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

Differential seasonal performance of C3-epi-D3 level and proportion on multiple metabolic disorders in patients with type 2 diabetes mellitus

BACKGROUND AND AIM

Recent Mendelian randomization and meta analysis suggest a controversial causality between C3-epimer of 25 hydroxyvitamin D3 (C3-epi-D3) and type 2 diabetes mellitus (T2DM). The clinical evidence regarding the impact of C3-epi-D3 on the progression of T2DM is currently insufficient. This study aims to investigate whether C3-epi-D3 has any effect on metabolic disorders of T2DM patients.

METHODS

A total of 1222 patients with T2DM were prospectively enrolled in this study and followed up every 1 to 2 months for 3 to 6 months. Kidney biomarkers, lipids, electrolytes, and 25 hydroxyvitamin D (25-OHD) metabolites were measured as required during follow-up, to investigate the association of C3-epi-D3 levels and %C3-epi-D3 with metabolic disorders, including dyslipidemia, chronic kidney disease (CKD), and calcium-phosphorus metabolic disorder.

RESULTS

Among these T2DM patients, there were age and seasonal differences in C3-epi-D3 levels (χ2 = 10.419 and 19.609, P = 0.034 and < 0.001), but only seasonal difference in %C3-epi-D3 (χ2 = 79.299, P < 0.001). C3-epi-D3 levels showed an evident correlation with calcium-phosphorus product during autumn and winter (ρ = - 0.336 and - 0.304, both P < 0.001), and was confirmed as an independent factor on calcium-phosphorus metabolic disorder during autumn and winter by subsequent partial correlation analysis (rpartial = - 0.300 and - 0.319, both P < 0.001). Both C3-epi-D3 levels and %C3-epi-D3 showed evident correlation with the severity of chronic kidney disease (CKD) in summer (ρ = 0.344 and 0.445, both P < 0.001). But subsequent multinomial logistic regression confirmed that only %C3-epi-D3 independently associated with moderate CKD severity in summer (OR = 1.348, P < 0.001), as well as serious CKD severity in spring, summer, and autumn (OR = 1.324, 1.342, and 1.698, all P < 0.001). Additionally, no evident correlation was observed between C3-epi-D3 and dyslipidemia.

CONCLUSION

Our study releases a seasonally differential impact of C3-epi-D3 levels and proportions on metabolic disorders of T2DM patients, considering to be potentially related to their pathogenesis of different metabolic disorders. The independent association between %C3-epi-D3 and CKD suggests a potential pathological relevance involving C3-epi-D3 itself.

Vitamin D levels do not correlate with severity of idiopathic peripheral neuropathy

BACKGROUND AND AIMS

Peripheral neuropathy (PN) is a common neurological condition in elderly adults. Vitamin D deficiency has been associated with diabetic and chemotherapy-induced neuropathy, but its role in idiopathic PN, in which no underlying cause of neuropathy can be identified, has not been investigated.

METHODS

Two hundred thirty patients with idiopathic PN enrolled in the Peripheral Neuropathy Research Registry (PNRR) at Johns Hopkins University School of Medicine had vitamin D testing information on record. Linear and logistic regressions were used to investigate the relationship between absolute vitamin D level or vitamin D insufficiency (<20 ng/mL) and both the severity of neuropathy as measured by the reduced total neuropathy score (TNSr) and severity of neuropathic pain.

RESULTS

Sixteen (7%) patients were vitamin D insufficient (<20 ng/mL). Controlling for factors known to correlate with severity of neuropathy, there was no correlation between absolute vitamin D levels and TNSr (correlation coefficient 0.01, 95% CI -0.03 to 0.07, p = .59) and no association between vitamin D insufficiency and TNSr (correlation coefficient 0.3, 95% CI -2.8 to 3.4, p = .86). Vitamin D insufficiency was not associated with the presence of neuropathic pain (OR 4.1, 95% CI 0.6-26.0, p = .13), and there was no correlation between vitamin D levels and pain score (correlation coefficient 0.01, 95% CI -0.02 to 0.03, p = .59).

INTERPRETATION

In a single-center cohort of patients with idiopathic PN, there was no correlation between vitamin D levels and the severity of neuropathy or neuropathic pain.

Progression of diabetic nephropathy and vitamin D serum levels: A pooled analysis of 7722 patients

BACKGROUND AND AIM

Low serum Vitamin D levels have been associated with diabetic nephropathy (DN). Our study aimed to analyse the serum levels of vitamin D in patients suffering from DN and the subsequent changes in serum vitamin D levels as the disease progresses.

METHODS

PubMed, Embase, SCOPUS and Web of Science were searched using keywords such as '25 hydroxyvitamin D' and 'diabetic nephropathy'. We included observational studies that reported the association between the serum 25 hydroxy vitamin D levels and diabetic nephropathy without restriction to age, gender, and location. R Version 4.1.2 was used to perform the meta-analysis. The continuous outcomes were represented as mean difference (MD) and standard deviation (SD) and dichotomous outcomes as risk ratios (RR) with their 95% confidence interval (CI).

