Vitamin D for the treatment of painful diabetic neuropathy

The Importance of Bright Spotty Lesions on Magnetic Resonance Imaging in Predicting Chronic Neuropathic Pain in Myelitis

Background/Objectives: Chronic neuropathic pain (CNP) stands as one of the most debilitating complications in patients with myelitis owing to its challenging management. Bright spotty lesions (BSLs) are frequently observed in neuromyelitis optica spectrum disorder (NMOSD), but few reports have discussed CNP in myelitis. We aim to demonstrate that BSLs could be one of the potential prognostic factors for CNP development in myelitis. Methods: We examined 63 patients diagnosed with myelitis. Patients were categorized into CNP and non-CNP groups. We assessed the severity of clinical symptoms and the oral steroid dose administered after pulse therapy. Spine magnetic resonance imaging (MRI) of each patient was reviewed to analyze the characteristics of myelitis. Serological and cerebrospinal fluid (CSF) findings were also examined to confirm the etiology. Results: CNP was observed in 27 patients (42.9%). The mean onset age of patients with CNP was 45.26 ± 14.16 years. The MRI lesions exhibited more enhanced features and bright spotty lesions (BSLs) in the CNP group (χ2 test, p < 0.05). Patients with CNP received a lower oral steroid dose during the first month after symptom onset (χ2 test, p < 0.05). Multivariate logistic regression analysis revealed that patients with CNP exhibited significant BSLs in their myelitis lesions on spine MRI (OR 4.965; 95% CI, 1.282 to 19.235, p = 0.02). Conclusions: Although the exact mechanism remains unknown, the presence of BSLs on spine MRI could serve as an independent prognostic factor for CNP development. Additionally, our study suggests that lower oral steroid doses administered immediately after symptom onset are associated with CNP development. Further investigation with a larger cohort is warranted to validate our findings.

Vitamin D Supplementation: Shedding Light on the Role of the Sunshine Vitamin in the Prevention and Management of Type 2 Diabetes and Its Complications

As the incidence of type 2 diabetes mellitus (T2DM) continues to increase globally, researchers are keen to investigate various interventions to mitigate its impact. Among these, vitamin D supplementation has attracted significant attention due to its influence on insulin secretion from the pancreas and insulin receptors in body cells. A substantial body of evidence indicates that vitamin D supplementation can reduce low-grade inflammation, a critical factor in developing insulin resistance. In addition, vitamin D aids in sustaining low resting concentrations of reactive oxygen species and free radicals, normalizes Ca2+ signaling, diminishes the expression of cytokines that are pro-inflammatory, and enhances the production of cytokines that are anti-inflammatory. This review discusses the effects of vitamin D on the glycemic control of individuals with T2DM and evaluates the impact of vitamin D supplementation on glycemic markers in this population. The investigation employs a comprehensive analysis of the existing literature with a special focus on recent studies published in the past decade. Based on the findings in the literature, it can be concluded that vitamin D supplementation alongside anti-diabetic medications may enhance glycemic control and potentially reduce the risk of diabetic complications. The evidence supports the notion that vitamin D supplementation can be a valuable addition to pharmacological agents for the management of T2DM, potentially enhancing glycemic control and overall health outcomes in affected individuals.

Update on Biomarkers of Chronic Inflammatory Processes Underlying Diabetic Neuropathy

There is an increasing prevalence of diabetes mellitus (DM), particularly type 2 DM (T2DM), and its associated complications. T2DM is linked to insulin resistance, chronic inflammation, and oxidative stress, which can lead to both macrovascular and microvascular complications, including peripheral diabetic neuropathy (PDN). Inflammatory processes play a key role in the development and progression of T2DM and its complications, with specific markers like C-reactive protein (CRP), interleukins (ILs), and tumor necrosis factor (TNF)-α being associated with increased risk. Other key inflammatory markers such as nuclear factor kappa B (NF-κB) are activated under hyperglycemic and oxidative stress conditions and contribute to the aggravation of PDN by regulating inflammatory gene expression and enhancing endothelial dysfunction. Other important roles in the inflammatory processes are played by Toll-like receptors (TLRs), caveolin 1 (CAV1), and monocyte chemoattractant protein 1 (MCP1). There is a relationship between vitamin D deficiency and PDN, highlighting the critical role of vitamin D in regulating inflammation and immune responses. The involvement of macrophages in PDN is also suspected, emphasizing their role in chronic inflammation and nerve damage in diabetic patients. Vitamin D supplementation has been found to reduce neuropathy severity, decrease inflammatory markers, and improve glycemic control. These findings suggest that addressing vitamin D deficiency could offer therapeutic benefits for PDN. These molecular pathways are critical in understanding the pathogenesis of DM complications and may offer potential biomarkers or therapeutic targets including anti-inflammatory treatments, vitamin D supplementation, macrophage phenotype modulation, and lifestyle modifications, aimed at reducing inflammation and preventing PDN. Ongoing and more extensive clinical trials with the aim of investigating anti-inflammatory agents, TNF-α inhibitors, and antioxidants are needed to advance deeper into the understanding and treatment of painful diabetic neuropathy.

The Role of Vitamin D in the Treatment of Carpal Tunnel Syndrome: Clinical and Electroneuromyographic Responses

Carpal tunnel syndrome (CTS) is the most common cause of peripheral compressive neuropathy and consists of compression of the median nerve in the wrist. Although there are several etiologies, idiopathic is the most prevalent origin, and among the forms of treatment for CTS, conservative is the most indicated. However, despite the high prevalence in and impact of this syndrome on the healthcare system, there are still controversies regarding the best therapeutic approach for patients. Therefore, noting that some studies point to vitamin D deficiency as an independent risk factor, which increases the symptoms of the syndrome, this study evaluated the role of vitamin D supplementation and its influence on pain control, physical examination and response electroneuromyography to conservative treatment of carpal tunnel syndrome. For this, the sample consisted of 14 patients diagnosed with CTS and hypovitaminosis D, who were allocated into two groups. The control group received corticosteroid treatment, while the experimental group received corticosteroid treatment associated with vitamin D. Thus, from this study, it can be concluded that patients who received vitamin D, when compared to those who did not receive it, showed improvement in the degree of pain intensity, a reduction in symptom severity and an improvement in some electroneuromyographic parameters.

Chinese Guidelines for Medical Nutrition Therapy for Patients with Diabetes (2022 Edition)

Medical nutrition therapy (MNT) is the foundation of the comprehensive treatment of patients with diabetes. In 2010, the Chinese Clinical Nutritionist Center of the Chinese Medical Doctor Association developed the first Chinese guideline on MNT for patients with diabetes, and it was updated in 2015. Since then, new evidence has emerged in the field of MNT and metabolic therapy in patients with diabetes. The Nutrition and Metabolic Management Branch of the China International Exchange and Promotive Association for Medical and Health Care organized a team of experts from related institutions, including the Clinical Nutrition Branch of the Chinese Nutrition Society, Chinese Diabetes Society, Chinese Society for Parenteral and Enteral Nutri-tion, and Chinese Clinical Nutritionist Center of the Chinese Medical Doctor Association. Their task was to develop the Chinese Guidelines of Medical Nutrition Therapy in Diabetes (2022 Edition) in accordance with the requirements of the Guidelines for the Formulation/Revision of Clinical Guidelines in China (2022 Edition) by combining the questions raised and evidence gathered in clinical practices in China, to guide and standardize the clinical MNT.

