Immunohistochemical localization of the 1,25(OH)2D3 receptor and calbindin D28k in human and rat pancreas

Expression of vitamin D receptor, CYP24A1, and CYP27B1 in normal and inflamed canine pancreases

Vitamin D plays a role in anti-inflammatory processes, and the alteration of its metabolism is associated with the inflammatory processes of pancreatitis. This study was performed to evaluate the expression of the vitamin D receptor (VDR) and the two major enzymes that regulate vitamin D metabolism, 1α-hydroxylase (CYP27B1) and 24-hydroxylase (CYP24A1), in the canine pancreas and to compare their degrees of immunoreactivity between normal and inflamed pancreases. Five normal and inflamed pancreatic tissues each were obtained from six dogs. The expression of VDR, CYP24A1, and CYP27B1 were determined immunohistochemically, and the degree of immunostaining was assessed semiquantitatively. The VDR was expressed in the ducts, acini, and islets of Langerhans of normal pancreases and in the ducts and acini of inflamed ones. There was a significant difference in the immunoreactivity score for VDR in the islets of Langerhans between normal (median, 3 [interquartile range, 2-7.5] score) and inflamed pancreatic tissues (0 [0-0.5] score, p = 0.03). CYP24A1 was expressed in the ducts and islets of Langerhans in both normal and inflamed pancreases, whereas CYP27B1 was expressed in the ducts and acini in only some normal and inflamed pancreatic tissues. This study showed that VDR expression decreased in inflamed pancreases and demonstrated CYP24A1 and CYP27B1 expression in the canine pancreas for the first time. These findings indicate that the pancreas could regulate the metabolism and biological activity of vitamin D and suggest that a decrease in these might be related to the pathophysiology of pancreatitis.

Association between vitamin D and cardiovascular health: Myth or Fact? A narrative review of the evidence

Vitamin D deficiency is prevalent worldwide. Since the discovery of the expression of vitamin D receptor in ventricular cardiomyocytes, fibroblasts, and blood vessels, there has been a growing body of literature assessing the link between vitamin D status and cardiovascular health from one side, and the effect of vitamin D supplementation on prevention of cardiovascular diseases from the other side. In this review, we summarized studies highlighting the role of vitamin D on cardiovascular health, namely atherosclerosis, hypertension, heart failure, and metabolic syndrome, a recognized significant risk factor for cardiovascular diseases. Studies showed discrepancies between findings from cross-sectional and longitudinal cohorts and those from interventional trials, but also between one outcome and another. Cross-sectional studies found a strong association between low 25 hydroxyvitamin D (25(OH)D3) and acute coronary syndrome, and heart failure. These findings encouraged the promotion for vitamin D supplementation as a preventive measure for cardiovascular diseases in the elderly, namely in women. This fact, however, turned out into a myth with the results of large interventional trials that did not show any benefit from vitamin D supplementation in reducing ischemic events, heart failure or its outcomes, or hypertension. Although some clinical studies showed beneficial effect of vitamin D supplementation on insulin sensitivity and metabolic syndrome, this effect was not consistent across all studies.

Vitamin D Receptor Gene ApaI and TaqI Polymorphisms in Type 2 Diabetes among Saudi Population

Background: Variants of vitamin D receptor (VDR) gene have been linked to a variety of diseases, including metabolic syndrome, cancer, bone disease, and tuberculosis. The relationship between VDR gene mutations and the susceptibility of type 2 diabetes mellitus (T2DM) in different ethnic groups is yet unknown. Vitamin D and its receptor complex have a function in regulating β-cell insulin secretion as a transcription factor. Objectives: The goal of this study was to see if there is a link between VDR Apa1 and Taq1 polymorphisms and T2DM susceptibility in the Saudis of Makkah environ. Materials and Methods: DNA was separated from peripheral blood and genotyped in 110 healthy controls and 110 unrelated people with T2DM for the VDR ApaI (G/T) rs7975232 and TaqI (A/G) rs731236 single nucleotide polymorphisms (SNPs) using polymerase chain reaction and restriction fragment length polymorphism (PCR-RFLP) technique. Results: The distributions of genotypes and alleles of VDR ApaI and TaqI polymorphisms were statistically indifferent across the groups investigated (P >0.05). Conclusion: These findings showed that polymorphisms in the VDR ApaI and TaqI genes may not be linked to T2DM risk in Saudis.

