Albuminuria Reduction after High Dose of Vitamin D in Patients with Type 1 Diabetes Mellitus: A Pilot Study

The association between vitamin D and the progression of diabetic nephropathy: insights into potential mechanisms

Aims

Vitamin D deficiency (VDD) is prevalent in the population, with inadequate intake, impaired absorption and metabolism as the main causative factors. VDD increases the risk of developing chronic diseases such as type 2 diabetes mellitus (T2DM) and diabetic nephropathy (DN), but the molecular mechanisms underlying this phenomenon are not known. The aim of this study was to investigate the association and potential mechanisms of vitamin D levels with the progression of DN by analyzing general clinical data and using bioinformatics methods.

Methods

The study included 567 diabetes mellitus type 2 (T2DM) patients from the Rocket Force Characteristic Medical Center as the case group and 221 healthy examinees as the normal control group. T2DM patients were categorized into T2DM, early diabetic nephropathy (EDN), and advanced diabetic nephropathy (ADN) based on the progression of diabetic nephropathy. The renal RNA-seq and scRNA-seq data of patients with DN were mined from public databases, and the differential expression of vitamin D-related genes in normal-EDN-ADN was analyzed by bioinformatics method, protein interaction network was constructed, immune infiltration was evaluated, single cell map was drawn, and potential mechanisms of VD and DN interaction were explored.

Results

Chi-square test showed that vitamin D level was significantly negatively correlated with DN progression (p < 0.001). Bioinformatics showed that the expression of vitamin D-related cytochrome P450 family genes was down-regulated, and TLR4 and other related inflammatory genes were abnormally up-regulated with the progression of DN. Vitamin D metabolism disturbance up-regulate "Nf-Kappa B signaling pathway," B cell receptor signaling pathway and other immune regulation and insulin resistance related pathways, and inhibit a variety of metabolic pathways. In addition, vitamin D metabolism disturbance are strongly associated with the development of diabetic cardiomyopathy and several neurological disease complications.

Conclusion

VDD or vitamin D metabolism disturbance is positively associated with the severity of renal injury. The mechanisms may involve abnormal regulation of the immune system by vitamin D metabolism disturbance, metabolic suppression, upregulation of insulin resistance and inflammatory signalling pathways.

High dose cholecalciferol supplementation causing morning blood pressure reduction in patients with type 1 diabetes mellitus and cardiovascular autonomic neuropathy

We evaluated the association of cardiovascular autonomic neuropathy (CAN), blood pressure (BP) and Vitamin D (VD) levels before and after high-dose cholecalciferol supplementation (4000/10,000) UI/day) for 12 weeks in patients (N = 67) with type 1 diabetes mellitus (T1DM). Based on this prospective controlled pilot study, patients were divided into group 1 (N = 23 with CAN) and group 2 (N = 44 without CAN). At baseline, group 1 had higher systolic BP (SBP) during sleep (115 ± 14 vs. 107 ± 12 mmHg, p = 0.04) and lower nocturnal dipping (3 ± 5 vs. 8 ± 6%, p = 0.009). Among those with loss of nocturnal dipping, 45.4% (20/44) had CAN, while in normal nocturnal dipping group it occurred only in 13% (3/23) (p = 0.007). Non-dipper group had worse CAN parameters when compared to dipper group [Very low frequency (VLF) (2.5 ± 0.5vs.2.8 ± 0.4 s, p = 0.01), total power (TP) (2.9 ± 0.6 vs. 3.3 ± 0.4 s, p = 0.01), Valsalva coefficient (1.5 ± 0.4 vs. 1.8 ± 0.6, p = 0.06)]. After VD, only group 1 improved CAN parameters [TP (2.5 ± 0.4 vs. 2.8 ± 0.6, p = 0.01) and VLF (2.2 ± 0.4 vs. 2.4 ± 0.5, p = 0.03). Group 1 presented a reduction in morning SBP (120 ± 20 vs. 114 ± 17 mmHg, p = 0.038) and in morning SBP surge (13 ± 13 vs. 5 ± 14, p = 0.04). High-dose VD was associated with improved CAN parameters and reduced awake SBP and morning SBP surge. These findings suggest that VD may benefit patients with cardiovascular autonomic neuropathy. ISRCTN32601947, registration date: 31/07/2017.