Multimodal Approaches in the Treatment of Chronic Peripheral Neuropathy-Evidence from Germany

Patients with chronic peripheral neuropathy suffer greatly and their quality of life is often restricted. Drug therapy can be accompanied by undesirable side effects and intolerances, or the hoped-for effect does not materialize. Therefore, in addition to drug therapy, attempts are also made to treat the physical symptoms with complementary procedures. In the case of severe forms, the search for a suitable form of therapy is difficult. Complex treatments can be an innovative way to treat peripheral neuropathy. At the same time, several different therapy methods are carried out at high frequency by a specialized treatment team. This study aimed to provide an overview of possible complementary forms of therapy. The focus was on a comparison of two interdisciplinary complex therapies that are used in severe cases in an acute inpatient care setting in Germany. The six dimensions (energy, sleep, pain, physicality, emotional response and social isolation) of the Nottingham Health Profile (NHP) were used to assess quality of life. Both complex treatments (naturopathic complex therapy/multimodal pain therapy) showed a significant reduction in impairment in all dimensions of the NHP. In addition, a multivariate analysis was carried out to take into account several influencing variables at the same time. At the time of admission to the hospital, the degree of chronicity was recorded for each patient. This allowed statements to be made about the effect of the respective therapy depending on the chronification stage of the patient. It has been shown that patients with acutely exacerbated pain with the highest degree of chronicity also benefit from both complex treatments. The naturopathic complex treatment gives the treatment team more options. Aspects such as nutrition, methods from phytotherapy and traditional Chinese medicine can be integrated into inpatient care. Thus, a patient-centered, holistic therapy can take place. However, an interdisciplinary holistic therapy requires more time for both the practitioner and the patient. This should be taken into account in the health systems in the context of the diagnosis related groups.

The role of diet and non-pharmacologic supplements in the treatment of chronic neuropathic pain: A systematic review

BACKGROUND/IMPORTANCE

Dietary interventions, vitamins, and nutritional supplementation are playing an increasingly important role in the management of neuropathic pain. Current pharmacological treatments are poorly tolerated and ineffective in many cases.

OBJECTIVE

This systematic review aims to study the efficacy of dietary interventions, vitamins, and nutritional supplementation in the management of chronic neuropathic pain in adults.

EVIDENCE REVIEW

The review followed PRISMA guidelines and was registered with PROSPERO (#CRD42022300312). Ten databases and gray literature, including Embase.com, MEDLINE and Web of Science, were systematically searched using a combination of keywords and controlled vocabulary related to chronic neuropathic pain and oral non-pharmacological supplements. Studies on adult humans published between 2000 and 2021 were considered for inclusion. The Cochrane Handbook was used to assess risk of bias, and Grading of Recommendations Assessment, Development, and Evaluation was used to determine overall quality of evidence.

FINDINGS

Forty studies were included in the final review, and results were categorized according to pain type including pain related to chemotherapy-induced peripheral neuropathy (CIPN, 22 studies, including 3 prospective cohorts), diabetic peripheral neuropathy (DPN, 13 studies, including 2 prospective), complex regional pain syndrome (CRPS-I, 3 studies, including 1 prospective), and other (2 studies, both RCT). The CIPN studies used various interventions including goshajinkigan (4 studies), vitamin E (5), vitamin B12 (3), glutamine (3), N-acetyl-cysteine (2), acetyl-l-carnitine (2), guilongtonluofang (1), ninjin'yoeito (1), alpha-lipoic acid (1), l-carnosine (1), magnesium and calcium (1), crocin (1), and antioxidants (1), with some studies involving multiple interventions. All CIPN studies involved varying cancers and/or chemotherapies, advising caution for generalizability of results. Interventions for DPN included alpha-lipoic acid (5 studies), vitamin B12 (3), acetyl-l-carnitine (3), vitamin E (1), vitamin D (2), and a low-fat plant-based diet (1). Vitamin C was studied to treat CRPS-I (3 studies, including 1 prospective). Magnesium (1) and St. John's wort (1) were studied for other or mixed neuropathologies.

CONCLUSIONS

Based on the review, we cannot recommend any supplement use for the management of CIPN, although further research into N-acetyl-cysteine, l-carnosine, crocin, and magnesium is warranted. Acetyl-l-carnitine was found to be likely ineffective or harmful. Alpha-lipoic acid was not found effective. Studies with goshajinkigan, vitamin B12, vitamin E, and glutamine had conflicting results regarding efficacy, with one goshajinkigan study finding it harmful. Guilongtonluofang, ninjin'yoeito, and antioxidants showed various degrees of potential effectiveness. Regarding DPN, our review supports the use of alpha-lipoic acid, acetyl-l-carnitine, and vitamin D. The early use of vitamin C prophylaxis for the development of CRPS-I also seems promising. Further research is warranted to confirm these findings.

Dietary and Nutritional Supplementation for Painful Diabetic Neuropathy: A Narrative Review

Painful diabetic neuropathy (PDN) is a serious and very common complication of diabetes mellitus (DM). It negatively affects the quality of life, increases morbidity and poses a financial burden on the health care system. Currently, treatment of PDN focuses on glycaemic control, while pathogenesis-oriented therapy has not yielded satisfactory results. The need to improve therapy remains. There is accumulating evidence on the potential benefit of nutritional interventions. This narrative review aims to examine the potential benefit of dietary and nutritional supplementation for PDN management. According to the preliminary research, supplementation with vitamin E, B-complex, omega-3 fatty acids, CoQ10 or N-acetylcysteine seems to be associated with promising results in improving PDN symptoms.

Vitamin D and diabetic peripheral neuropathy: A multi-centre nerve conduction study among Chinese patients with type 2 diabetes

AIMS

Increasing numbers of reports link vitamin D deficiency to diabetic peripheral neuropathy (DPN), yet evidence regarding neurological deficits and electromyogram is scarce. The present multi-centre study sought to investigate these associations based on objective quantifications.

MATERIALS AND METHODS

Information on DPN-related symptoms, signs, all diabetic microvascular complications, and nerve conduction abilities (quantified by nerve conduction amplitude and velocity, F-wave minimum latency (FML) of peripheral nerves) were collected from a derivation cohort of 1192 patients with type 2 diabetes (T2D). Correlation, regression analysis, and restricted cubic splines (RCS) were used to explore linear and non-linear relationships between vitamin D and DPN, which were validated in an external cohort of 223 patients.

RESULTS

Patients with DPN showed lower levels of vitamin D than those without DPN; patients with vitamin D deficiency (<30 nmol/L) tended to suffer more DPN-related neurological deficits (paraesthesia, prickling, abnormal temperature, ankle hyporeflexia, and distal pall hypoesthesia correlating with MNSI-exam score (Y = -0.005306X + 2.105, P = 0.048). Worse nerve conduction abilities (decreased motor nerve amplitude, sensory nerve amplitude, motor nerve velocity, and increased FML) were also observed in these patients. Vitamin D had a significant threshold association with DPN (adjusted OR = 4.136, P = 0.003; RCS P for non-linearity = 0.003) and correlates with other microvascular complications (diabetic retinopathy and diabetic nephropathy).

CONCLUSIONS

Vitamin D is associated with the conduction ability of peripheral nerves and may have a nerve- and threshold-selective relationship with the prevalence and severity of DPN among patients with T2D.

Nutraceuticals for Fibromyalgia and Neuropathic Pain

Both neuropathic pain and fibromyalgia are horrific painful conditions arising due to impairment in the somatosensory nervous system and the musculoskeletal system, respectively. They share some common symptoms like hyperalgesia, allodynia, insomnia, cognitive deficits, and mood disturbances. It is believed that fibromyalgia is the consequence of dysfunction of the central nervous system, autonomic nervous system, imbalance in neurotransmitters, and psychological and emotional stress. Henceforth, these pain syndromes have become a major challenge for healthcare professionals due to their complex etiology and poor availability and effectiveness of the drugs. Notably, the available synthetic drugs possess serious side effects including physical dependence and tolerance. Therefore, researchers are now seeking natural-based therapy for modulating chronic pain conditions. This chapter has been written with the intention of exploring the beneficial effects of various nutraceuticals including herbal dietary supplements in neuropathic pain and fibromyalgia.

Efficacy and safety of high-dose intramuscular vitamin D2 injection in type 2 diabetes mellitus with distal symmetric polyneuropathy combined with vitamin D insufficiency: study protocol for a multicenter, randomized, double-blinded, and placebo-controlled trial

Background

Distal symmetric polyneuropathy (DSPN) is the most common chronic complication of type 2 diabetes mellitus (T2DM). DSPN may lead to more serious complications, such as diabetic foot ulcer, amputation, and reduced life expectancy. Observational studies have suggested that vitamin D deficiency may be associated with the development of DSPN in T2DM. However, interventional studies have found that low-dose vitamin D supplementation does not significantly improve neuropathy in DSPN. This study aims to evaluate the efficacy and safety of intramuscular injection of high-dose vitamin D (HDVD) in T2DM with DSPN combined with vitamin D insufficiency.

