promising findings.

Where Art Thou O treatment for diabetic neuropathy: the sequel

INTRODUCTION

Having lived through a pandemic and witnessed how regulatory approval processes can evolve rapidly; it is lamentable how we continue to rely on symptoms/signs and nerve conduction as primary endpoints for clinical trials in DPN.

AREAS COVERED

Small (Aδ and C) fibers are key to the genesis of pain, regulate skin blood flow, and play an integral role in the development of diabetic foot ulceration but continue to be ignored. This article challenges the rationale for the FDA insisting on symptoms/signs and nerve conduction as primary endpoints for clinical trials in DPN.

EXPERT OPINION

Quantitative sensory testing, intraepidermal nerve fiber density, and especially corneal confocal microscopy remain an after-thought, demoted at best to exploratory secondary endpoints in clinical trials of diabetic neuropathy. If pharma are to be given a fighting chance to secure approval for a new therapy for diabetic neuropathy, the FDA needs to reassess the evidence rather than rely on 'opinion' for the most suitable endpoint(s) in clinical trials of diabetic neuropathy.

The Role of Vitamin B6 in Peripheral Neuropathy: A Systematic Review

INTRODUCTION

Vitamin B6 is a water-soluble vitamin that is naturally present in many foods and is accessible in many dietary supplements. The three natural forms are pyridoxine, pyridoxal, and pyridoxamine. Both vitamin B6 deficiency and high B6 intake have been described as risk factors for developing peripheral neuropathy (PN). The aim of this systematic review is to characterize and comprehensively describe B6-related PN.

METHOD

A systematic, computer-based search was conducted using the PubMed database. Twenty articles were included in this review.

RESULTS

Higher vitamin B6 levels, which usually occur following the taking of nutritional supplements, may lead to the development of a predominantly, if not exclusively, sensory neuropathy of the axonal type. After pyridoxine discontinuation, such patients subjectively report improved symptoms. However, although low vitamin B6 levels can be seen in patients suffering from peripheral neuropathy of various etiologies, there is no firm evidence that low B6 levels have a direct causal relationship with PN. Many studies suggest subjective improvement of neuropathy symptoms in patients suffering from PN of various etiologies after receiving B6 supplementation; however, no data about B6 administration as a monotherapy exist, only as part of a combination treatment, usually with other vitamins. Therefore, the potential therapeutic role of B6 cannot be confirmed to date. Supplementation with vitamin B6, even as part of a nutritional multivitamin supplement, has not been proven harmful at permitted daily doses in patients who already suffer from PN.

CONCLUSION

Current scientific evidence supports a neurotoxic role of B6 at high levels. Although some studies suggest that low B6 is also a potential risk factor, further studies in this area are needed.

Clinical Pathobiochemistry of Vitamin B12 Deficiency: Improving Our Understanding by Exploring Novel Mechanisms with a Focus on Diabetic Neuropathy

Vitamin B₁₂ (B₁₂) is an essential cofactor of two important biochemical pathways, the degradation of methylmalonic acid and the synthesis of methionine from homocysteine. Methionine is an important donor of methyl groups for numerous biochemical reactions, including DNA synthesis and gene regulation. Besides hematological abnormalities (megaloblastic anemia or even pancytopenia), a deficiency in B₁₂ may cause neurological symptoms, including symptoms resembling diabetic neuropathy. Although extensively studied, the underlining molecular mechanism for the development of diabetic peripheral neuropathy (DPN) is still unclear. Most studies have found a contribution of oxidative stress in the development of DPN. Detailed immunohistochemical investigations in sural nerve biopsies obtained from diabetic patients with DPN point to an activation of inflammatory pathways induced via elevated advanced glycation end products (AGE), ultimately resulting in increased oxidative stress. Similar results have been found in patients with B₁₂ deficiency, indicating that the observed neural changes in patients with DPN might be caused by cellular B₁₂ deficiency. Since novel results show that B₁₂ exerts intrinsic antioxidative activity in vitro and in vivo, B₁₂ may act as an intracellular, particularly as an intramitochondrial, antioxidant, independent from its classical, well-known cofactor function. These novel findings may provide a rationale for the use of B₁₂ for the treatment of DPN, even in subclinical early states.

Oxidative Stress in Diabetic Peripheral Neuropathy: Pathway and Mechanism-Based Treatment

Diabetic peripheral neuropathy (DPN) is a major complication of diabetes mellitus with a high incidence. Oxidative stress, which is a crucial pathophysiological pathway of DPN, has attracted much attention. The distortion in the redox balance due to the overproduction of reactive oxygen species (ROS) and the deregulation of antioxidant defense systems promotes oxidative damage in DPN. Therefore, we have focused on the role of oxidative stress in the pathogenesis of DPN and elucidated its interaction with other physiological pathways, such as the glycolytic pathway, polyol pathway, advanced glycosylation end products, protein kinase C pathway, inflammation, and non-coding RNAs. These interactions provide novel therapeutic options targeting oxidative stress for DPN. Furthermore, our review addresses the latest therapeutic strategies targeting oxidative stress for the rehabilitation of DPN. Antioxidant supplements and exercise have been proposed as fundamental therapeutic strategies for diabetic patients through ROS-mediated mechanisms. In addition, several novel drug delivery systems can improve the bioavailability of antioxidants and the efficacy of DPN.

