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

The correlation between serum vitamin D status and the occurrence of diabetic foot ulcers: a comprehensive systematic review and meta-analysis

The association between vitamin D concentrations and the occurrence of diabetic foot ulcers (DFUs) remains a topic of ongoing debate. In order to provide a comprehensive and updated review, we conducted this meta-analysis to further investigate the relationship between vitamin D concentrations and DFUs occurrence. The following databases, including Cochrane Library, EMBASE, Web of Science, PubMed, CBM, CNKI, WANFANG DATA and VIP Database, were systematically searched for studies published up to Dec. 20th, 2023. The combined estimation was calculated using both fixed-effects and random-effects models. The overall effect size was reported as a weighted mean difference (WMD) with a corresponding 95% confidence interval (95%CI). Data analysis was performed utilizing Review Manager 5.4 and Stata 14. The Protocol has been registered in PROSPERO CRD42024503468. This updated meta-analysis, incorporating thirty-six studies encompassing 11,298 individuals with or without DFUs, demonstrated a significant association between vitamin D deficiency/insufficiency and an elevated risk of DFUs occurrence (< 25 nmol/L, OR 3.28, P < 0.00001; < 50 nmol/L, OR 2.25, P < 0.00001; < 75 nmol/L, OR 1.67, P = 0.0003). Vitamin D concentrations were significantly lower in individuals with DFUs compared to those without DFUs (P < 0.00001). Subgroup analyses consistently demonstrated this trend among the older population (> 50 years, P < 0.00001), individuals with long duration of diabetes (> 10 years, P < 0.00001), and those with poor glycemic control (mean HbA1c 8%-9% and > 9%, P < 0.00001).

Advancing the Diagnosis of Diabetic Neuropathies: Electrodiagnostic and Skin Autofluorescence Methods

INTRODUCTION

Diabetic neuropathy (DN) is a generic term for various neuropathies coexisting in a single patient. Clinical diagnosis alone can be misleading, yet routine electrodiagnostic studies in diabetes care are rare. Skin autofluorescence (SAF) is a recognized DN risk factor with potential screening value. This article highlights the diagnostic challenges and raises awareness of the often underdiagnosed neuropathic conditions in diabetes patients.

MATERIAL AND METHODS

We present common entrapment neuropathy cases from our diabetes clinic's electrodiagnosis laboratory in Iași, Romania. We selected seven type 2 diabetes patients with sensory or sensory-motor distal polyneuropathy and atypical DN presentations investigated through electroneurography (ENG) and electromyography (EMG) with the Neurosoft® EMG instrument and SAF measured by standard procedures. Subsequently, a narrative literature review was conducted.

RESULTS

Entrapment neuropathies were diagnosed in all the patients: three carpal tunnel syndromes, two ulnar neuropathies (one proximal, one distal), one peroneal neuropathy, and one case of meralgia paresthetica. The lower-limb cases showed radiculoplexopathy, and there was one case of superficial radial nerve neuropathy. The SAF values ranged from 2.5 AU to 3.4 AU.

CONCLUSIONS

Electrodiagnosis is essential for detecting focal neuropathies in patients with sensory-motor distal polyneuropathy. Elevated SAF levels may correlate with symptom severity, although further research, including large cohorts, is needed.

Research trends in the relationship between vitamin D and type 2 diabetes mellitus: a 20-year bibliometric and visualization analysis

Introduction

Vitamin D has a significant correlation with type 2 diabetes. Insufficient levels of vitamin D can cause insulin resistance, which impairs the ability of cells to respond to insulin and worsens the progression of diseases. Furthermore, vitamin D has the potential to enhance the release of insulin, enhance the regulation of blood sugar levels, and reduce the glycemic index. Research has indicated that insufficient levels of vitamin D may elevate the likelihood of experiencing complications related to type 2 diabetes, including cardiovascular disease and neuropathy. This study employed bibliometric analysis to investigate recent advancements in research about the relationship between vitamin D and type 2 diabetes.

Methods

We searched for articles on the topic of vitamin D and type 2 diabetes published between January 1, 2004, and December 31, 2023. The search was performed on February 20, 2024, using the Web of Science Core Collection (WoSCC). Utilizing VOSviewer and CiteSpace, we conducted bibliometric analysis and visualization.

Results

A comprehensive study was conducted on a total of 1362 papers pertaining to the relationship between vitamin D and type 2 diabetes. The United States had the biggest number of publications and the highest effect among these articles. Within the top 10 most published journals, the journal "DIABETES CARE" has the highest H-index, indicating its significant influence in this field of study. Currently, there is an extensive body of research on the supplementation of vitamin D for the improvement of type 2 diabetes and prevention of complications in type 2 diabetes, as well as its related mechanisms. Research related to bone turnover and peripheral neuropathy represents a promising area for future studies.

Conclusion

Overall, bibliometrics may assist researchers in comprehending the trajectory, significant themes, and scholarly influence of the field concerning vitamin D and type 2 diabetes. This, in turn, offers substantial backing for future studies that delve further into the subject matter.