Methods and analysis

We will conduct a multicenter, randomized, double-blinded, and placebo-controlled trial in four large hospitals. All eligible participants will be randomly assigned to either the vitamin D₂ supplement or placebo control group and injected intramuscularly monthly for 3 months. Additionally, anthropometric measurements and clinical data will be collected at baseline and 3 months. Adverse events will be collected at 1, 2, and 3 months. The primary outcome measure is the change in the mean Michigan Neuropathy Screening Instrument (MNSI) score at baseline and 3 months post-intervention. We will use the gold-standard liquid chromatography-tandem mass spectrometry method to distinguish between 25(OH)D₂ and 25(OH)D₃ levels. The MNSN score before the intervention will be used as a covariate to compare the changes between both groups before and after the intervention, and the analysis of covariance will be used to analyze the change in the MNSI score after HDVD supplementation.

Discussion

Glycemic control alone does not prevent the progression of DSPN in T2DM. Some studies have suggested that vitamin D may improve DSPN; however, the exact dose, method, and duration of vitamin D supplementation are unknown. Additionally, neuropathy repair requires HDVD supplementation to sustain adequate vitamin D levels. This once-a-month intramuscular method avoids daily medication; therefore, compliance is high. This study will be the first randomized controlled trial in China to analyze the efficacy and safety of HDVD supplementation for patients with T2DM and DSPN and will provide new ideas for pharmacological research and clinical treatment of diabetic neuropathy.

Clinical trial registration

https://www.chictr.org.cn/, identifier ChiCTR2200062266.

Painful Diabetic Peripheral Neuropathy: Practical Guidance and Challenges for Clinical Management

Painful diabetic peripheral neuropathy (PDPN) is present in nearly a quarter of people with diabetes. It is estimated to affect over 100 million people worldwide. PDPN is associated with impaired daily functioning, depression, sleep disturbance, financial instability, and a decreased quality of life. Despite its high prevalence and significant health burden, it remains an underdiagnosed and undertreated condition. PDPN is a complex pain phenomenon with the experience of pain associated with and exacerbated by poor sleep and low mood. A holistic approach to patient-centred care alongside the pharmacological therapy is required to maximise benefit. A key treatment challenge is managing patient expectation, as a good outcome from treatment is defined as a reduction in pain of 30-50%, with a complete pain-free outcome being rare. The future for the treatment of PDPN holds promise, despite a 20-year void in the licensing of new analgesic agents for neuropathic pain. There are over 50 new molecular entities reaching clinical development and several demonstrating benefit in early-stage clinical trials. We review the current approaches to its diagnosis, the tools, and questionnaires available to clinicians, international guidance on PDPN management, and existing pharmacological and non-pharmacological treatment options. We synthesise evidence and the guidance from the American Association of Clinical Endocrinology, American Academy of Neurology, American Diabetes Association, Diabetes Canada, German Diabetes Association, and the International Diabetes Federation into a practical guide to the treatment of PDPN and highlight the need for future research into mechanistic-based treatments in order to prioritise the development of personalised medicine.

The association between dietary micronutrient patterns and odds of diabetic nephropathy: A case-control study

Uncontrolled diabetes can lead to diabetic nephropathy (DN). The aim of the study was to investigate the relationship between different dietary micronutrient patterns and risk of DN in women. This was a case-control study. One hundred and five patients had DN (defined as urinary mg of albumin per gram of creatinine ≥30 mg/g) were chosen as the case and 105 women without DN were chosen as control. Dietary intakes were assessed by a semi-quantitative food frequency questionnaire. Principal component analysis with varimax rotation was used to derive the micronutrient patterns. Patterns were divided into two groups of lower and higher than median. Logistic regression was used to discern and find the odds ratio (ORs) of DN, and its 95% confidence interval (CI) based on the micronutrient patterns in crude and adjusted model. Three patterns which were included, (1) mineral patterns such as chromium, manganese, biotin, vitamin B6, phosphorus, magnesium, selenium, copper, zinc, potassium, and iron, (2) water-soluble vitamin patterns such as vitamin B5, B2, folate, B1, B3, B12, sodium and C, and (3) fat-soluble vitamin patterns such as calcium, vitamin K, beta carotene, alpha tocopherol, alpha carotene, vitamin E, and vitamin A, were extracted. An inverse relationship was found between risk of DN and following mineral patterns and fat-soluble vitamin patterns in adjusted model (ORs = 0.51 [95% CI 0.28-0.95], p = .03) and (ORs = 0.53 [95% CI 0.29-0.98], p = .04), respectively. No relationship was seen between water-soluble vitamin patterns and risk of DN in crude and adjusted model but the significance was decreased in adjusted model. The risk of DN was 47% decreased after high adherence of fat-soluble vitamin patterns. In addition, we saw a 49% decrease of risk of DN in high adherence group of mineral patterns. The findings confirm that renal-protective dietary patterns can reduce risk of DN.

A Scoping Review of Vitamin D for Nonskeletal Health: A Framework for Evidence-based Clinical Practice

BACKGROUND

Low serum 25-hydroxy-vitamin D [25(OH)D] levels are prevalent worldwide. Although the benefits of vitamin D supplementation have focused on skeletal disorders (eg, rickets, osteomalacia, osteoporosis), emerging evidence for nonskeletal health merits further discussion.

PURPOSE

The purpose of this review was to critically examine the vitamin D supplementation literature pertaining to nonskeletal health to help guide clinicians.

METHODS

A scoping review that included observational studies and randomized clinical trials (RCTs) was performed. Evidence from meta-analyses and individual RCTs are discussed, and controversies and future directions are considered.

FINDINGS

25(OH)D deficiency is a ubiquitous condition associated with multiple nonskeletal diseases, including cardiometabolic (heart disease, diabetes, and kidney disease), immune (HIV/AIDS and cancer), lung (from traditional chronic disorders to coronavirus disease 2019), and gut diseases. Vitamin D deficiency also affects health across the life span (children, pregnant, and elderly), mental illness, and reproduction in both men and women. In contrast, vitamin D supplementation does not necessarily improve major medical outcomes, even when low 25(OH)D levels are treated. Screening for 25(OH)D status remains an important practice, primarily for high-risk patients (eg, elderly, women with osteoporosis, people with low exposure to sunlight). It is reasonable to supplement with vitamin D to treat 25(OH)D deficiency, such that if beneficial nonskeletal health occurs, this may be considered as a coadjutant instead of the central tenet of the disease. Furthermore, optimizing dosing regimens is an important clinical consideration.

IMPLICATIONS

Although 25(OH)D deficiency is prevalent in nonskeletal diseases, there is no uniform evidence that vitamin D supplementation improves major medical outcomes, even when low 25(OH)D levels are corrected. Findings from RCTs warrant caution due to possible selection bias. Overall, vitamin D supplementation must be guided by circulating levels as a reasonable medical practice to correct 25(OH)D deficiency.

Causal association between vitamin D and diabetic neuropathy: a Mendelian randomization analysis

OBJECTIVES

Vitamin D has been linked to diabetic neuropathy (DN) in previous epidemiological observational studies, however, their findings are inconsistent. The causal relationship between vitamin D and DN remains unknown. In this study we aim to investigate the causal association of serum 25-hydroxyvitamin D (25OHD) and DN.

METHODS

Based on summary statistics from publicly available genome-wide association studies (GWAS) database, we detected the genetic correlation between serum 25OHD levels and DN by a two-sample Mendelian randomization (MR) analysis. The inverse-variance weighted (IVW) method was used as the primary analysis, weighted median and MR-Egger were applied as complementary methods for MR estimates. In addition, we took sensitivity analyses including Cochran's Q test, MR-Pleiotropy Residual Sum and Outlier (MR-PRESSO) and leave-one-out analysis to ensure that we obtained stable and reliable results.