l-Methylfolate in Diabetic Peripheral Neuropathy: A Narrative Review

OBJECTIVE

One of the most frequently occurring complications of diabetes mellitus is peripheral neuropathy. Despite the painful symptoms associated with diabetic peripheral neuropathy (DPN), the current treatment landscape focuses on managing symptoms without addressing the underlying causes of DPN. This narrative review describes the mechanistic effects and clinical trial data supporting the use of l-methylfolate calcium (LMF), the bioactive form of folate, which is available in the United States as a prescription medical food that also contains other B vitamins for the dietary management of DPN.

METHODS

Preclinical and clinical trial data evaluating the impact of LMF on DPN was identified using PubMed searches for articles published between 2010 and 2023. Search terms included: folate, l-methylfolate, diabetes, neuropathy, and neuropathic pain. Additionally, a literature search was conducted to identify studies related to LMF, genetic polymorphisms, and DPN pathophysiology.

RESULTS

Several studies show that the C677T variant of the methylenetetrahydrofolate reductase (MTHFR) gene is linked to greater risk of DPN than other MTHFR variants due to its inhibitory effects on several folic acid metabolic pathways. One double-blind, randomized controlled trial, five open-label studies, and one retrospective study found that LMF has a significant beneficial effect on DPN that extends beyond symptomatic relief to include modulating the underlying pathophysiology that leads to the progression and symptoms of DPN. LMF also significantly improves patient quality of life, with minimal adverse effects.

CONCLUSION

Preclinical and clinical studies have found that LMF can be used to treat the underlying causes of DPN and provide long-lasting symptomatic relief.

Efficacy of mecobalamin (vitamin B12) in the treatment of long-term pain in women diagnosed with fibromyalgia: protocol for a randomised, placebo-controlled trial

INTRODUCTION

Fibromyalgia causes long-term pain. It affects at least 2% of the population, the majority being women. In addition, extended symptoms corresponding to vitamin B12 deficiency occur. Findings from several studies have indicated that vitamin B12 may be a possible treatment for pain in fibromyalgia. The aim of the proposed study is to evaluate whether vitamin B12 decreases pain sensitivity and the experience of pain (ie, hyperalgesia and allodynia) in women with fibromyalgia.

METHODS AND ANALYSIS

The study is a randomised, placebo-controlled, single-blind, clinical trial with two parallel groups which are administered mecobalamin (vitamin B12) or placebo over 12 weeks. 40 Swedish women aged 20-70 years with an earlier recorded diagnosis of fibromyalgia are randomised into the placebo group or the treatment group, each consisting of 20 participants. Outcomes consist of questionnaires measured at baseline and after 12 weeks of treatment. A final re-evaluation will then follow 12 weeks after treatment ends. The primary outcome is tolerance time, maximised to 3 min, which is assessed using the cold pressor test. In order to broaden the understanding of the lived experience of participants, qualitative interviews will be conducted using a phenomenological approach on a lifeworld theoretical basis (reflective lifeworld research approach).

ETHICS AND DISSEMINATION

The protocol for the study is approved by the local ethical committee at Linkoping (EPM; 2018/294-31, appendices 2019-00347 and 2020-04482). The principles of the Helsinki Declaration are followed regarding oral and written consent to participate, confidentiality and the possibility to withdraw participation from the study at any time. The results will primarily be communicated through peer-reviewed journals and conferences.

TRIAL REGISTRATION NUMBER

NCT05008042.

Neurological Implications of Vitamin B12 Deficiency in Diet: A Systematic Review and Meta-Analysis

Background: Vitamin B12 is one of the most important B-Vitamins that the human body needs on a daily basis, the lack of which can precipitate several neurological issues. Objectives: This systematic aimed to investigate the neurological implications of Vitamin B12 deficiency and the effects when B12 levels were corrected in susceptible individuals. Methods: The databases PubMed-MEDLINE, Web of Science, Cochrane, and Scopus were all searched using pertinent keywords, reference searches, and citation searches. The terms used to access the database were “Cognition”, “Dietary patterns”, “Neurology”, “Nutritional profile”, and “Vitamin B12”. Results: Vitamin B12 was shown to noticeably improve cognition and other neurological parameters in the short term in older adults and the short-to-medium term in children; however, there was no perceived increase/improvement when the Vitamin was administered in the longer term, either alone or in conjunction with other similar nutritional interventions. Conclusion: Vitamin B12’s role in the improvement of neurological functions over a long-term period remains somewhat inconclusive to date, as the majority of our selected control trials did not display much correlation between the two factors. However, Vitamin B12 did improve cognition levels in both children and older adults over a short course of administration.