Prospective effects of cholecalciferol supplementation on irisin levels in sedentary postmenopausal women: A pilot study

Introduction

In postmenopausal women, vitamin D deficiency has been associated with disability, low muscle mass and fractures. Irisin is an important myokine that may contribute to the maintenance of muscle and bone density. Vitamin D is associated with the growth and function of muscle tissue through interactions between the vitamin D receptor and PGC-1α and activation of p38/MAPK (mitogen-activated protein kinase) in muscle, a mechanism similar to irisin action. The aim of this pilot study was to evaluate the effects of cholecalciferol supplementation on serum irisin levels in sedentary postmenopausal women with hypovitaminosis D (25(OH)D < 20 ng/mL).

Material and methods

80 sedentary postmenopausal women with hypovitaminosis D and low sun exposure were supplemented with cholecalciferol (30,000 IU/month) for 12 months. Calcium, parathyroid hormone, alkaline phosphatase (AP) and irisin levels were measured before and after supplementation.

Results

25(OH) vitamin D increased in all participants. Serum levels of irisin increased (from 0.52 ± 0.27 to 0.80 ± 0.53; p < 0.003), accompanied by a decrease in AP (from 80 ± 24 to 66 ± 23; p < 0.001).

Conclusions

Restoration of vitamin D status increased serum irisin levels in sedentary postmenopausal women. Whether increased serum irisin levels may have an impact on clinical outcomes deserves further evaluation.

Association between serum 25- hydroxyvitamin D and albuminuiria in middle-aged and older Chinese patients with type 2 diabetes

OBJECTIVE

The objective was to analyze the relationship between serum 25-hydroxy-vitamin D (25(OH)D) level and albuminuiria in middle-aged and older patients with type 2 diabetes of Gansu Province.

METHODS

Data pertaining to 380 in-patients with type 2 diabetes were collected. Subjects were classified groups based on gender,age,25(OH)D,BMI and UACR.Serum 25(OH)D and other clinical characteristics among various UACR groups were compared.The relationship between albuminuiria and 25(OH)D was analyzed.

RESULTS

Out of the 380 subjects, 83.4%were classified as vitamin D deficiency, 14.5%were classified as vitamin D insufficiency, while 2.1% were classified as vitamin D sufficiency. Among the participants,41% had albuminuria (microalbuminuria,28.7%;macroalbuminuria,12.3%).The prevalence of 25(OH)D deficiency in the albuminuria group(84.6%) was significantly higher than that in the normoalbuminuria group(82.6%)(Mann-Whitney U test:Z = -3.86,P = 0.000); patients with macroalbuminuria had the highest prevalence of 25(OH)D deficiency (91.5%; P < 0.01 versus normoalbuminuria).A binary logistic analysis demonstrated that 25(OH)D were protective factors for albuminuria.

CONCLUSIONS

The prevalence of vitamin D deficiency in patients with albuminuria was overtly higher than that in patients without albuminuria among middle-aged and older adults with type 2 diabetes.

Association between Vitamin D Status and Mortality among Adults with Diabetic Kidney Disease

OBJECTIVE

Emerging evidence demonstrates that vitamin D status contributes to the incidence of diabetic kidney disease (DKD). However, the causal relationships between vitamin D and mortality among individuals with DKD are inconclusive. Our study is aimed at exploring the relationship between serum 25-hydroxyvitamin D (25(OH)D) concentrations and mortality among adults with DKD. Research Design and Methods. Our study included 1,202 adult participants with DKD from the National Health and Nutrition Examination Survey (NHANES) 2001-2014. Cox and competing-risks regression were used to estimate hazard ratios (HRs) and 95% CIs for associations between 25(OH)D concentrations and survival.

RESULTS

The overall mean serum 25(OH)D concentration was 55.9 ± 26.3. Vitamin D deficiency (25(OH)D < 50 nmol/l), insufficiency group (50 ≤ 25(OH)D < 75 nmol/l), and sufficiency group (25(OH)D ≥ 75 nmol/l) were observed in 552 (45.9%), 409 (34.0%), and 241 (20.0%) participants, respectively. Higher levels of vitamin D were significantly associated with improved all-cause and nonaccident- and malignant neoplasm-cause mortality among individuals with DKD after adjusting for the potential confounding factors.

CONCLUSIONS

We observed widespread vitamin D deficiency or insufficiency in DKD patients. Higher 25(OH)D values were significantly correlated with lower risk of mortality after adjusting for confounding variables.