RESULTS

Our MR study showed no significant genetic association between serum 25OHD levels and DN (OR = 1.13, 95% CI = 0.81-1.57, P = 0.46). Furthermore, in the reverse direction analysis, we did not find a significant causal effect of DN and serum 25OHD levels (OR = 0.99, 95% CI = 0.98-1.00, P = 0.09). Results of MR-Egger, Weighted Median were consistent with those of the IVW method. The sensitivity analysis suggesting that no significant heterogeneity and genetic pleiotropy was observed.

CONCLUSIONS

Our results provided no evidence to support the causal association of serum 25OHD levels with DN.

The association between micronutrient levels and diabetic foot ulcer: A systematic review with meta-analysis

BACKGROUND

Diabetic foot ulcers (DFU) are a major complication of diabetes mellitus (DM). Nutrient deficiencies are among the major risk factors in DFU development and healing. In this context, we aimed to investigate the possible association between micronutrient status and risk of DFU.

METHODS

A systematic review (Prospero registration: CRD42021259817) of articles, published in PubMed, Web of Science, Scopus, CINAHL Complete, and Embase, that measured the status of micronutrients in DFU patients was performed.

RESULTS

Thirty-seven studies were considered, of which thirty were included for meta-analysis. These studies reported levels of 11 micronutrients: vitamins B9, B12, C, D, E, calcium, magnesium, iron, selenium, copper, and zinc. DFU, compared to healthy controls (HC) had significantly lower vitamin D (MD: -10.82 14 ng/ml, 95% CI: -20.47, -1.16), magnesium (MD: -0.45 mg/dL, 95% CI: -0.78, -0.12) and selenium (MD: -0.33 µmol/L, 95% CI: -0.34, -0.32) levels. DFU, compared to DM patients without DFU, had significantly lower vitamin D (MD: -5.41 ng/ml, 95% CI: -8.06, -2.76), and magnesium (MD: -0.20 mg/dL, 95% CI: -0.25, -0.15) levels. The overall analysis showed lower levels of vitamin D [15.55ng/ml (95% CI:13.44, 17.65)], vitamin C [4.99µmol/L (95% CI:3.16, 6.83)], magnesium [1.53mg/dL (95% CI:1.28, 1.78)] and selenium [0.54µmol/L (95% CI:0.45, 0.64)].

CONCLUSION

This review provides evidence that micronutrient levels significantly differ in DFU patients, suggesting an association between micronutrient status and risk of DFU. Therefore, routine monitoring and supplementations are warranted in DFU patients. We suggest that personalized nutrition therapy may be considered in the DFU management guidelines.

SYSTEMATIC REVIEW REGISTRATION

https://www.crd.york.ac.uk/PROSPERO/display_record.php?RecordID=259817, identifier CRD42021259817.

Vitamin D in Neurological Diseases

Vitamin D may have multiple effects on the nervous system and its deficiency can represent a possible risk factor for the development of many neurological diseases. Recent studies are also trying to clarify the different effects of vitamin D supplementation over the course of progressive neurological diseases. In this narrative review, we summarise vitamin D chemistry, metabolism, mechanisms of action, and the recommended daily intake. The role of vitamin D on gene transcription and the immune response is also reviewed. Finally, we discuss the scientific evidence that links low 25-hydroxyvitamin D concentrations to the onset and progression of severe neurological diseases, such as multiple sclerosis, Parkinson's disease, Alzheimer's disease, migraine, diabetic neuropathy and amyotrophic lateral sclerosis. Completed and ongoing clinical trials on vitamin D supplementation in neurological diseases are listed.

Recent updates in the treatment of diabetic polyneuropathy

Distal symmetric diabetic peripheral polyneuropathy (DPN) is the most common form of neuropathy in the world, affecting 30 to 50% of diabetic individuals and resulting in significant morbidity and socioeconomic costs. This review summarizes updates in the diagnosis and management of DPN. Recently updated clinical criteria facilitate bedside diagnosis, and a number of new technologies are being explored for diagnostic confirmation in specific settings and for use as surrogate measures in clinical trials. Evolving literature indicates that distinct but overlapping mechanisms underlie neuropathy in type 1 versus type 2 diabetes, and there is a growing focus on the role of metabolic factors in the development and progression of DPN. Exercise-based lifestyle interventions have shown therapeutic promise. A variety of potential disease-modifying and symptomatic therapies are in development. Innovations in clinical trial design include the incorporation of detailed pain phenotyping and biomarkers for central sensitization.

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.

An Insight into Potential Pharmacotherapeutic Agents for Painful Diabetic Neuropathy

Diabetes is the 4th most common disease affecting the world's population. It is accompanied by many complications that deteriorate the quality of life. Painful diabetic neuropathy (PDN) is one of the debilitating consequences of diabetes that effects one-third of diabetic patients. Unfortunately, there is no internationally recommended drug that directly hinders the pathological mechanisms that result in painful diabetic neuropathy. Clinical studies have shown that anticonvulsant and antidepressant therapies have proven fruitful in management of pain associated with PDN. Currently, the FDA approved medications for painful diabetic neuropathies include duloxetine, pregabalin, tapentadol extended release, and capsaicin (for foot PDN only). The FDA has also approved the use of spinal cord stimulation system for the treatment of diabetic neuropathy pain. The drugs recommended by other regulatory bodies include gabapentin, amitriptyline, dextromethorphan, tramadol, venlafaxine, sodium valproate, and 5 % lidocaine patch. These drugs are only partially effective and have adverse effects associated with their use. Treating painful symptoms in diabetic patient can be frustrating not only for the patients but also for health care workers, so additional clinical trials for novel and conventional treatments are required to devise more effective treatment for PDN with minimal side effects. This review gives an insight on the pathways involved in the pathogenesis of PDN and the potential pharmacotherapeutic agents. This will be followed by an overview on the FDA-approved drugs for PDN and commercially available topical analgesic and their effects on painful diabetic neuropathies.

Practices of vitamin D supplementation leading to vitamin D toxicity: Experience from a Low-Middle Income Country

Introduction

The trend of prescribing VD preparations for nonspecific body aches and self-medication has increased significantly. The importance of vitamin D toxicity (VDT) has been underestimated and under recognized. This study was done to determine the frequency toxicity (>150 ng/ml) in subjects for 25-hydroxyvitamin D (25OHD) and evaluate the vitamin D (VD) supplements used by these subjects.

Methodology

This descriptive cross-sectional study was conducted at the Section of Chemical Pathology, Aga Khan University Hospital Karachi from April 2020 to March 2021. Subjects with 25OHD toxicity were contacted and information related to history of calcium and VD supplementation were collected. The statistical analysis was performed using the Microsoft Excel 2016.

Results

Over a year period 105398 subjects were tested for serum 25OHD, of which 0.34% (n = 364) subjects had 25OHD level of >150 ng/ml. After satisfying exclusion criteria 186 subjects (78 were <18 years of age and 108 were adults) were included in final analysis. All of these were using VD supplements and the main indications were delayed growth/short height (43.7%, n = 34) and aches or pains in (54.6%, n = 59) in pediatric and adult subjects respectively.

Most of the subjects were taking supplements orally (74.1%, n = 138). Commonly prescribed preparation in adults and pediatric was 200,000 IU (70.4%, n = 76) and 400 IU (35.9%, n = 28) respectively. Most subjects took supplements for 1–3 months (68.3%, n = 127). Stated total supplementation ranged from 20,000 IU to 3600,000 IU in pediatric subjects and 200,000 IU to 96,00,000 IU in adults.

Conclusions

Supplementation is a leading cause of potential toxic levels of 25OHD. The condition can be prevented by careful use of VD supplements and consistent monitoring.

•

Vitamin D toxicity is extremely rare; but it may happen at high doses. The use of vitamin D supplementation should be guarded and monitored.

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In this study we observed that vitamin D toxicity (>150 ng/ml) was prevalent, present in 0.34% (n=364) subjects.