Are herbal medicines alone or in combination for diabetic peripheral neuropathy more effective than methylcobalamin alone? A systematic review and meta-analysis

BACKGROUND AND PURPOSE

In Asian countries, herbal medicines have been used to treat diabetic peripheral neuropathy (DPN) as an adjunctive therapy. This review aims to assess the effectiveness and safety of herbal medicines for the treatment of DPN.

METHODS

A literature search was conducted on PubMed, Embase, CENTRAL, Scopus, CINAHL, CNKI, DBPIA, and OASIS for randomized controlled trials that evaluated the effects of herbal medicines on DPN. The oral methylcobalamin administered group was selected as the control. The primary outcome measure was nerve conduction velocity (NCV), and the secondary outcome measure was the total efficacy rate (TER). The methodological quality of the included studies was assessed using the Cochrane risk of bias tool. A meta-analysis was conducted using Review Manager 5.4.1 software.

RESULTS

Seventy-two RCTs with a total of 6260 patients were included. The meta-analysis showed that herbal medicine and co-administration of herbal medicine and methylcobalamin (CHM) treatment for DPN significantly increased the sensory nerve conduction velocity (SNCV) and motor nerve conduction velocity (MNCV) of the median and common peroneal nerves than methylcobalamin treatment alone. Herbal medicine and CHM treatment for DPN also significantly improved the TER compared to the control group. Herbal medicine and CHM treatment was found to be relatively safe.

CONCLUSION

Our study suggests that herbal medicine and CHM might be more effective than methylcobalamin alone in the management of DPN. Further rigorous studies should be conducted to make more definite conclusions.

The Influence of Dietary Supplementations on Neuropathic Pain

Neuropathic pain is defined as pain caused by a lesion or disease of the somatosensory nervous system and affects 7-10% of the worldwide population. Neuropathic pain can be induced by the use of drugs, including taxanes, thus triggering chemotherapy-induced neuropathic pain or as consequence of metabolic disorders such as diabetes. Neuropathic pain is most often a chronic condition, and can be associated with anxiety and depression; thus, it negatively impacts quality of life. Several pharmacologic approaches exist; however, they can lead numerous adverse effects. From this perspective, the use of nutraceuticals and diet supplements can be helpful in relieve neuropathic pain and related symptoms. In this review, we discuss how diet can radically affect peripheral neuropathy, and we focus on the potential approaches to ameliorate this condition, such as the use of numerous nutritional supplements or probiotics.

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

CONTEXT

Diabetic peripheral neuropathy (DPN) is a common complication.

OBJECTIVE

To re-evaluate the role of vitamin B supplementation on reducing the signs and symptoms of DPN.

DATA SOURCES

Electronic databases such as PubMed, Cochrane Library, and Medline.

DATA EXTRACTION

An Excel spreadsheet was used to report the extracted relevant data.

DATA ANALYSIS

Fourteen randomized controlled trials were selected, comprising a pooled sample of 997 study subjects. The pooled odds ratio values were 3.1 (95%CI, 1.197-8.089) and 3.04 (95%CI, 1.556-5.937) for pain and dysesthesia outcomes, respectively. For the amplitude change in electromyography of the sensory sural nerve, the weighted difference from 2 studies was 0.37 (95%CI, 0.034-0.709) in favor of intervention. Peak latency changes were in favor of the intervention group. Two studies yielded a weighted difference of 0.571 (95%CI, 0.310-0.831) for the velocity outcome in favor of intervention. Unlike the fibular nerve, the electromyographic motor outcomes of the tibial nerve were in favor of vitamin B supplementation.

CONCLUSION

Vitamin B supplementation could improve many symptoms and signs of DPN.

Diagnostic Tools, Biomarkers, and Treatments in Diabetic polyneuropathy and Cardiovascular Autonomic Neuropathy

The various manifestations of diabetic neuropathy, including distal symmetric sensorimotor polyneuropathy (DSPN) and cardiovascular autonomic neuropathy (CAN), are among the most prevalent chronic complications of diabetes. Major clinical complications of diabetic neuropathies, such as neuropathic pain, chronic foot ulcers, and orthostatic hypotension, are associated with considerable morbidity, increased mortality, and diminished quality of life. Despite the substantial individual and socioeconomic burden, the strategies to diagnose and treat diabetic neuropathies remain insufficient. This review provides an overview of the current clinical aspects and recent advances in exploring local and systemic biomarkers of both DSPN and CAN assessed in human studies (such as biomarkers of inflammation and oxidative stress) for better understanding of the underlying pathophysiology and for improving early detection. Current therapeutic options for DSPN are (I) causal treatment, including lifestyle modification, optimal glycemic control, and multifactorial risk intervention, (II) pharmacotherapy derived from pathogenetic concepts, and (III) analgesic treatment against neuropathic pain. Recent advances in each category are discussed, including non-pharmacological approaches, such as electrical stimulation. Finally, the current therapeutic options for cardiovascular autonomic complications are provided. These insights should contribute to a broader understanding of the various manifestations of diabetic neuropathies from both the research and clinical perspectives.

Vitamin B for treating diabetic peripheral neuropathy - A systematic review

This systematic review assesses the effectiveness and safety of vitamin B supplements for the management of neuropathy in people with diabetes.