Enhanced renoprotective actions of Paricalcitol and omega-3 fatty acids co-therapy against diabetic nephropathy in rat

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Pcal and ω-3 monotherapies moderately attenuated hyperglycaemia and dyslipidaemia.

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Pcal and ω-3 monotherapies equally reduced renal oxidative stress and inflammation.

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Pcal/ω-3 co-therapy showed enhanced anti-diabetic and renoprotection effects.

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Co-therapy may induce boosted metabolic, anti-oxidative & anti-inflammatory actions.

Introduction

Although the synthetic vitamin D analogue, Paricalcitol, and omega-3 Fatty acids (ω-3) alleviated diabetic nephropathy (DN), their combination was not previously explored.

Objectives

This study measured the potential ameliorative effects of single and dual therapies of Paricalcitol and/or ω-3 against DN.

Methods

Forty rats were assigned as follow: negative (NC) and positive (PC) controls, Paricalcitol, ω-3 and Paricalcitol + ω-3 groups. Diabetes was generated by high-fat/high-fructose diet and a single streptozotocin injection (40 mg/kg). DN was confirmed by raised fasting blood glucose (FBG), polyuria, proteinuria, and decreased urine creatinine levels. Paricalcitol intraperitoneal injections (0.25 µg/Kg/day; 5 times/week) and oral ω-3 (415 mg/kg/day; 5 times/week) started at week-9 and for eight weeks.

Results

The PC group showed hyperglycaemia, dyslipidaemia, abnormal renal biochemical parameters, elevated caspase-3 expression, and increased apoptosis by TUNEL technique. The mRNAs and proteins of the pathogenic molecules (TGF-β1/iNOS) and markers of tissue damage (NGAL/KIM-1) augmented substantially in the PC renal tissues relative to the NC group. The oxidative stress (MDA/H₂O₂/protein carbonyl groups) and pro-inflammatory (IL1β/IL6/TNF-α) markers increased, whereas the anti-inflammatory (IL10) and anti-oxidative (GSH/GPx1/GR/SOD1/CAT) declined, in the PC renal tissues. The monotherapy groups were associated with ameliorated FBG, lipid profile and renal functions, and diminished TGF-β1/iNOS/NGAL/KIM-1/Caspase-3 alongside the apoptotic index than the PC group. The oxidative stress and pro-inflammatory markers decreased, whilst the anti-oxidative and anti-inflammatory molecules escalated, in the monotherapy groups than the PC group. Although the Paricalcitol renoprotective actions were better than ω-3, all the biomarkers were abnormal than the NC group. Alternatively, the Paricalcitol + ω-3 protocol exhibited the best improvements in metabolic control, renal functions, oxidative stress, inflammation, and apoptosis. However, FBG and tissue damage were persistently higher in the co-therapy group than controls.

Conclusions

Both monotherapies showed modest efficacy against DN, whereas their combination displayed boosted renoprotection, possibly by enhancing renal anti-oxidant and anti-inflammatory pathways.

Health-related quality of life in T1DM patients after high-dose cholecalciferol supplementation: data from a pilot clinical trial

BACKGROUND

Type 1 Diabetes Mellitus (T1DM) impacts health-related quality of life (HRQoL). Cross-sectional studies suggest that low levels of vitamin D (VD) may impair HRQoL, however, the effect of VD supplementation on quality of life in T1DM patients has not yet been clarified. Our study evaluated the effects of high-dose VD supplementation on HRQoL in T1DM.

METHODS

We performed a prospective study with 64 patients receiving cholecalciferol (4000 IU/day for patients with 25-OH-vitamin D [25(OH)D] between 30 and 60 ng/mL, and 10,000 IU/day for those with 25(OH)D below 30 ng/mL) for 12 weeks, as part of a research protocol. HRQoL was assessed with EuroQol instruments (EQ-5D and EQ-VAS).

RESULTS

There was an improvement in global EQ-5D index, and analysing specifically the EQ-5D domains, we observed an improvement in mobility (1.3 ± 0.6 versus 1.1 ± 0.3, p < 0.01). Evaluating possible outcome influencing variables, we detected a reduction in albuminuria at the end of the trial, without changes in BMI, lipids, blood pressure, glycemic control and insulin doses. We found correlations between final albuminuria and the dimensions: mobility (r = 0.6; p < 0.01), personal care (r = 0.7; p < 0.01), pain and discomfort (r = 0.6; p < 0.01) and habitual activities (r = 0.6; p < 0.01), suggesting an association between albuminuria reduction and the impact of VD supplementation on HRQoL.