Vitamin D and Pancreatitis: A Narrative Review of Current Evidence

Emerging research indicates that vitamin D metabolic disorder plays a major role in both acute pancreatitis (AP) and chronic pancreatitis (CP). This has been demonstrated by studies showing that vitamin D deficiency is associated with pancreatitis and its anti-inflammatory and anti-fibrotic effects by binding with the vitamin D receptor (VDR). However, the role of vitamin D assessment and its management in pancreatitis remains poorly understood. In this narrative review, we discuss the recent advances in our understanding of the molecular mechanisms involved in vitamin D/VDR signaling in pancreatic cells; the evidence from observational studies and clinical trials that demonstrate the connection among vitamin D, pancreatitis and pancreatitis-related complications; and the route of administration of vitamin D supplementation in clinical practice. Although further research is still required to establish the protective role of vitamin D and its application in disease, evaluation of vitamin D levels and its supplementation should be important strategies for pancreatitis management according to currently available evidence.

Association of vitamin D receptor gene rs739837 polymorphism with type 2 diabetes and gestational diabetes mellitus susceptibility: a systematic review and meta-analysis

Background

Increasing evidence shows that genetic variants of genes in the diabetes mellitus (DM) metabolic pathway, such as the vitamin D receptor (VDR) gene rs739837 polymorphism, increase the risk of DM susceptibility. However, the findings have been inconsistent. The present study was performed to evaluate the association of VDR gene rs739837 and type 2 diabetes (T2DM) or gestational diabetes mellitus (GDM) risk.

Methods

A comprehensive meta-analysis and a subgroup analysis were conducted to assess the association between VDR rs739837 and T2DM or GDM among five genetic models (dominant, recessive, homozygote heterozygote, and allele models) using a fixed or random model.

Results

The meta-analysis included 9 studies. In the overall analysis, the results showed that VDR rs739837 was associated with an increased risk of T2DM or GDM in the allele model (T vs. G: OR = 1.088; 95% CI: 1.018–1.163; P = 0.012) and dominant model (TT + GT vs. GG: OR = 1.095; 95% CI: 1.001–1.197; P = 0.047). In the subgroup analysis, VDR rs739837 was also associated with an increased risk of T2DM in the allele model (T vs. G: OR = 1.159; 95% CI: 1.055–1.273; P = 0.002) and dominant model (TT + GT vs. GG: OR = 1.198; 95% CI: 1.048–1.370; P = 0.008). However, VDR rs739837 was not associated with GDM.

Conclusions

Significant associations were found between the VDR rs739837 polymorphism and T2DM susceptibility, but not with GDM.

Supplementary Information

The online version contains supplementary material available at 10.1186/s40001-022-00688-x.

Effect of Intramuscular Injection of Vitamin D on 25-Hydroxyvitamin D Levels, Glycaemic Control, and Liver Enzymes in Libyan Patients with Type 2 Diabetes Mellitus

Background Vitamin D is a fat-soluble hormone that plays an important role in glycaemic control. In addition, it has a positive effect on improving liver enzyme function.

Aim This study was performed to examine the effect of intramuscular injection of vitamin D on serum 25-hydroxyvitamin D [25(OH)D] levels, glycemic control, and liver enzymes in Libyan patients suffering from type 2 diabetes mellitus (T2DM) with vitamin D deficiency.

Methods and Materials This cross-sectional study enrolled 100 T2DM (50 males and 50 females). Their serum 25(OH)D, fasting blood glucose (FBG), and liver enzymes were measured at the baseline and 12 weeks after treatment with vitamin D (200,000 IU) injection monthly for 3 months. Data analysis involved the estimation of mean ± standard error (SE) and comparison of means between pre and post-treatment values using paired t-test. Independent t-test was used to compare the means between males and females. The level of significance was set at p < 0.05.