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Main indications of supplementation were delayed growth in children and aches or pains in adults

The Benefits of Add-on Therapy of Vitamin D 5000 IU to the Vitamin D Levels and Symptoms in Diabetic Neuropathy Patients: A Randomized Clinical Trial

Background

Previous studies have demonstrated a significant relationship between vitamin D deficiency and the development of diabetic peripheral neuropathy (DPN). However, current studies are limited regarding the potential therapeutic benefits of vitamin D therapy in these patients.

Objective

This study aimed to assess the effect of oral vitamin D supplementation in patients with diabetic peripheral neuropathy in addition to standard treatment.

Methods

This study was a controlled, open-label, randomized clinical trial with an active comparator randomly allocated with a 1:1 ratio. The experimental group received an add-on oral vitamin D 5000 IU once daily and standard treatment (pregabalin, gabapentin, or amitriptyline) over eight weeks. The control group received standard treatment alone. The measured outcomes were the change in the score of the visual analog scale (VAS), numerical rating scale (NRS), and brief pain inventory (BPI). Vitamin D levels were also measured before and after the trial.

Results

Data from 68 subjects with DPN was collected and analyzed. Most of them (60.3%) were female, aged 64.96 ± 8.3 years. After eight weeks of treatment, the experimental group showed a more significant reduction of mean VAS (-3.34 ± 2.03 vs -2.37 ± 2.2, p=0.044) and burning pain (1.76 ± 7.16 vs 6.18 ± 13.93, p=0.046) scores compared to controls. Mood also improves better in the experimental group (88.2% vs 70.6%, p=0.031). At the end of the study, vitamin D levels were also improved more significantly in the experimental group (40.02 ± 15.33 ng/mL vs 18.73 ± 6.88 ng/mL; p<0.001) with greater changes from the baseline to week 8 (+24.14±13.68 ng/mL vs +3.10±4.20 ng/mL; p<0.001) compared to control group. The intervention group showed a negative correlation between vitamin D level and VAS score (r = -0.403, P = 0.018). There were no adverse events recorded in this study.

Conclusion

The addition of oral vitamin D 5000 IU to standard treatment significantly improves pain, mood, and vitamin D levels more effectively than standard treatment alone in patients with diabetic neuropathy.

Trial Registration

ClinicalTrials.gov.no NCT04689958.

Recent updates in the treatment of diabetic polyneuropathy

Distal symmetric diabetic peripheral polyneuropathy (DPN) is the most common form of neuropathy in the world, affecting 30 to 50% of diabetic individuals and resulting in significant morbidity and socioeconomic costs. This review summarizes updates in the diagnosis and management of DPN. Recently updated clinical criteria facilitate bedside diagnosis, and a number of new technologies are being explored for diagnostic confirmation in specific settings and for use as surrogate measures in clinical trials. Evolving literature indicates that distinct but overlapping mechanisms underlie neuropathy in type 1 versus type 2 diabetes, and there is a growing focus on the role of metabolic factors in the development and progression of DPN. Exercise-based lifestyle interventions have shown therapeutic promise. A variety of potential disease-modifying and symptomatic therapies are in development. Innovations in clinical trial design include the incorporation of detailed pain phenotyping and biomarkers for central sensitization.

The Treatment of Painful Diabetic Neuropathy

Painful diabetic peripheral neuropathy (painful-DPN) is a highly prevalent and disabling condition, affecting up to one-third of patients with diabetes. This condition can have a profound impact resulting in a poor quality of life, disruption of employment, impaired sleep, and poor mental health with an excess of depression and anxiety. The management of painful-DPN poses a great challenge. Unfortunately, currently there are no Food and Drug Administration (USA) approved disease-modifying treatments for diabetic peripheral neuropathy (DPN) as trials of putative pathogenetic treatments have failed at phase 3 clinical trial stage. Therefore, the focus of managing painful- DPN other than improving glycaemic control and cardiovascular risk factor modification is treating symptoms. The recommended treatments based on expert international consensus for painful- DPN have remained essentially unchanged for the last decade. Both the serotonin re-uptake inhibitor (SNRI) duloxetine and α2δ ligand pregabalin have the most robust evidence for treating painful-DPN. The weak opioids (e.g. tapentadol and tramadol, both of which have an SNRI effect), tricyclic antidepressants such as amitriptyline and α2δ ligand gabapentin are also widely recommended and prescribed agents. Opioids (except tramadol and tapentadol), should be prescribed with caution in view of the lack of definitive data surrounding efficacy, concerns surrounding addiction and adverse events. Recently, emerging therapies have gained local licenses, including the α2δ ligand mirogabalin (Japan) and the high dose 8% capsaicin patch (FDA and Europe). The management of refractory painful-DPN is difficult; specialist pain services may offer off-label therapies (e.g. botulinum toxin, intravenous lidocaine and spinal cord stimulation), although there is limited clinical trial evidence supporting their use. Additionally, despite combination therapy being commonly used clinically, there is little evidence supporting this practise. There is a need for further clinical trials to assess novel therapeutic agents, optimal combination therapy and existing agents to determine which are the most effective for the treatment of painful-DPN. This article reviews the evidence for the treatment of painful-DPN, including emerging treatment strategies such as novel compounds and stratification of patients according to individual characteristics (e.g. pain phenotype, neuroimaging and genotype) to improve treatment responses.

Role of vitamin D in diabetic retinopathy: Pathophysiological and clinical aspects

Epidemiological data predict a dramatic increase in the prevalence of diabetes and of diabetic retinopathy (DR) - the most common complication of diabetes-for which however we do not have so far effective tools for prevention and treatment. Since hypovitaminosis D is very frequent in patients with diabetes and vitamin D (VD) has vascular protective properties, several studies have addressed the association of VD deficiency with DR and its severity and progression, whereas the effects of VD supplementation on its natural history are largely unknown. Here we review the available evidence that supports the possible protective role of VD in DR and suggests to determine the VD levels in DR patients calling for a definitive randomized clinical trial to ascertain whether VD supplementation could protect against DR.

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

Background

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

Material/Methods

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

Results

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

Conclusions

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

The effects of vitamin D supplementation in carpal tunnel syndrome treatment outcomes: a systematic review

PURPOSE

Vitamin D deficiency is related to carpal tunnel syndrome symptoms. Correcting vitamin D levels by supplementation was supposed to improve carpel tunnel symptoms, though there is a lack of aggregated data about treatment outcomes. This study aimed to examine whether vitamin D supplementation could improve the treatment outcomes in carpal tunnel syndrome patients.

METHODS

A comprehensive search of the PubMed, Cochrane Library, Scopus, and Web of Science databases for articles on vitamin D and carpel tunnel syndrome from January 2000 to March 2021 was performed. The article screening and data extraction were performed by two investigators independently with blinding to decisions on selected studies. All included studies had assessed the quality of evidence using the Methodological Index for Non-Randomized Studies (MINORS) scoring system.

RESULTS

We retrieved four studies that met the eligibility criteria. The treatment outcomes were evaluated by visual analog scale (124 wrists), functional scores (176 patients), muscle strength (84 patients), and nerve conduction velocity (216 wrists). After vitamin D supplementation, two studies reported improved pain scores and nerve conduction velocity, and three studies showed enhancement of functional status.

CONCLUSION

Vitamin D administration could offer favorable outcomes in pain improvement, better functional status, and increased sensory conduction velocity in carpal tunnel syndrome. However, there is to date no recommendations concerning a standardized dose or duration of vitamin D administration in carpal tunnel syndrome; prescribing vitamin D at the usual appropriate dose is suggested as an additional treatment in patients with mild to moderate carpel tunnel symptoms.

LEVEL OF EVIDENCE

Level IV, therapeutic study.