CONCLUSION

Our data showed that high doses of cholecalciferol supplementation can improve HRQoL in patients with T1DM, and the reduction of albuminuria seems to be an important factor in this context.

TRIAL REGISTRATION

(ISRCTN32601947), 03/06/2017 retrospectively registered.

Correlation Between Serum 25-Hydroxyvitamin D Levels in Albuminuria Progression of Diabetic Kidney Disease and Underlying Mechanisms By Bioinformatics Analysis

AIM

This study aimed to assess the correlation between serum concentration of 25-hydroxyvitamin D and albuminuria progression of diabetic kidney disease (DKD) and to use bioinformatics methods to determine the potential mechanism in the pathological process of advanced DKD.

METHODS

A total of 178 type 1 diabetes mellitus (T1DM) patients with microalbuminuria complications who were hospitalized at least twice (with an interval > 24 months) in the Department of Endocrinology of The First Affiliated Hospital of USTC were included in this study. According to the urinary albumin creatinine ratio (UACR), we classified DKD stages as follows: microalbuminuria (UACR, 30-300 mg/g), and macroalbuminuria (UACR, >300 mg/g). We divided the patients into DKD progression (N=44) and stable group (N=134) on account of urinary albumin-to-creatinine ratio (UACR) by at least two randomized measurements. Stable group was defined as UACR between 30 and 300 mg/g, whereas progression group was defined as UACR >300 mg/g at the end of follow-up. Data were obtained from participants' medical records, and the 25-hydroxyvitamin D level was categorized into three groups as follows: G1 (N=45), <10 ng/mL; G2 (N=80), 10-20 ng/ml; and G3 (N=53), ≥20 ng/mL. The Nephroseq database (http://v5.nephroseq.org) was used to identify VDR expression in diabetic nephropathy. The dataset GSE142025 from GEO (http://www.ncbi.nlm.nih.gov/geo) was downloaded. After stratification by the median-centered log2 VDR expression value, the 21 advanced DKD samples were divided into two groups (low VDR expression group and high VDR expression group). Gene set enrichment analysis (GSEA) (http://software.broadinstitute.org/gsea/index.jsp). Differentially expressed genes (DEGs) were screened by the limma package (adjusted p < 0.05, |logFC| > 1). The Gene Ontology (GO; http://www.geneontology.org/) database and pathway analysis within the Kyoto Encyclopedia of Genes and Genomes (KEGG; https://www.kegg.jp/) were performed using the R package ClusterProfile. The CIBERSORT (Cell type Identification By Estimating Relative Subsets Of known RNA Transcripts) algorithm was utilized for calculating the infiltrated immune cells in advanced kidney tissues.

RESULTS

1) A multivariate Cox regression analysis revealed that DR (diabetic retinopathy), eGFR (estimated glomerular filtration rate), and 25-hydroxyvitamin D were significant independent predictors of DKD progression (HR: 2.57, 95% CI: 1.44.4.24, p=0.007; HR: 2.13, 95% CI: 1.58.3.79, p = 0.011; HR: 0.732, 95% CI: 0.232-0.816, p = 0.023, respectively). 2) Kaplan-Meier survival curves of DKD progression by serum 25-hydroxyvitamin D stratification showed that the G2 and G3 groups were significantly different when compared with the G1 group (log-rank χ2 = 14.69, p <0.001; χ2 = 28.26, p <0.001, respectively). 3) There was a weak negative correlation between 25-hydroxyvitamin D level and UACR at baseline,and the overall mean rate of change in eGFR was 1.121 ± 0.19 ml/min/1.73 m2/year. Neither crude nor adjusted rate of decline in eGFR was significantly different among patients classified according to baseline serum 25-hydroxyvitamin D levels (all p<0.05). 4) The high expression of VDR group was most positively correlated with enriched gene sets like reactome innate immune system and reactome G alpha I signaling events when compared with the low expression of VDR group. 5) The CIBERSORT algorithm showed decreased M2 macrophage infiltration in advanced kidneys in comparison to low VDR expression and high VDR expression.