METHODS

Several databases including, the Cochrane Neuromuscular Specialised Register, CENTRAL, MEDLINE, Embase and CINAHL Plus were searched from their inception until May 2020.

RESULTS

Five studies were eligible to be included in this review with a total of 348 participants. Overall, the evidence is too uncertain to draw conclusions on the effects of B vitamins in people with DPN.

CONCLUSION

It is uncertain whether vitamin B supplements change pain intensity or impairment in the short or long term in people with DPN.

Exercise and Nutraceuticals: Eminent approach for Diabetic Neuropathy

Diabetic neuropathy is an incapacitating chronic pathological condition that encompasses a large group of diseases and manifestations of nerve damage. It affects approximately 50% of patients with diabetes mellitus. Autonomic, sensory, and motor neurons are affected. Disabilities are severe, along with poor recovery and diverse pathophysiology. Physical exercise and herbal-based therapies have the potential to decrease the disabilities associated with diabetic neuropathy. Aerobic exercises like walking, weight lifting, the use of nutraceuticals and herbal extracts are found to be effective. Literature from the public domain was studied emphasizing various beneficial effects of different exercises, use of herbal and nutraceuticals for their therapeutic action in diabetic neuropathy. Routine exercises and administration of herbal and nutraceuticals, either the extract of plant material containing the active phytoconstituent or isolated phytoconstituent at safe concentration, have been shown to have promising positive action in the treatment of diabetic neuropathy. Exercise has shown promising effects on vascular and neuronal health and has proven to be well effective in the treatment as well as prevention of diabetic neuropathy by various novel mechanisms, including herbal and nutraceuticals therapy is also beneficial for the condition. They primarily show the anti-oxidant effect, secretagogue, anti-inflammatory, analgesic, and neuroprotective action. Severe adverse events are rare with these therapies. The current review investigates the benefits of exercise and nutraceutical therapies in the treatment of diabetic neuropathy.

Drug-Induced Peripheral Neuropathy: A Narrative Review

Background

Peripheral neuropathy is a painful condition deriving from many and varied etiologies. Certain medications have been implicated in the iatrogenic development of Drug Induced Peripheral Neuropathy (DIPN) and include chemotherapeutic agents, antimicrobials, cardiovascular drugs, psychotropic, anticonvulsants, among others. This review synthesizes current clinical concepts regarding the mechanism, common inciting medications, and treatment options for drug-induced peripheral neuropathy.

Methods

The authors undertook a structured search of bibliographic databases for peer-reviewed research literature using a focused review question and inclusion/exclusion criteria. The most relevant and up to date research was included.

Results

Drug-induced peripheral neuropathy is a common and painful condition caused by many different and frequently prescribed medications. Most often, DIPN is seen in chemotherapeutic agents, antimicrobials, cardiovascular drugs, psychotropic, and anticonvulsant drugs. Certain drugs exhibit more consistent neuropathic side effects, such as the chemotherapeutic compounds, but others are more commonly prescribed by a larger proportion of providers, such as the statins. DIPN is more likely to occur in patients with concomitant risk factors such as preexisting neuropathy, diabetes, and associated genetically predisposing diseases. DIPN is often difficult to treat, however medications including duloxetine, and gabapentin are shown to reduce neuropathic pain. Advanced techniques of neuromodulation offer promise though further randomized and controlled studies are needed to confirm efficacy.

Conclusion

Awareness of the drugs covered in this review and their potential for adverse neuropathic effect is important for providers caring for patients who report new onset symptoms of pain, paresthesia, or weakness. Prevention of DIPN is especially important because treatment often proves challenging. While many pharmacologic therapies have demonstrated analgesic potential in the pain caused by DIPN, many patients remain refractive to treatment. More studies are needed to elucidate the effectiveness of interventional, neuromodulating therapies.

Nutritional Supplements for the Treatment of Neuropathic Pain

Neuropathic pain affects 7-10% of the population and is often ineffectively and incompletely treated. Although the gold standard for treatment of neuropathic pain includes tricyclic antidepressants (TCAs), serotonin-noradrenaline reuptake inhibitors, and anticonvulsants, patients suffering from neuropathic pain are increasingly turning to nonpharmacologic treatments, including nutritional supplements for analgesia. So-called "nutraceuticals" have garnered significant interest among patients seeking to self-treat their neuropathic pain with readily available supplements. The supplements most often used by patients include vitamins such as vitamin B and vitamin D, trace minerals zinc and magnesium, and herbal remedies such as curcumin and St. John's Wort. However, evidence surrounding the efficacy and mechanisms of these supplements in neuropathic pain is limited, and the scientific literature consists primarily of preclinical animal models, case studies, and small randomized controlled trials (RCTs). Further exploration into large randomized controlled trials is needed to fully inform patients and physicians on the utility of these supplements in neuropathic pain. In this review, we explore the basis behind using several nutritional supplements commonly used by patients with neuropathic pain seen in rheumatology clinics.