RESULTS

Twenty-three studies were included in our analysis with 7722 patients. Our analysis revealed that vitamin D was significantly lower in diabetic patients with nephropathy than those without nephropathy (MD: -4.32, 95% CI: 7.91-0.74, p-value = .0228). On comparing diabetic patients suffering from normoalbuminuria, microalbuminuria, or macroalbuminuria, we found a significant difference in serum vitamin D levels across different groups. Normoalbuminuria versus microalbuminuria showed a MD of -1.69 (95% CI: -2.28 to -1.10, p-value = .0002), while microalbuminuria versus macroalbuminuria showed a MD of (3.75, 95% CI: 1.43-6.06, p-value = .0058), proving that serum vitamin D levels keep declining as the disease progresses. Notwithstanding, we detected an insignificant association between Grade 4 and Grade 5 DN (MD: 2.29, 95% CI: -2.69-7.28, p-value = .1862).

CONCLUSION

Serum Vitamin D levels are lower among DN patients and keep declining as the disease progresses, suggesting its potential benefit as a prognostic marker. However, on reaching the macroalbuminuria stage (Grades 4 and 5), vitamin D is no longer a discriminating factor.

Vitamin D status and its association with inflammatory markers among Kurdish type 2 diabetic patients with painful diabetic peripheral neuropathy

Several clinical studies have shown an association between vitamin D deficiency and painful diabetic peripheral neuropathy (DPN). However, it is still unclear whether vitamin D status and inflammatory markers correlate in patients with painful DPN. In this context, we aimed to investigate the associations between serum vitamin D levels and inflammatory status in Kurdish type 2 diabetes patients (T2DM) with painful DPN and without painful DPN. A clinical case-control study was conducted on 86 Kurdish patients with T2DM. The patients were divided into two groups: the case group consisted of 45 patients with painful DPN and the control group consisted of 41 age- and sex-matched diabetics without DPN. In T2DM patients with and without painful DPN, the prevalence of severe vitamin D deficiency was observed in 46.67% and 21.95% of the patients, respectively (p = 0.0283). The mean serum 25(OH)-vitamin D level in patients with painful DPN (mean = 12.00, SD = 5.78) was significantly lower than in patients without DPN (mean = 16.36, SD = 7.86; p = 0.0041). Regression analysis revealed that vitamin D deficiency (p = 0.0120) and higher glycated hemoglobin (HbA1c) (p = 0.00003) were identified as predictive risk factors for painful DPN. However, there was no significant association between inflammatory status and vitamin D levels. The duration of sun exposure was the only controlling factor for vitamin D in painful DPN patients. In the Kurdish population, lower vitamin D and high HbA1c levels were predictive factors for painful 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.

Identifying health research in the era of COVID-19: A scoping review

Background

Health improvements are considered one of the most important fields of research. Since the coronavirus disease 2019 was declared a pandemic, it might have impacted clinical and public health research in various forms.

Objectives

The goal of this study is to explore health research approaches in the era of coronavirus disease 2019.

Methods

In this scoping review, we reviewed published medical full-text studies and identified potential areas of interest of health research in the era the coronavirus disease 2019 pandemic during the last 3 years within a higher educational setting. A bibliometric analysis was used to compare among published works.

Results

Among the 93 studies that met the inclusion criteria, most focused on mental health (n = 23; 24.7%). Twenty-one publications targeted coronavirus disease 2019 and its consequences on general health. Other studies have described hemato-oncological, cardiovascular, respiratory, and endocrinological diseases. 42 studies were cross-sectional or cohort studies and most of them published in Q1 journals. Almost half of them belonged to the Faculty of Medicine (49.5%) followed by the School of Arts, Sciences, and Psychology (26.9%).

Conclusions

Health research has been demonstrated to be important, at all times, especially during crises. Therefore, researchers need to invest more efforts into seeking new medical updates in various health-related fields, regardless of their correlation with coronavirus disease 2019.

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.

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.

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

CONTEXT

Diabetic peripheral neuropathy (DPN) is a common complication.

OBJECTIVE

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

DATA SOURCES

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

DATA EXTRACTION

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

DATA ANALYSIS

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

CONCLUSION

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

Vitamin D Deficiency in Patients with Diabetes in French Guiana: Epidemiology and Relation with Microvascular and Macrovascular Complications

Vitamin D (VD) insufficiency is common among patients with diabetes in French Guiana. The study aimed to evaluate the prevalence of VD deficiency in the different type of diabetes encountered and to analyze the relationship between VD deficiency and diabetes complications. Methods: An observational study was conducted between May 2019 and May 2020 in French Guiana, based on data from the CODIAM study (Diabetes Cohort in French Amazonia), describing the characteristics of patients with diabetes mellitus. Among 600 patients enrolled with diabetes, 361 had an available VD assay. Results: The mean 25(OH)VD (hydroxycalciferol) level was 27.9 ng/mL. The level of VD was inversely proportional to the HbA1c (glycated hemoglobin) level. Patients with angina pectoris had a greater proportion of deficiencies VD < 20 ng/mL than those without angina. By contrast, patients with retinopathy had higher vitamin D concentrations than those without retinopathy. There was no association between vitamin D and arteriopathy, stroke, nephropathy and polyneuropathy. VD deficiency was more frequent in women, and in patients with a high school education. Conclusion: The prevalence of VD deficiency was high in patients with diabetes in French Guiana, emphasizing the importance of VD supplementation.