CONCLUSION

This study concluded that low 25-hydroxyvitamin D levels can predict an increased risk of DKD albuminuria progression and eGFR decline. Decreased M2 macrophage infiltration may be a potential mechanism involved in this pathogenesis.

High-dose Vitamin D Supplementation on Type 1 Diabetes Mellitus Patients: Is there an Improvement in Glycemic Control?

BACKGROUND

Some authors evaluated the effect of VD on hyperglycemia in T1DM, but the results remain controversial. This study aims to analyze the effects of high-dose VD supplementation on T1DM patients' glycemic levels, maintaining stable doses of insulin.

METHODS

Prospective, 12-week clinical trial including 67 T1DM patients, supplemented with high doses of cholecalciferol according to participants' VD value. Patients with VD levels below 30 ng/mL received 10,000 IU/day; those with levels between 30-60 ng/mL received 4,000 IU/day. Patients who had not achieved 25(OH)D levels > 30 ng/ml or presented insulin dose variation during the study were not analyzed.

RESULTS

Only 46 out of 67 patients accomplished the criteria at the end of the study. There was no general improvement in the glycemic control evaluated by HbA1c (9.4 ± 2.4 vs 9.4 ± 2.6, p=NS) after VD supplementation. However, a post-hoc analysis, based on HbA1c variation, identified patients who had HbA1c reduced at least 0.6% (group 1, N = 13 (28%)). In addition, a correlation between 25(OH)D levels with HbA1c and total insulin dose at the end of the study was observed (r = -0.3, p<0.05; r=-0.4, p<0.05, respectively), and a regression model demonstrated that 25(OH)D was independent of BMI, duration of T1DM and final total insulin dose, being capable of determining 9.2% of HbA1c final levels (Unstandardized B coefficient = -0.033 (CI 95%: -0.064 to -0.002), r2 = 0.1, p <0.05).

CONCLUSION

Our data suggest that VD is not widely recommended for glycemic control. Nevertheless, specific patients might benefit from this approach.

Vitamin D Analogs Can Retard the Onset or Progression of Diabetic Kidney Disease: A Systematic Review

Introduction

Previous studies have shown that vitamin D analogs (such as paricalcitol) can reduce albuminuria in patients with diabetes mellitus and retard the progression of diabetic kidney disease (DKD). A recent systematic review reported significant improvement of renal function in patients with DKD who received vitamin D or its analogs. Study-driven data about their use in improving DKD outcomes have continued to accumulate over the years.

Aim

This paper aims to systematically review the contemporary evidence about the effectiveness of vitamin D analogs in retarding the onset or progression of DKD.

Methods

With appropriate descriptors, two electronic databases (PubMed and Google Scholar) were searched for articles published between 2015 and 2021 in the English language. Primary studies that fulfilled the inclusion criteria were selected; their titles and abstracts were screened, and duplicates were removed. Relevant data were retrieved from the final selected studies using a preconceived data-extraction form.

Results

A total of eight studies (three randomized-controlled trials, one prospective study, and four cross-sectional studies) were reviewed. A total of 6,243 participants were investigated in the eight studies and comprised young adults, middle-aged adults, and the elderly with a male-gender predominance. One randomized controlled trial reported that paricalcitol significantly improved renal function in type 1 diabetes patients with renal impairment when combined with renin-angiotensin-aldosterone system (RAAS) blockers. A strong correlation between vitamin D deficiency and DKD risk was noted in the majority of the cross-sectional studies. High doses of cholecalciferol (4,000 or 10,000 IU/day), given early in DKD, significantly reduced disease prevalence.

Conclusion

Paricalcitol may retard the onset or progression of DKD, especially if administered in combination with RAAS blockers. The association of vitamin D deficiency with DKD risk also supports this therapeutic effect. Future systematic reviews are still needed to strengthen the current evidence on therapeutic benefit of vitamin D or its analogs in DKD.

Health implication of vitamin D on the cardiovascular and the renal system

Vitamin D regulates the calcium and phosphorus balance in the body. The activated form of vitamin D (1 α,25-dihydroxyvitamin D) binds to vitamin D receptor which regulates genes that control cell proliferation, differentiation and apoptosis. In the cardiovascular system, the vitamin D receptor is present in cardiomyocytes and the arterial wall. A clear correlation between vitamin D level and cardiovascular diseases is established. Vitamin D deficiency affects the renin-angiotensin system leading to ventricular hypertrophy and eventually to stroke. While clinical trials highlighted the positive effects of vitamin D supplements on cardiovascular disease these still need to be confirmed. This review outlines the association between vitamin D and cardiovascular and renal disease summarising the experimental data of selective cardiovascular disorders.