Vitamin D and major chronic diseases

Numerous observational studies have demonstrated a significant inverse association between vitamin D status and the risk of major chronic disease, including type 2 diabetes (T2D), cardiovascular disease (CVD), and cancer. However, findings from Mendelian randomization (MR) studies and randomized controlled trials (RCTs) suggest minimal or no benefit of increased vitamin D levels. We provide an overview of recent literature linking vitamin D to major chronic diseases. Because emerging evidence indicates a potential threshold effect of vitamin D, future well-designed studies focused on diverse populations with vitamin D deficiency or insufficiency are warranted for a more comprehensive understanding of the effect of maintaining sufficient vitamin D status on the prevention of major chronic diseases.

The impact of vitamin D on the etiopathogenesis and the progression of type 1 and type 2 diabetes in children and adults

Diabetes is a common chronic metabolic disease with complex causes and pathogenesis. As an immunomodulator, vitamin D has recently become a research hotspot in the occurrence and development of diabetes and its complications. Many studies have shown that vitamin D can reduce the occurrence of diabetes and delay the progression of diabetes complications, and vitamin D can reduce oxidative stress, inhibit iron apoptosis, promote Ca2+ influx, promote insulin secretion, and reduce insulin resistance. Therefore, the prevention and correction of vitamin D deficiency is very necessary for diabetic patients, but further research is needed to confirm what serum levels of vitamin D3 are maintained in the body. This article provides a brief review of the relationship between vitamin D and diabetes, including its acute and chronic complications.

Association of vitamin D deficiency and subclinical diabetic peripheral neuropathy in type 2 diabetes patients

Background

Diabetic peripheral neuropathy (DPN) contributes to disability and imposes heavy burdens, while subclinical DPN is lack of attention so far. We aimed to investigate the relationship between vitamin D and distinct subtypes of subclinical DPN in type 2 diabetes (T2DM) patients.

Methods

This cross-sectional study included 3629 T2DM inpatients who undertook nerve conduction study to detect subclinical DPN in Zhongshan Hospital between March 2012 and December 2019. Vitamin D deficiency was defined as serum 25-hydroxyvitamin D (25(OH)D) level < 50 nmol/L.

Results

1620 (44.6%) patients had subclinical DPN and they were further divided into subgroups: distal symmetric polyneuropathy (DSPN) (n=685), mononeuropathy (n=679) and radiculopathy (n=256). Compared with non-DPN, DPN group had significantly lower level of 25(OH)D (P < 0.05). In DPN subtypes, only DSPN patients had significantly lower levels of 25(OH)D (36.18 ± 19.47 vs. 41.03 ± 18.47 nmol/L, P < 0.001) and higher proportion of vitamin D deficiency (78.54% vs. 72.18%, P < 0.001) than non-DPN. Vitamin D deficiency was associated with the increased prevalence of subclinical DPN [odds ratio (OR) 1.276, 95% confidence interval (CI) 1.086-1.501, P = 0.003] and DSPN [OR 1. 646, 95% CI 1.31-2.078, P < 0.001], independent of sex, age, weight, blood pressure, glycosylated hemoglobin, T2DM duration, calcium, phosphorus, parathyroid hormone, lipids and renal function. The association between vitamin D deficiency and mononeuropathy or radiculopathy was not statistically significant. A negative linear association was observed between 25(OH)D and subclinical DSPN. Vitamin D deficiency maintained its significant association with subclinical DSPN in all age groups.

Conclusions

Vitamin D deficiency was independently associated with subclinical DSPN, rather than other DPN subtypes.

Vitamin D deficiency increases the risk of diabetic peripheral neuropathy in elderly type 2 diabetes mellitus patients by predominantly increasing large-fiber lesions

AIMS

This study explores the link between Vitamin D deficiency (VDD) and diabetic peripheral neuropathy (DPN) in elderly type 2 diabetes mellitus (T2DM) patients.

METHODS

Involving 257 elderly T2DM patients, the study utilized propensity score matching to balance age, sex, and diabetes duration. VDD was defined as serum 25-hydroxyvitamin D [25(OH)D] levels below 20 ng/ml. Large nerve fiber lesions were evaluated by electromyogram, while small nerve fiber lesions were assessed by measuring skin conductance.

RESULTS

DPN patients had notably lower serum 25(OH)D levels than non-DPN patients [15.05 vs. 18.4 ng/ml, P = 0.018]. VDD was identified as an independent risk factor for DPN (odds ratio = 2.488, P = 0.008) in multivariate logistic regression analysis. Spearman's correlation showed negative correlations between serum 25(OH)D levels and specific nerve latencies, and positive correlations with specific nerve velocities and amplitudes. The VDD group exhibited longer median sensory nerve latencies and motor evoked potential latencies compared to the vitamin D-sufficient group. Further, VDD is associated with the prolongation of the median motor nerve latency (odds ratio = 1.362, P = 0.038).