The impact of vitamin D supplementation on peripheral neuropathy in a sample of Egyptian prediabetic individuals

Background: Vitamin D deficiency is seen more frequently in diabetic patients with distal symmetrical polyneuropathy. Unfortunately, there is a shortage of data concerning prediabetic individuals with peripheral neuropathy (PN). Therefore, we aimed to study the association of vitamin D deficiency with PN severity and to determine the effect of vitamin D supplementation on PN in prediabetics. Methods: A case-control study was conducted consisting of 89 prediabetic individuals with PN and a control group of prediabetics without PN, recruited from the outpatient department of the National Institute of Diabetes and Endocrinology, Cairo, Egypt. All patients were screened for PN using clinical examination and Douleur Neuropathique 4 diagnostic questionnaire (DN4). Group A (with PN) was assessed for neuropathic severity using the Short-Form McGill Pain Questionnaire (SF-MPQ). In addition, 25-hydroxyvitamin D, ionized calcium, phosphorus, parathyroid hormone (PTH), glycated hemoglobin (HbA1c), fasting blood glucose (FBG), 2-hour post 75g glucose (2h-PPBG) and lipid profile were measured for both groups. Prediabetic patients with PN were given vitamin D3 200.000 IU IM monthly for three months. After three months, clinical assessment, DN4, SF-MPQ and all laboratory measures were repeated. Results: Vitamin D was not associated with the severity of PN patients. However, supplementation of vitamin D resulted in a highly significant improvement in glycemic parameters , p≤0.001. Interestingly, neuropathy score and severity before vitamin D supplementation were (6.4±1.6 and 28.3±7.2) and after became (2.5±0.9 and 17±6.3, p≤0.001). Conclusion: Correction of vitamin D deficiency in prediabetics with PN as well as hypovitaminosis D, improves glycemic parameters, PN score and severity.

The impact of vitamin D supplementation on peripheral neuropathy in a sample of Egyptian prediabetic individuals

Background: Vitamin D deficiency is seen more frequently in diabetic patients with distal symmetrical polyneuropathy . Unfortunately, there is a shortage of data concerning prediabetic individuals with peripheral neuropathy (PN). Therefore, we aimed to study the association of vitamin D deficiency with PN severity and to determine the effect of vitamin D supplementation on PN in prediabetics. Methods: A case-control study was conducted consisting of 178 prediabetic individuals recruited from the outpatient department of the National Institute of Diabetes and Endocrinology, Cairo, Egypt. All patients were screened for PN using clinical examination and Douleur Neuropathique 4 diagnostic questionnaire (DN4). They were divided into 89 patients with and 89 patients without PN (group A and B). Group A was assessed for neuropathic severity using the Short-Form McGill Pain Questionnaire (SF-MPQ). In addition, 25-hydroxyvitamin D, ionized calcium, phosphorus, parathyroid hormone (PTH), glycated hemoglobin (HbA1c), fasting blood glucose (FBG), 2-hour post 75g glucose (2h-75g glucose) and lipid profile were measured. Prediabetic patients with PN were given vitamin D3 200.000 IU IM monthly for three months. After three months, clinical assessment, DN4, SF-MPQ and all laboratory measures were repeated. Results: Vitamin D level was negatively correlated with neuropathy score and severity (r = -0.65, -0.47, p <0.001) among group A. Moreover, vitamin D level was an independent predictor of neuropathic severity (odds ratio -0.18, 95% CI -0.33 -0.03, P ≤ 0.05). Supplementation of vitamin D resulted in a highly significant improvement in glycemic parameters and lipid profile, p ≤ 0.001. Interestingly, neuropathy score and severity before vitamin D supplementation were (6.4 ± 1.6 and 28.3 ± 7.2) and after became (2.5 ± 0.9 and 17 ± 6.3, p ≤ 0.001). Conclusion: Vitamin D deficiency is an independent risk factor for PN. Correction of vitamin D deficiency improves glycemic parameters, PN score and severity.

Protective Role of Vitamin D Therapy in Diabetes Mellitus Type II

Diabetes Mellitus type II (DM II) is a worldwide disease with a rapidly growing parallel prevalence and adversities affecting multi-body systems. Hence, it is imperative to treat DM II effectively, maintaining glucose homeostasis to avoid complications such as diabetic nephropathy, peripheral neuropathy, and retinopathy. Vitamin D, among many benefits, has positive outcomes on hemoglobin A1c (HbA1c) control. It aids in insulin secretion and sensitivity. We systematically screened four databases for relevant information; PubMed, Medline, PMC, and Google scholar. Inclusion and exclusion criteria were applied, and quality appraisal was then done using certain checklist tools: Newcastle-Ottawa tool, AMSTAR (A Measurement Tool to Assess Systematic Reviews) checklist, SANRA (Scale for the Assessment of Narrative Review Articles) checklist, and Cochrane bias assessment. Data were collected from 14 articles, of which eight are systematic reviews and meta-analysis, one is a narrative review, five are randomized controlled trials and three are general information about DM II and Vitamin D. In addition, this article evaluates the clinical significance of Vitamin D administration in DM II from a glucose homeostasis perspective, and complications such as nephropathy, neuropathy, and retinopathy. Vitamin D had a clinical positive impact on glucose level, particularly on hemoglobin A1c (HbA1c) reduction, alleviation of diabetic neuropathy and nephropathy symptoms, and hyperglycemia induced-oxidative stress on the retinal cells.

The increase of neuropathic symptoms in diabetic patients is related with osteopenia

PURPOSE

To investigate the relationship between the intensity of neuropathic pain and the severity of osteopenia in type 2 diabetic patients with painful diabetic peripheral neuropathy (painful DPN).

METHODS

In 220 patients with type 2 diabetes included in the screening, the presence of neuropathic pain was evaluated using the Douleur Neuropathique 4 Questions (DN4) scoring system. One hundred forty-five patients with painful DPN were identified and included in the study. Socio-demographic and laboratory evaluations were made and bone mineral density (BMD) of these patients was evaluated by the dual-energy x-ray absorptiometry (DEXA) method.

RESULTS

There was a significant correlation between the neuropathic pain score and the total T scores of the lumbar spine and femur in patients with painful DPN. According to the regression analysis (standard coefficients), the DN4 score (0.498); the level of vitamin D (- 0.246) and the female sex (0.236) for the lumbar spine region; age (0.387); DN4 score (0.261); and vitamin D level (- 0.155) for the femur region were independently influencing factors on the development of osteoporosis. When osteoporosis (T score ≤ - 2.5) of the lumbar spine was analyzed by binary logistic regression, the risk of osteoporosis in women was 4.4 times higher, and the risk increased with increasing DN4 score.

CONCLUSION

The increase of neuropathic symptoms in patients with DPN is an effective and important factor in the development of diabetic osteopenia.

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.

Is diabetic neuropathy associated with vitamin D status? A meta-analysis

Several studies have been conducted to investigate the relation between 25-hydroxyvitamin D [25(OH)D] level and diabetic neuropathy (DN). However, there is still no clear conclusion due to differences in study design and cut-off values used in the published work, in addition to the absence of a comprehensive meta-analysis (MA) on the topic. The present systematic review and MA therefore aims at clarifying the association between vitamin D level and peripheral DN in patients with type 2 diabetes mellitus. Primary research studies that explored the association between 25(OH)D level and diabetic peripheral neuropathy in type 2 diabetes were located from Medline, EMBASE, Web of Science, Cochrane Library, CINHAL and Google Scholar. Twenty-six studies met the inclusion criteria with 6277 participants where 2218 were diabetic with DN, 2959 were diabetic without DN and 406 were healthy. Diabetic patients with DN showed significantly lower serum 25(OH)D compared with patients without DN (standardised mean difference (SMD) of -0·92 (95 % CI -1·18, -0·65, I2 = 93·3 %, P < 0·0001). The pooled OR value of vitamin D deficiency was higher in patients with DN, 1·84 (95 % CI 1·46, 2·33, P < 0·0001) and 2·87 (95 % CI 1·10, 7·52, P = 0·03) when using fixed-effects and random-effects models, respectively. Vitamin D deficiency has been found to be highly prevalent among diabetic patients with neuropathy. Since 25(OH)D has been implicated in glucose haemostasis and showed benefit in reducing neuropathy symptoms, its supplementation is warranted for this population of patients.