Association Between 25(OH)Vitamin D, HbA1c and Albuminuria in Diabetes Mellitus: Data From a Population-Based Study (VIDAMAZON)

BACKGROUND

The effect of glycemic control on diabetic kidney disease (DKD) is well known. Recent evidence has suggested that Vitamin D (VD) may have a nephroprotective effect in diabetes, but the relationship between VD, glycemic control, and albuminuria has yet to be clarified.

OBJECTIVE

Evaluate the relationship between 25-hydroxy-vitamin D [25(OH)D], HbA1c, and albuminuria in Diabetes Mellitus (DM).

PATIENTS AND METHODS

Cross-sectional study with 1576 individuals with DM who had 25(OH)D, HbA1c, and albuminuria levels measured. Patients with abnormal creatinine levels were excluded, in order to avoid interference on VD levels by impaired kidney function.

RESULTS

Patients with HbA1c ≥7% had lower 25(OH)D when compared to patients with HbA1c <7% (29.7 ± 10.2 vs 28.1 ± 9.9 ng/ml, p = 0.003) and 25(OH)D levels seems to predict 1.5% of HbA1c behavior. The 25(OH)D concentrations in patients with normoalbuminuria were higher than the levels observed in those with micro or macroalbuminuria (29.8 ± 9.0 vs 26.8 ± 8.6 and 25.1 ± 7.6, respectively, p = 0.001), patients who had 25(OH)D <20 ng/ml and 25(OH)D <30 ng/ml were at a higher risk of presenting albuminuria [OR = 2.8 (95% CI = 1.6 - 4.9), p<0.001, and OR = 2.1 (95% CI = 1.3 - 4.6), p<0.001, respectively]. In our regression model, albuminuria was influenced by HbA1c (r² = 0.076, p<0.00001) and 25(OH)D (r² = 0.018, p = 0.002) independently.

CONCLUSION

Our study found an association between vitamin D levels, HbA1c and DKD. Additionally, our data suggest that the association between urinary albumin excretion and vitamin D levels is independent of glycemic control in patients with diabetes. Even though our patients presented normal creatinine levels, it is necessary further prospective studies to confirm if this association precedes or not the loss of renal function.

High-dose Cholecalciferol Supplementation Reducing Morning Blood Pressure in Normotensive DM1 Patients

BACKGROUND

Vitamin D (VD) deficiency has been related to several endocrine metabolic and cardiovascular diseases. The effect of VD supplementation on blood pressure (BP) in patients with diabetes is controversial.

OBJECTIVE

The aim of this study was to evaluate high-dose vitamin D supplementation effects on blood pressure of normotensive patients with diabetes mellitus 1 (DM1) patients by 24-hour ambulatory blood pressure monitoring (ABPM).

METHODS

We performed a clinical trial including 35 DM1 normotensive patients, who received doses of 4,000 or 10,000 IU/day of cholecalciferol for 12 weeks according to previous VD levels. They underwent 24-hour ABPM, along with glycated hemoglobin, creatine, lipids profile and PCRus dosage before and after VD supplementation.

RESULTS

We found an expressive reduction of systolic and diastolic morning blood pressures (117±14 vs 112±14, p<0,05; 74±9 vs 70±10 mmHg, p<0,05, respectively) with no changes in other pressoric markers. Besides, we noticed a relationship between levels of VD after supplementation and diastolic morning blood pressure (r= -0,4; p<0.05).

CONCLUSION

Our study suggests an association between supplementation of high doses of vitamin D and the reduction of morning blood pressure in normotensive DM1 patients.

Vitamin D Deficiency as a Predictor of a High Prevalence of Coronary Artery Disease in Pancreas Transplant Candidates With Type 1 Diabetes

INTRODUCTION

Pancreas transplantation is a high-risk procedure in terms of cardiovascular complications. Therefore, identification of all cardiovascular risk factors is crucial to prevent cardiovascular complications after pancreas transplantation. Vitamin D deficiency (VDD) appears to be a potential risk factor for coronary artery disease.