B vitamins as a treatment for diabetic pain and neuropathy

WHAT IS KNOWN AND OBJECTIVE

B vitamin therapy is a common treatment for diabetic pain and neuropathy, yet its use remains controversial in patients lacking B vitamin deficiencies. The aim of this review was to summarize the current evidence for the efficacy of B vitamin therapy in diabetic patients with neuropathy.

COMMENT

We screened the English literature for clinical studies evaluating B vitamins as a therapy for pain and neuropathy in diabetic patients. We selected 43 relevant studies for qualitative analysis based on our selection criteria. Our survey of the literature revealed substantive heterogeneity with respect to efficacies of reported outcomes, as well as study design. Most beneficial outcomes were reported against baseline measures, with few positive comparisons against placebo. This highlights the need for larger, placebo-controlled studies.

WHAT IS NEW AND CONCLUSION

B vitamins should be considered a plausible therapy for diabetic neuropathy, but its overall efficacy remains uncertain and requires further study.

Microvascular Dysfunction in Diabetes Mellitus and Cardiometabolic Disease

This review takes an inclusive approach to microvascular dysfunction in diabetes mellitus and cardiometabolic disease. In virtually every organ, dynamic interactions between the microvasculature and resident tissue elements normally modulate vascular and tissue function in a homeostatic fashion. This regulation is disordered by diabetes mellitus, by hypertension, by obesity, and by dyslipidemia individually (or combined in cardiometabolic disease), with dysfunction serving as an early marker of change. In particular, we suggest that the familiar retinal, renal, and neural complications of diabetes mellitus are late-stage manifestations of microvascular injury that begins years earlier and is often abetted by other cardiometabolic disease elements (eg, hypertension, obesity, dyslipidemia). We focus on evidence that microvascular dysfunction precedes anatomic microvascular disease in these organs as well as in heart, muscle, and brain. We suggest that early on, diabetes mellitus and/or cardiometabolic disease can each cause reversible microvascular injury with accompanying dysfunction, which in time may or may not become irreversible and anatomically identifiable disease (eg, vascular basement membrane thickening, capillary rarefaction, pericyte loss, etc.). Consequences can include the familiar vision loss, renal insufficiency, and neuropathy, but also heart failure, sarcopenia, cognitive impairment, and escalating metabolic dysfunction. Our understanding of normal microvascular function and early dysfunction is rapidly evolving, aided by innovative genetic and imaging tools. This is leading, in tissues like the retina, to testing novel preventive interventions at early, reversible stages of microvascular injury. Great hope lies in the possibility that some of these interventions may develop into effective therapies.

Vitamin B12 Supplementation in Diabetic Neuropathy: A 1-Year, Randomized, Double-Blind, Placebo-Controlled Trial

AIM

To investigate the effect of normalizing vitamin B12 (B12) levels with oral B12 (methylcobalamin) 1000 μg/day for one year in patients with diabetic neuropathy (DN).

PATIENTS AND METHODS

In this prospective, double-blind, placebo-controlled trial, 90 patients with type 2 diabetes on metformin for at least four years and both peripheral and autonomic DN were randomized to an active treatment group (n = 44) receiving B12 and a control group (n = 46) receiving a placebo. All patients had B12 levels less than 400 pmol/L. Subjects underwent measurements of sural nerve conduction velocity (SNCV), sural nerve action potential (amplitude) (SNAP), and vibration perception threshold (VPT), and they performed cardiovascular autonomic reflex tests (CARTs: mean circular resultant (MCR), Valsalva test, postural index, and orthostatic hypotension). Sudomotor function was assessed with the SUDOSCAN that measures electrochemical skin conductance in hands and feet (ESCH and ESCF, respectively). We also used the Michigan Neuropathy Screening Instrument Questionnaire and Examination (MNSIQ and MNSIE, respectively) and questionnaires to evaluate quality of life (QoL) and level of pain (pain score).

RESULTS

B12 levels increased from 232.0 ± 71.8 at baseline to 776.7 ± 242.3 pmol/L at follow-up, p < 0.0001, in the active group but not in the control group. VPT, MNSIQ, QoL, pain score, SNCV, SNAP, and ESCF significantly improved in the active group (p < 0.001, p = 0.002, p < 0.0001, p < 0.000, p < 0.0001, p < 0.0001, and p = 0.014, respectively), whereas CARTS and MNSIE improved but not significantly. MCR, MNSIQ, SNCV, SNAP, and pain score significantly deteriorated in the control group (p = 0.025, p = 0.017, p = 0.045, p < 0.0001, and p < 0.0001, respectively).

CONCLUSIONS

The treatment of patients with DN with 1 mg of oral methylcobalamin for twelve months increased plasma B12 levels and improved all neurophysiological parameters, sudomotor function, pain score, and QoL, but it did not improve CARTS and MNSIE.

Management of Neuropathic Pain in Polyneuropathy

PURPOSE OF REVIEW

Many polyneuropathies cause significant neuropathic pain, resulting in substantial morbidity and reduced quality of life. Appropriate management is crucial for maintaining quality of life for patients with painful polyneuropathies. The US Food and Drug Administration (FDA) has only approved one new drug for painful diabetic neuropathy in the past decade, a topical capsaicin patch that was initially approved for the treatment of postherpetic neuralgia in 2009. Gabapentinoids and serotonin norepinephrine reuptake inhibitors (SNRIs) continue to have an advantage in safety profiles and efficacy. Other antiepileptic medications remain second-line agents because of fewer studies documenting efficacy.