Severe Vitamin D Deficiency Is Associated With Increased Expression of Inflammatory Cytokines in Painful Diabetic Peripheral Neuropathy

Background: The exact pathogenic mechanism of the painful diabetic peripheral neuropathy (DPN) is poorly understood. Our study aimed to evaluate the association amongst vitamin D status, inflammatory cytokines, and painful DPN. Methods: A total of 483 patients were divided into three groups, i.e., diabetes without DPN (no-DPN, n = 86), diabetes with painless DPN (painless DPN, n = 176) and diabetes with painful DPN (painful DPN, n = 221) groups. Basic information and laboratory results were collected. The concentrations of vitamin D (25-hydroxyvitamin D), high-sensitivity C-reactive protein, interleukin (IL)-2, IL-4, IL-6, IL-10, tumor necrosis factor-α (TNF-α), and interferon-γ (IFN-γ) were also measured. Results: The prevalence of severe vitamin D deficiency (<10 ng/mL) was more common in the painful DPN group than in the painless DPN and no-DPN groups (25.8,12.5, and 8.1%, respectively, P < 0.01). Cases in the painful DPN group had significantly higher concentrations of IL-6 (P < 0.01) and TNF-α (P < 0.01) than those in the two other groups. The multivariate logistic analysis showed that severe vitamin D deficiency, IL-6, and TNF-α were independent risks for painful DPN after adjusting for confounding factors. Furthermore, the vitamin D status had significantly negative correlations with IL-6 (r = -0.56, P < 0.01) and TNF-α (r = -0.47, P < 0.01) levels. Conclusion: Severe vitamin D deficiency was an independent risk factor for the painful DPN. Severe vitamin D deficiency status may play a role in the painful DPN pathogenesis through elevated IL-6 and TNF-α levels.

The synergistic effect of vitamin D supplement and mindfulness training on pain severity, pain-related disability and neuropathy-specific quality of life dimensions in painful diabetic neuropathy: a randomized clinical trial with placebo-controlled

Purpose

This study aimed to examine the synergistic effect of Vitamin D (VD) Supplement and mindfulness on neuropathic pain severity, Pain-Related Disability and Neuropathy-Specific Quality of Life (QOL) dimensions in painful diabetic neuropathy.

Methods

In this randomized controlled trial, 225 patients with painful diabetic neuropathy were randomly allocated to five groups: (1) mindfulness and placebo, (2) placebo, (3) mindfulness, (4) VD, and (5) mindfulness and VD. Mindfulness training includes twelve sessions, and VD patients received a daily four thousand IU oral dosage (four capsules) with 28,000 IU vitamin D weekly for 12 weeks. Laboratory analyses, Sun exposure time, Vitamin D intake, BMI and physical activity were measured in pre-test and post-test. Pain-Related Disability measured with The Pain Disability Index (PDI). For other outcome variables, Neuropathy, a Specific QOL questionnaire and Neuropathic pain severity scale were utilized. Data were analyzed using one-way repeated-measures analysis of variance (ANOVA), Scheffe Post-hoc test and paired sample t-test.

Results

In baseline, measures were not different among the groups. At the end-of-treatment, results showed improvement in all groups except the "placebo only" group for outcome variables. There was no difference between VD and mindfulness groups (within and not combined with placebo) in posttest. However, "VD + mindfulness" has a greater improvement rather than VD and mindfulness groups (P < 0.05). Moreover, both protocols have no significant effects on FBS, BMI and energy intakes (P > 0.05).

Conclusion

Combining VD and mindfulness can reduce pain severity and pain-related disability, so with these changes, patients experience improve in their quality of life.

Vitamin D deficiency is associated with painful diabetic neuropathy

BACKGROUND

The aetiology of painful diabetic neuropathy is unclear. We have evaluated vitamin D levels in diabetic patients with and without painful neuropathy.

METHODS

Forty-three patients with type 1 diabetes and painless (DPN) (n = 20) or painful (PDN) (n = 23) neuropathy and 14 non-diabetic healthy control subjects (C) underwent assessment of neurologic deficits, quantitative sensory testing (QST), electrophysiology, skin biopsy, corneal confocal microscopy (CCM) and measurement of serum 25(OH)D.

RESULTS

There were no significant differences for age, BMI, HbA_1c , lipids, neurological deficits, QST, electrophysiology, intra-epidermal nerve fibre density (IENFD) and corneal nerve morphology between patients with DPN and PDN. Both positive (hyperalgesia and allodynia) and negative symptoms (paraesthesia and numbness) of diabetic neuropathy were greater in PDN compared with DPN (P = .009 and P = .02, respectively). Serum 25(OH)D levels were significantly lower in PDN (24.0 ± 14.1 ng/mL) compared with DPN (34.6 ± 15.0 ng/mL, P = .01) and controls (34.1 ± 8.6 ng/mL, P = .03). The odds ratio in favour of painful diabetic neuropathy was 9.8 [P = .003 (95% CI, 2.2-76.4)] for vitamin D deficiency (<20 ng/mL) and 4.4 [P = .03 (95% CI, 1.1-19.8)] for vitamin D insufficiency (<30 ng/mL).

CONCLUSIONS

This study suggests that vitamin D deficiency and insufficiency are associated with painful diabetic neuropathy.

Vitamin D Supplementation in Diabetic Foot Ulcers: A Current Perspective

INTRODUCTION

Diabetic foot ulcer (DFU) is a major complication of diabetes mellitus, as it can physically and emotionally impact the person. Its management can be challenging and expensive, depending on the severity of the wound and the presence of infection.

BACKGROUND

The fat-soluble molecule, vitamin D, has gained great importance ever since its pleiotropism has been recognized. Its efficacy could be attributed to the presence of vitamin D receptors in most of the body tissues. Vitamin D plays a significant role in cell proliferation, differentiation, and immune modulation. It modulates the T and B cells resulting in the suppression of the immunoglobulins, autoimmunity, and inflammation.

METHODS

We performed a literature search with the objective to highlight the role of vitamin D in peripheral vascular disease and peripheral neuropathy, which are the major risk factors for DFU, as well as evidences of its role in wound healing and management of DFU.

RESULTS

Preclinical and clinical studies have shown that vitamin D influences multiple phases of wound healing and thereby accelerates the process. It modulates various cells involved in proliferation and remodelling phases. Vitamin D also enhances the expression of antimicrobial peptides that help to eliminate the microbes, as well as suppress the proinflammatory responses while enhancing the anti-inflammatory responses.

CONCLUSION

This review concludes vitamin D to have a protective role in the immune and vascular system, improve glycaemic outcomes, and wound healing. Therefore, vitamin D could be a preferred adjuvant in the management of DFU.

Perioperative Serum 25-Hydroxyvitamin D Levels as a Predictor of Postoperative Opioid Use and Opioid Use Disorder: a Cohort Study

IMPORTANCE

Vitamin D deficiency is associated with chronic pain syndromes and higher opioid use among cancer patients, but its association with opioid use among opioid-naïve subjects following a major surgical procedure with acute pain has not been explored.

OBJECTIVE

To determine the association between serum 25-hydroxyvitamin D (25(OH)D) levels, opioid use, and opioid use disorder.

METHODS

We identified commercially insured subjects aged 18-64 years with available perioperative serum 25-hydroxyvitamin D (25D) levels who underwent one of nine major surgical procedures in 2000-2014. Primary outcomes were dose and duration of opioid use measured using pharmacy claims. Secondary outcome was opioid use disorder captured using diagnosis codes. Multivariable negative binomial models with generalized estimating equations were performed examining the association between 25D levels and postoperative opioid use measures, adjusting for age, sex, race/ethnicity, Charlson score, education, income, latitude, and season of blood draw. Adjusted Cox regression was used to examine the association with opioid use disorder.