OBJECTIVE

To determine the prevalence of VDD in pancreas transplant candidates, and further to examine the relationship between vitamin D and the prevalence of coronary artery disease and lipid profile parameters.

MATERIALS AND METHODS

This is a prospective cross-sectional study. We enrolled consecutive patients with type 1 diabetes eligible for simultaneous pancreas-kidney transplantation or pancreas transplant alone. The laboratory tests included HbA1c, lipid profile, creatinine, and total 25-hydroxyvitamin D (25(OH)D). The diagnosis of coronary artery disease was based on coronary angiography.

RESULTS

The study population included 48 patients. VDD was revealed in 48% of patients and coronary artery disease in 35% of patients. The mean concentration of vitamin D in the entire cohort was 21.3 ± 9.48 ng/ml. The median value of 25(OH)D in patients with coronary artery disease was significantly lower than in patients without coronary artery disease (18.5 (11.6-21.5) vs. 24.8 (18.4-31.8) ng/ml, p = 0.018). There was a significant relationship between VDD and coronary artery disease (OR = 4.36; 95% confidence interval (CI): 1.22-15.64, p = 0.034). A patient's odds of having coronary artery disease while having a sufficient level of vitamin D was 4.36 times lower than if the patient had VDD. There was a significant relationship between VDD and hypertension (OR = 5.91; 95% CI: 1.12-31.20, p = 0.039) and hemodialysis (OR = 4.25; 95% CI: 1.25-14.5, p = 0.023). There was no significant correlation between 25(OH)D and lipid profile.

CONCLUSIONS

VDD is highly prevalent in pancreas transplant candidates with type 1 diabetes. There is a significant relationship between VDD and increased prevalence of coronary disease. The lack of any significant association between serum vitamin D and lipid profile suggests that the relationship between vitamin D and coronary artery disease results from other causes.

The Emerging Role of Vitamin D and Vitamin D Receptor in Diabetic Nephropathy

Diabetic nephropathy (DN), one of the most common and severe microvascular complications of diabetes mellitus (DM), is an important risk factor for DM patient's death. Nowadays, DN has become the leading cause of end-stage renal disease (ESRD) in most countries without effective therapeutic methods. Recently, the renoprotective effects mediated by vitamin D (VD) and vitamin D receptor (VDR) have been evidenced. VD, a kind of steroid with the active form 1,25(OH)₂D₃, has been known for the crucial roles in the modulation of serum calcium and phosphorus concentrations. It exerts important functions by binding with its receptor VDR.VDR, a transcription factor located at chromosome 12 containing 9 exons, is one of the nonsteroid nuclear hormone receptor superfamily, which participates in transcriptional regulation of genes in tissue- and cell-specific ways. Increasing evidences have demonstrated that VD/VDR signaling pathway possesses a variety of kidney-protective effects in DN patients, such as antiproteinuria, antifibrosis, anti-inflammatory, and preventing podocyte damage. Although there are many studies on the role of the VD/VDR signaling pathway in DN, the effects and mechanisms still need to be further explained. This review summarized the multiple roles of VD/VDR in podocyte injury, tubule lesions, interstitial fibrosis, and inflammation, as well as the clinical applications about DN to explore much more and effective therapeutic methods for DN.

Improvement in Cardiovascular Autonomic Neuropathy After High-Dose Vitamin D Supplementation in Patients With Type 1 Diabetes

BACKGROUND

Cardiovascular autonomic neuropathy (CAN) is associated with diabetes mellitus, increasing morbidity and mortality. Some cross-sectional studies associated CAN with low 25-hydroxyvitamin D levels. The aim of our study was to evaluate the effect of high-dose vitamin D (VD) supplementation on CAN in Type 1 Diabetes Mellitus (T1DM) patients.

METHODS

We performed a prospective study with 23 patients diagnosed with T1DM and CAN. Subjects with VD levels <30 ng/ml received 10,000 IU/day; the ones with VD levels between 30-60 ng/ml were given 4,000 IU/day for 12 weeks.