RECENT FINDINGS

This article reviews recent literature on complementary and pharmacologic therapies for the management of painful polyneuropathies. Exercise has emerged as an important therapeutic tool and may also improve the underlying polyneuropathy in the setting of obesity, metabolic syndrome, and diabetes.

SUMMARY

The approach to management of painful polyneuropathies is multifactorial, using both pharmacologic and nonpharmacologic measures to improve pain severity and patient quality of life.

Efficacy and Safety of Mecobalamin on Peripheral Neuropathy: A Systematic Review and Meta-Analysis of Randomized Controlled Trials

Objectives: To assess the efficacy and safety of mecobalamin on peripheral neuropathy. Background: Mecobalamin is an active form of vitamin B12 that has been suggested to be beneficial in improving nerve conduction and neuropathic pain symptoms. Although it is already widely used in Asia for the treatment of peripheral neuropathies, its efficacy remains unclear. Methods: Relevant electronic databases were systematically searched for randomized controlled trials investigating the efficacy and safety of mecobalamin on peripheral neuropathy, from inception through December 2019. Study selection, data extraction, and quality assessment were performed independently by two reviewers. The clinical therapeutic efficacy, pain score, neuropathic symptom score, nerve conduction velocities (NCVs), and adverse events of mecobalamin were assessed and were pooled by using a random-effects model. Heterogeneity was assessed by I² and chi-squared tests. Results: Fifteen studies with 1707 peripheral neuropathy patients caused by diabetic peripheral neuropathy and herpetic neuropathy were included. Based on Cochrane's risk of bias criteria, most of the included studies (11/15, 73%) were rated high risk of bias, whereas 20% and 7% were rated some concerns and low risk of bias, respectively. In terms of the proportion of patients achieving clinical therapeutic efficacy, mecobalamin alone (risk ratio [RR] = 1.17; 95% confidence interval [CI] 1.03-1.33) and mecobalamin in combination (RR = 1.32; 95% CI 1.21-1.45) are more effective than active control. For NCV outcomes, only mecobalamin combination treatment was effective. Neither mecobalamin alone nor mecobalamin in combination is effective on the pain score and neuropathic symptom outcomes. No serious adverse events associated with mecobalamin were reported during the treatment periods. Conclusion: Our findings indicate that mecobalamin in combination may be effective in improving clinical therapeutic efficacy and NCV outcomes for peripheral neuropathy patients, but the evidence is not clear for mecobalamin alone. More high-quality studies are required to confirm this finding.

Nutritional and medical food therapies for diabetic retinopathy

Diabetic retinopathy (DR) is a form of microangiopathy. Reducing oxidative stress in the mitochondria and cell membranes decreases ischemic injury and end-organ damage to the retina. New approaches are needed, which reduce the risk and improve the outcomes of DR while complementing current therapeutic approaches. Homocysteine (Hcy) elevation and oxidative stress are potential therapeutic targets in DR. Common genetic polymorphisms such as those of methylenetetrahydrofolate reductase (MTHFR), increase Hcy and DR risk and severity. Patients with DR have high incidences of deficiencies of crucial vitamins, minerals, and related compounds, which also lead to elevation of Hcy and oxidative stress. Addressing the effects of the MTHFR polymorphism and addressing comorbid deficiencies and insufficiencies reduce the impact and severity of the disease. This approach provides safe and simple strategies that support conventional care and improve outcomes. Suboptimal vitamin co-factor availability also impairs the release of neurotrophic and neuroprotective growth factors. Collectively, this accounts for variability in presentation and response of DR to conventional therapy. Fortunately, there are straightforward recommendations for addressing these issues and supporting traditional treatment plans. We have reviewed the literature for nutritional interventions that support conventional therapies to reduce disease risk and severity. Optimal combinations of vitamins B1, B2, B6, L-methylfolate, methylcobalamin (B12), C, D, natural vitamin E complex, lutein, zeaxanthin, alpha-lipoic acid, and n-acetylcysteine are identified for protecting the retina and choroid. Certain medical foods have been successfully used as therapy for retinopathy. Recommendations based on this review and our clinical experience are developed for clinicians to use to support conventional therapy for DR. DR from both type 1 diabetes mellitus (T1DM) and type 2 diabetes mellitus (T2DM) have similar retinal findings and responses to nutritional therapies.

Diabetic Polyneuropathy - Advances in Diagnosis and Intervention Strategies

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

[Adjuvant therapy of pain syndromes: possibilities of using nucleotides]

Despite the variety of treatment options, pain syndromes are widespread in the population. Adjuvant methods, in particular vitamins and vitamin combinations, are widely used, along with nonsteroidal anti-inflammatory drugs, myorelaxants and anticonvulsants, by physicians of different specialties. In recent years, new drugs containing pyrimidine nucleotides (uridine monophosphate) were brought to market. The paper describes analgesic effects of uridine monophosphate and choline, possibilities of their simultaneous use in combination with vitamins to promote the recovery of damaged structured of the peripheral nervous system, including remyelination and neuroplasticity. It has been concluded that nucleotide complexes can be effectively used as adjuvant therapy of pain.