RESULTS

Among 5446 subjects, serum 25(OH)D was sufficient (≥ 20 ng/mL) among 4349 (79.9%) subjects, whereas 837 (15.4%) had insufficient (12 to < 20 ng/mL) and 260 (4.8%) had deficient (< 12 ng/mL) levels. On multivariable analysis, as compared with subjects with sufficient 25(OH)D levels, subjects with deficient 25(OH)D levels had 1.7 more days (95% CI 0.76, 2.58) of opioid use per year and had 98.7 higher morphine milligram equivalent dose (95% CI 55.7, 141.8) per year. Among 11,713 study cohort, subjects with deficient 25(OH)D levels were more likely to be diagnosed with opioid use disorders (HR 2.41; 95% CI 1.05, 5.52).

CONCLUSION

Patients undergoing common surgical procedures with deficient 25D levels are more likely to have higher opioid use and an increased risk of opioid use disorder compared to those with sufficient levels. Serum 25D levels may serve as a biomarker to identify subjects at increased risk of opioid misuse.

Diagnosing peripheral neuropathy in South-East Asia: A focus on diabetic neuropathy

Burning and stabbing pain in the feet and lower limbs can have a significant impact on the activities of daily living, including walking, climbing stairs and sleeping. Peripheral neuropathy in particular is often misdiagnosed or underdiagnosed because of a lack of awareness amongst both patients and physicians. Furthermore, crude screening tools, such as the 10-g monofilament, only detect advanced neuropathy and a normal test will lead to false reassurance of those with small fiber mediated painful neuropathy. The underestimation of peripheral neuropathy is highly prevalent in the South-East Asia region due to a lack of consensus guidance on routine screening and diagnostic pathways. Although neuropathy as a result of diabetes is the most common cause in the region, other causes due to infections (human immunodeficiency virus, hepatitis B or C virus), chronic inflammatory demyelinating polyneuropathy, drug-induced neuropathy (cancer chemotherapy, antiretrovirals and antituberculous drugs) and vitamin deficiencies (vitamin B1 , B6 , B12 , D) should be actively excluded.

State-of-the-art pharmacotherapy for diabetic neuropathy

INTRODUCTION

The global epidemic of diabetes has led to an epidemic of diabetes complications. Diabetic neuropathy is the most common microvascular complication, of which diabetic peripheral neuropathy (DPN) and autonomic neuropathy (AN) are the most prevalent, affecting ~50% of patients. DPN results in pain with a poor quality of life and a loss of sensation with an increased risk of foot ulceration. Autonomic neuropathy can cause significant morbidity in a minority and is associated with increased mortality. The cornerstone of treatment to prevent or limit the progression of DPN/AN is multifactorial risk factor modification including treatment of glycemia, lipids and blood pressure. Whilst, there are no FDA-approved disease-modifying therapies, there are a number of therapies to relieve symptoms in DPN and AN.

AREAS COVERED

The authors discuss current approved therapies for painful diabetic neuropathy and autonomic neuropathy. They also address the potential role of improving risk factors to limit the development and progression of diabetic neuropathy and new pathogenetic and pain-relieving treatments.

EXPERT OPINION

The FDA-approved Pregabalin and Duloxetine over 25 years ago and Tapentadol, 6 years ago for painful diabetic neuropathy. There are currently no FDA-approved disease-modifying treatments for diabetic neuropathy which has been attributed to inappropriate models of the disease with limited translational capacity and major limitations of trial designs and endpoints in clinical trials.

High-Dose Vitamin D Supplementation Improves Microcirculation and Reduces Inflammation in Diabetic Neuropathy Patients

We assessed the effect of different doses of vitamin D supplementation on microcirculation, signs and symptoms of peripheral neuropathy and inflammatory markers in patients with type 2 diabetes (T2DM). Sixty-seven patients with T2DM and peripheral neuropathy (34 females) were randomized into two treatment groups: Cholecalciferol 5000 IU and 40,000 IU once/week orally for 24 weeks. Severity of neuropathy (NSS, NDS scores, visual analogue scale), cutaneous microcirculation (MC) parameters and inflammatory markers (ILs, CRP, TNFα) were assessed before and after treatment. Vitamin D deficiency/insufficiency was detected in 78% of the 62 completed subjects. Following treatment with cholecalciferol 40,000 IU/week, a significant decrease in neuropathy severity (NSS, p = 0.001; NDS, p = 0.001; VAS, p = 0.001) and improvement of cutaneous MC were observed (p < 0.05). Also, we found a decrease in IL-6 level (2.5 pg/mL vs. 0.6 pg/mL, p < 0.001) and an increase in IL-10 level (2.5 pg/mL vs. 4.5 pg/mL, p < 0.001) after 24 weeks of vitamin D supplementation in this group. No changes were detected in the cholecalciferol 5000 IU/week group. High-dose cholecalciferol supplementation of 40,000 IU/week for 24 weeks was associated with improvement in clinical manifestation, cutaneous microcirculation and inflammatory markers in patients with T2DM and peripheral neuropathy.

The efficacy of vitamin D supplementation on painful diabetic neuropathy: Protocol for a systematic review and meta-analysis

BACKGROUND

Painful diabetic neuropathy (PDN) is one of the main and severe complications of diabetic patients, which not only accelerates the occurrence of ulcers of diabetic foot and amputation of lower extremities but also severely affects the quality of life. It is common that vitamin D deficiency in diabetic patients and especially in these patients diagnosed with diabetic peripheral neuropathy. Previous studies have proved that there is an apparent vitamin D deficiency in PDN patients, and vitamin D supplementation can effectively improve patients' pain symptoms and neurologic function. However, the evidence of these studies is unconvincing. Therefore, our research objective is to explore the effectiveness and security of vitamin D supplements on PDN.

METHODS

We will include randomized controlled trials on vitamin D supplementation in the treatment of PDN. And we will retrieve 8 electronic databases concerning this theme. The English databases mainly retrieve PubMed, Web of Science, Embase, and the Cochrane Library, while CNKI, VIP, CBM, and Wanfang database will be used to retrieve the Chinese Literature. There is no definite time limit for retrieval literatures, and the languages will be limited to Chinese and English. Besides, some clinical registration tests and gray literatures are also researched by us. The primary outcomes of our study are the amelioration of pain symptoms and assessment of peripheral nerve function. And some changes of biochemical indicators including fasting blood glucose, 2 hours postprandial blood glucose, glycosylated hemoglobin, calcium, and serum vitamin D level from preintervention and postintervention, adverse events will be regarded as secondary outcomes. The Review Manager RevMan5.3 will be used for meta-analysis of studies are included.

RESULTS

In this systematic review and meta-analysis, higher quality data evidence on vitamin D supplementation for PDN will be provided.

CONCLUSION

Our study will eventually provide a proof of the efficacy and safety of vitamin D supplementation in patients with PDN, and to add a new option for the prevention and treatment of PDN patients.

INPLASY REGISTRATION NUMBER

INPLASY202050065.

Vitamin D and Its Potential Interplay With Pain Signaling Pathways

About 50 million of the U.S. adult population suffer from chronic pain. It is a complex disease in its own right for which currently available analgesics have been deemed woefully inadequate since ~20% of the sufferers derive no benefit. Vitamin D, known for its role in calcium homeostasis and bone metabolism, is thought to be of clinical benefit in treating chronic pain without the side-effects of currently available analgesics. A strong correlation between hypovitaminosis D and incidence of bone pain is known. However, the potential underlying mechanisms by which vitamin D might exert its analgesic effects are poorly understood. In this review, we discuss pathways involved in pain sensing and processing primarily at the level of dorsal root ganglion (DRG) neurons and the potential interplay between vitamin D, its receptor (VDR) and known specific pain signaling pathways including nerve growth factor (NGF), glial-derived neurotrophic factor (GDNF), epidermal growth factor receptor (EGFR), and opioid receptors. We also discuss how vitamin D/VDR might influence immune cells and pain sensitization as well as review the increasingly important topic of vitamin D toxicity. Further in vitro and in vivo experimental studies will be required to study these potential interactions specifically in pain models. Such studies could highlight the potential usefulness of vitamin D either alone or in combination with existing analgesics to better treat chronic pain.

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

BACKGROUND & AIMS

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

METHODS

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

RESULTS

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

CONCLUSION

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