RESULTS

There was an improvement in CAN parameters related to resting heart rate variability, such as time domain parameters [Maximum RR interval (0.77 ± 0.11 vs 0.94 ± 0.51 s, p <0.05), Mean length of regular RR intervals (0.71 ± 0.10 vs 0.76 ± 0.09 s, p <0.05) and Standard deviation of all NN intervals (0.02 ± 0.01 vs 0.03 ± 0.02 s; p <0.01)] and frequency domain parameters [Low Frequency (1.9 ± 0.5 vs 2.5 ± 0.9 s, p < 0.001), Total Power (2.5 ± 0.4 vs 2.8 ± 0.6 s, p <0.05)]. In addition, there was a correlation between absolute VD level variation and posttreatment High Frequency (%), as well as among percent variation in VD level and end-of-study Low Frequency/High Frequency ratio (r=0.6, p<0.01; r= -0.5, p<0.05, respectively).

CONCLUSION

Our pilot study is the first to suggest a strong association between high-dose vitamin D supplementation and improved cardiovascular autonomic neuropathy in T1DM patients. It occurred without any variation in HbA1C, blood pressure levels, lipids, and insulin dose.

CLINICAL TRIAL REGISTRATION

http://www.isrctn.com/ISRCTN32601947, identifier ISRCTN32601947.

Vitamin D protects against diabetic nephropathy: Evidence-based effectiveness and mechanism

Vitamin D has been suggested to harbor multiple biological activities, among them the potential of vitamin D in the protection of diabetic nephropathy (DN) has attracted special attention. Both animal studies and clinical trials have documented an inverse correlation between low vitamin D levels and DN risk, and supplementation with vitamin D or its active derivatives has been demonstrated to improve endothelial cell injury, reduce proteinuria, attenuate renal fibrosis, and resultantly retard DN progression. Vitamin D exerts its pharmacological effects primarily via vitamin D receptor, whose activation inhibits the renin-angiotensin system, a key culprit for DN under hyperglycemia. The anti-DN benefit of vitamin D can be enhanced when administrated in combination with angiotensin converting enzyme inhibitors or angiotensin II receptor blockers. Mechanistic studies reveal that pathways relevant to inflammation participate in the pathogenesis of DN, however, consumption of vitamin D-related products negatively regulates inflammatory response at multiple levels, indicated by inhibiting macrophage infiltration, nuclear factor-kappa B (NF-κB) activation, and production of such inflammatory mediators as transforming growth factor-β(TGF-β), monocyte chemoattractant protein 1(MCP-1), and regulated upon activation normal T cell expressed and secreted protein(RANTES). The robust anti-inflammatory property of vitamin D-related products allows them with a promising renoprotective therapeutic option for DN. This review summarizes new advances in our understanding of vitamin D-related products in the DN management.

Cardiovascular Autonomic Neuropathy and Glucose Variability in Patients With Type 1 Diabetes: Is There an Association?

INTRODUCTION

The oxidative stress associated with glucose variability might be responsible for neuronal damage while autonomic neuropathy (AN) has a detrimental effect on metabolism. The aim of the study was to find relationship between AN and GV in type 1 diabetic patients and to identify further factors that affect GV.

PATIENTS AND METHODS

Twenty type 1 diabetic patients were involved (age: 39.5 ± 3.4 years, duration of diabetes: 17.5 ± 2.5 years; HbA1c: 8.1 ± 0.2%, mean ± SE). AN was assessed by the cardiovascular reflex tests. The interstitial glucose levels were determined following insertion of a subcutaneous electrode during the continuous glucose monitoring (CGM) method on six consecutive days. GV was characterized by calculation of four parameters.

RESULTS

SD of interstitial glucose values correlated positively with the overall AN score and the degree of the orthostatic reduction of systolic blood pressure (AN-score-SD ρ = 0.47, p < 0.05; orthostasis-SD: ρ = 0.51, p < 0.05). Mean absolute glucose (MAG) correlated with three parameters of AN (AN-score-MAG: ρ = 0.62, p < 0.01; 30/15 ratio-MAG: ρ = -0.50, p < 0.05; orthostasis-MAG: ρ = 0.59, p < 0.01). The HbA1c also correlated with two parameters of GV (HbA1c-continuous overlapping net glycemic action: ρ = 0.56, p < 0.05; HbA1c-MAG: ρ = 0.45, p < 0.05). The frequency of hypoglycemia did not exhibit any correlation with measures of GV.

CONCLUSION

Severity of glucose variability but not overall glucose load correlates with both parasympathetic and sympathetic dysfunctions in type 1 diabetes. Higher HbA1c is associated with more severe glucose variability. The observed correlation between increased glucose variability and the severity of AN necessitates the further exploration of this relationship.