Associations between metformin use and vitamin B12 levels, anemia, and neuropathy in patients with diabetes: a meta-analysis

BACKGROUND

Metformin is first-line therapy for patients with diabetes. However, it may lower vitamin B₁₂ concentrations, which could have hematological or neurological implications. This meta-analyses reviewed all available studies on associations between metformin use and vitamin B₁₂ levels, anemia, and neuropathy in diabetic patients.

METHODS

PubMed, Web of Knowledge, Cochrane Library, and Embase were searched to identify all relevant studies published in English prior to March 2018. Pooled risk ratios (RRs) and 95% confidence intervals (CIs) were calculated for dichotomous outcomes and pooled mean differences (MDs) and 95% CIs were calculated for continuous outcomes.

RESULTS

Thirty-one studies were included in the meta-analyses. Compared with diabetic patients not taking metformin, patients taking metformin had a significantly higher risk of vitamin B₁₂ deficiency (RR 2.09; 95% CI 1.49, 2.93; P < 0.0001; I²  = 64%) and significantly lower serum vitamin B₁₂ concentrations (MD -63.70; 95% CI -74.35, -53.05] pM; P < 0.00001; I²  = 87%), which depended on dose and duration of treatment. Metformin use was also associated with significantly greater percentage decrease in serum vitamin B₁₂ concentrations from baseline in diabetic patients (MD -14.68%; 95% CI -17.98%, -11.39%; P < 0.00001; I²  = 33%). Analyses revealed no significant association between metformin use and the prevalence of anemia or neuropathy.

CONCLUSIONS

Metformin use led to significantly lowered vitamin B₁₂ concentrations and significantly higher risk of vitamin B₁₂ deficiency in diabetic patients. More quality studies are needed to explore the associations between metformin use and anemia and neuropathy in these patients. Annual vitamin B₁₂ assessment in diabetic patients taking metformin is recommended.

Emerging Biomarkers, Tools, and Treatments for Diabetic Polyneuropathy

Diabetic neuropathy, with its major clinical sequels, notably neuropathic pain, foot ulcers, and autonomic dysfunction, is associated with substantial morbidity, increased risk of mortality, and reduced quality of life. Despite its major clinical impact, diabetic neuropathy remains underdiagnosed and undertreated. Moreover, the evidence supporting a benefit for causal treatment is weak at least in patients with type 2 diabetes, and current pharmacotherapy is largely limited to symptomatic treatment options. Thus, a better understanding of the underlying pathophysiology is mandatory for translation into new diagnostic and treatment approaches. Improved knowledge about pathogenic pathways implicated in the development of diabetic neuropathy could lead to novel diagnostic techniques that have the potential of improving the early detection of neuropathy in diabetes and prediabetes to eventually embark on new treatment strategies. In this review, we first provide an overview on the current clinical aspects and illustrate the pathogenetic concepts of (pre)diabetic neuropathy. We then describe the biomarkers emerging from these concepts and novel diagnostic tools and appraise their utility in the early detection and prediction of predominantly distal sensorimotor polyneuropathy. Finally, we discuss the evidence for and limitations of the current and novel therapy options with particular emphasis on lifestyle modification and pathogenesis-derived treatment approaches. Altogether, recent years have brought forth a multitude of emerging biomarkers reflecting different pathogenic pathways such as oxidative stress and inflammation and diagnostic tools for an early detection and prediction of (pre)diabetic neuropathy. Ultimately, these insights should culminate in improving our therapeutic armamentarium against this common and debilitating or even life-threatening condition.

Effect of folate supplementation on insulin sensitivity and type 2 diabetes: a meta-analysis of randomized controlled trials

Background

Various mechanisms link higher total homocysteine to higher insulin resistance (IR) and risk of type 2 diabetes (T2D). Folate supplementation is recognized as a way to lower homocysteine. However, randomized controlled trials (RCTs) show inconsistent results on IR and T2D outcomes.

Objective

The aim of this study was to examine the effect of folate supplementation on IR and T2D outcomes.

Design

We conducted a systematic literature search in PubMed, Web of Science, and EMBASE and prior systematic reviews and meta-analyses and identified 29 RCTs (22,250 participants) that assessed the effect of placebo-controlled folate supplementation alone or in combination with other B vitamins on fasting glucose, insulin, homeostasis model assessment for insulin resistance (HOMA-IR), glycated hemoglobin (HbA1c), or risk of T2D. The meta-analysis was conducted using both random- and fixed-effects models to calculate weighted mean differences (WMDs) or risk ratios with 95% CIs. Subgroup analyses were conducted based on intervention type (folate alone or in combination with other B vitamins), as well as analysis based on population characteristics, duration, dose, and change in homocysteine.