CONCLUSIONS

VDD is independently associated with a higher risk of DPN. VDD may promote the development of DPN by affecting large nerve fibers.

Vitamin D Deficiency Participates in Depression of Patients with Diabetic Peripheral Neuropathy by Regulating the Expression of Pro-Inflammatory Cytokines

Objective

Vitamin D deficiency is associated with patients with diabetic peripheral neuropathy (DPN), and low levels of vitamin D are common in patients with depression. Depression is common in DPN patients and the definite pathogenesis remains unclear. This study aimed to determine vitamin D deficiency in the onset of depression in DPN and evaluate the effect of vitamin D supplementation on depression.

Methods

A total of 192 patients with DPN were enrolled in this study. Clinical and laboratory information was collected. Chemiluminescent immunoassay was used to measure the level of 25(OH)D. Enzyme-linked immunosorbent assay was employed to measure the concentrations of interleukin (IL)-1β, tumor necrosis factor-α (TNF-α), and IL-17A. Subjects with low 25(OH)D received 5000IU vitamin D daily for 12 weeks. Depression scores and levels of 25(OH)D, IL-1β, TNF-α, and IL-17A were re-evaluated after supplementation.

Results

The incidence of vitamin D deficiency and depression was high in DPN patients. Compared with vitamin D sufficient participants, Hamilton Depression Rating Scale (HAMD) scores and the levels of inflammatory markers IL-1β, TNF-α, and IL-17A were significantly higher in insufficient group (all p<0.05). HAMD score, IL-1β, TNF-α, and IL-17A were negatively correlated with 25(OH)D (all p<0.05). A linear relationship existed among IL-1β, TNF-α, IL-17A, and 25(OH)D (p<0.05). HAMD scores, IL-1β, TNF-α, and IL-17A were all reduced significantly after supplementation of vitamin D (p<0.05). Binary logistic analysis revealed that vitamin D insufficiency was an independent risk factor for depression in patients with DPN. Receiver operating characteristic (ROC) curve analysis showed a high sensitivity (87.20%) of 25(OH)D in discriminating DPN patients with depression.

Conclusion

Vitamin D deficiency participated in occurrence of depression in DPN patients and could be mediated, at least in part, by upregulation of pro-inflammatory cytokines. Vitamin D supplementation may be effective in improving depressive symptoms in DPN patients.

Glucagon-like peptide-1 receptor agonists for the management of diabetic peripheral neuropathy

Diabetes mellitus is a prevalent chronic disease characterized by hyperglycemia. Diabetic peripheral neuropathy (DPN) is one of the complications of diabetes mellitus and is caused by neuron injury induced by hyperglycemic circumstances. The incidence of DPN varies among different countries and regions, ranging from nearly 20% to over 70%. Patients with DPN may encounter symmetric pain or discomfort of the extremes, leading to reduced quality of life and even amputation. The pharmacological management for painful DPN mainly includes antidepressants due to their analgesic effects. Nevertheless, effective therapies to impact the pathogenesis and progression of DPN are lacking. Glucagon-like peptide-1 receptor (GLP-1R) agonists show efficacy in controlling blood glucose and serve as a treatment modality for diabetes mellitus. In recent years, evidence has been proposed that GLP-1R agonists exert neuroprotective effects through modulating inflammation, oxidative stress, and mitochondrial dysfunction. On the other hand, clinical evidence on the potential of GLP-1R agonists for treating DPN is still controversial and limited. This narrative review summarizes the preclinical and clinical studies investigating the capacity of GLP-1R agonists as therapeutic agents for DPN.

Vitamins in neuropathy: pathophysiological and therapeutic roles

PURPOSE OF REVIEW

Vitamin deficiency is a risk factor in the development of peripheral neuropathy, which leads to complex and severe diseases. This review provides an update overview of the literature on the roles of vitamins in peripheral neuropathy, highlighting their pathophysiological and therapeutic roles.

RECENT FINDINGS

The importance and clinical manifestations and implications of the vitamins and vitamin deficiencies are further demonstrated in peripheral neuropathy and the associated diseases. Vitamin deficiency is common in various severe and complex diseases such as diabetes, chemotherapy, acute nutritional axonal neuropathy, dermatitis, complex regional pain syndrome, postherpetic neuralgia, carpal tunnel syndrome, and so forth and some rare clinical case reports. There is evidence that deficiencies of almost all vitamins are associated with diabetic neuropathy. Vitamin supplementation may serve as an effective therapeutic strategy.

SUMMARY

The vitamins play critical roles in maintaining physiological functions, and vitamin deficiencies cause peripheral neuropathy with various severe and complex diseases. The therapeutic benefits of vitamins and further understanding of the mechanisms for vitamin treatment effects should be emphasized and highlighted. More clinical trials are needed to establish optimal treatment strategies for vitamins in the various neuropathies. A large range of people/patients screening for vitamin deficiencies may be considered in order to provide early diagnosis and timely medical assistance.