Results

When compared with placebo, folate supplementation lowered fasting insulin (WMD: -13.47 pmol/L; 95% CI: -21.41, -5.53 pmol/L; P < 0.001) and HOMA-IR (WMD: -0.57 units; 95% CI: -0.76, -0.37 units; P < 0.0001), but no overall effects were observed for fasting glucose or HbA1c. Heterogeneity was low in all meta-analyses, and subgroup analysis showed no signs of effect modification except for change in homocysteine, with the most pronounced effects in trials with a change of >2.5 µmol/L. Changes in homocysteine after folate supplementation correlated with changes in fasting glucose (β = 0.07; 95% CI: 0.01, 0.14; P = 0.025) and HbA1c (β = 0.46; 95% CI: 0.06, 0.85; P = 0.02). Only 2 studies examined folate supplementation on risk of T2D, and they found no change in RR (pooled RR: 0.91; 95% CI: 0.80, 1.04; P = 0.16).

Conclusion

Folate supplementation might be beneficial for glucose homeostasis and lowering IR, but at present there are insufficient data to conclusively determine the effect on development of T2D. This trial was registered on the Prospero database as CRD42016048254.

Long-term treatment with metformin in type 2 diabetes and methylmalonic acid: Post hoc analysis of a randomized controlled 4.3year trial

AIMS

Metformin treatment is associated with a decrease of serum vitamin B12, but whether this reflects tissue B12 deficiency is controversial. We studied the effects of metformin on serum levels of methylmalonic acid (MMA), a biomarker for tissue B12 deficiency, and on onset or progression of neuropathy.

METHODS

In the HOME trial, 390 insulin-treated patients with type 2 diabetes were treated with metformin or placebo for 52months. In a post hoc analysis, we analyzed the association between metformin, MMA and a validated Neuropathy Score (NPS).

RESULTS

Metformin vs placebo increased MMA at the end of the study (95%CI: 0.019 to 0.055, p=0.001). Mediation analysis showed that the effect of metformin on the NPS consisted of a beneficial effect through lowering HbA1c (-0.020 per gram year) and an adverse effect through increasing MMA (0.042 per gram year), resulting in a non-significant net effect (0.032 per gram year, 95% CI: -0.121 to 0.182, p=0.34).

CONCLUSION

Metformin not only reduces serum levels of B12, but also progressively increases serum MMA. The increase of MMA in metformin users was associated with significant worsening of the NPS. These results provide further support that metformin-related B12 deficiency is clinically relevant. Monitoring of B12 in users of metformin should be considered.

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.

Vitamin B supplementation for diabetic peripheral neuropathy

Vitamin B12 deficiency has been associated with significant neurological pathology, especially peripheral neuropathy. This review aims to examine the existing evidence on the effectiveness of vitamin B12 supplementation for the treatment of diabetic peripheral neuropathy. A search of PubMed and the Cochrane Central Register of Controlled Trials for all relevant randomised controlled trials was conducted in December 2014. Any type of therapy using vitamin B12 or its coenzyme forms was assessed for efficacy and safety in diabetics with peripheral neuropathy. Changes in vibration perception thresholds, neuropathic symptoms and nerve conduction velocities, as well as the adverse effects of vitamin B12 therapy, were assessed. Four studies comprising 363 patients met the inclusion criteria. This review found no evidence that the use of oral vitamin B12 supplements is associated with improvement in the clinical symptoms of diabetic neuropathy. Furthermore, the majority of studies reported no improvement in the electrophysiological markers of nerve conduction.

Vitamin B12 is Found Sufficient in Newly Diagnosed Type 2 Diabetes in a Hospital Based Study

Background: Vitamin B12 deficiency may be related to peripheral neuropathy in people with type 2 diabetes mellitus (T2DM). Level of B12 in T2DM observed by many investigators showed variable results. Studies on vitamin B12 in T2DM are very limited in Bangladesh. Objectives: To observe serum vitamin B12 level in newly diagnosed T2DM patients. Methods: Observational cross-sectional study encompassing 50 newly diagnosed T2DM and 50 controls as per American Diabetes Association (ADA) criteria. Vitamin B12 and Hemoglobin A1c (HbA1c) were measured for all. Results: Both mean (492.46±28.82 vs. 346.48±19.65 pg/mL, mean±SEM; p=<0.001) and median (435.50 vs. 334.50 pg/mL) values of serum vitamin B12 were found to be higher in T2DM than those of controls. None of the diabetic subjects were found to be B12 deficient whereas 6 were borderline deficient; these frequencies were 7 and 11 respectively among the controls. Vitamin B12 level was statistically similar in patients with or without clinically evident peripheral neuropathy (mean±SEM; 523.48±39.39 vs. 441.84±38.76 pg/mL, p=0.172). B12 level showed positive correlation with fasting plasma glucose (FPG, r=0.285, p=0.061) and HbA1c (r=0.287, p= 0.043) in diabetes group but there was no correlation with body mass index (BMI). Conclusion: Vitamin B12 is found sufficient in newly diagnosed Bangladeshi T2DM patients.