Results Females had a lower 25(OH)D blood levels than males at baseline (7.03 ± 0.25 ng/mL versus 7.86 ± 0.26 ng/mL, respectively p < 0.02). 25(OH)D levels in both sexes was increased significantly from 7.45 ± 0.18 ng/mL to 26.69 ± 0.24 ng/mL after 12 weeks of vitamin D injections (p < 0.001), with no significant differences between male and females. FBG levels in both sexes was significantly decreased from 144.68 ± 1.84 mg/dL to 85.96 ± 0.34 mg/dL post treatment (p < 0.001). Alanine aminotransferase (ALT) was increased from 10.24 ± 0.17 U/L at baseline to 20.34 ± 1.15 U/L post treatment (p < 0.001). Similarly, aspartate aminotransferase (AST) was increased from 11.23 ± 0.21 to 20.57 ± 0.22 U/L (p < 0.001), and alkaline phosphatase (ALP) was decreased from 124.95 ± 1.15 U/L to 111.17 ± 1.27 U/L (p < 0.001). There were no significant differences between male and female liver enzymes either pre- or post-vitamin D injections

Conclusion Treatment with vitamin D injection showed a significant increase in 25(OH)D accompanied by decreased FBG and ALP levels and increased ALT and AST levels. Vitamin D levels should be monitored and adjusted in diabetic patients.

Vitamin D insufficiency is associated with metabolic syndrome independent of insulin resistance and obesity in young adults - The Berlin Aging Study II

PURPOSE

Age-related changes affect vitamin D absorption and metabolism. Low 25-hydroxyvitamin D concentrations have been reported as risk factor for the development of metabolic syndrome (MetS). However, recent evaluations suggest this association might be explained by obesity or insulin resistance (IR) in subjects with MetS. Our aim was to analyze associations between vitamin D insufficiency and MetS in a young cohort without diabetes and two senior cohorts with and without diabetes.

METHODS

Four hundred sixteen young and 1357 older BASE-II participants were analyzed. Type 2 diabetes (T2D) was defined according to European Society of Cardiology (ESC) guidelines, MetS as suggested by International Diabetes Federation/American Heart Association/National Heart, Lung and Blood Institute (IDF/AHA/NHLBI 2009). Vitamin D insufficiency was defined as 25-hydroxyvitamin D concentrations <50 nmol/L. Among other confounders, BMI and IR were taken into account.

RESULTS

MetS was prevalent in 7.7% of the young and in 35.6% of the older BASE-II participants and T2D occurred in 12.7% of the older participants. In young subjects without diabetes, vitamin D insufficiency was associated with an independent 3.2-fold increased odds of having MetS (OR: 3.2 CI: 1.0-8.7; p = 0.042). However, in the older participants, this association was lost once BMI was taken into account among those with diabetes, and once IR was taken into account among those without diabetes.

CONCLUSION

Independent associations between vitamin D insufficiency and MetS were only found among young subjects without diabetes. In the older adults, BMI annihilated these associations among subjects without diabetes as did HOMA-IR among subjects with diabetes.

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.

Vitamin D Receptor gene polymorphisms and susceptibility to type 2 diabetes: evidence from a meta-regression and meta-analysis based on 47 studies

BACKGROUND

Evidence from various studies suggest that vitamin D receptor (VDR) gene polymorphisms are associated with type 2 diabetes (T2D); However, these results have been disputable. Here we conducted a meta-analysis to comprehensively evaluate the effect of VDR gene polymorphisms and susceptibility to T2D.

METHODS

All relevant studies reporting the association between VDR gene polymorphisms and susceptibility to T2D published up to August 2020 were identified by comprehensive systematic database search in web of science, Scopus, and Medline. Pooled odds ratios (ORs) and 95% confidence intervals (CIs) were calculated to measure strength of association. The methodological quality of each study was assessed according to the Newcastle-Ottawa Scale. Subgroup and meta-regression analysis were also performed.

RESULTS

A total of 47 case-control studies were included in this meta-analysis. The overall population results revealed a significant association between FokI, and BsmI (heterozygote model) polymorphisms and T2D in the overall analysis. However, no association was found with the TaqI and ApaI polymorphisms. Moreover, the pooled results of subgroup analysis by ethnicity suggested significant association between FokI, TaqI, and BsmI polymorphisms and T2D in some subgroups. Meta-regression analyses indicated that none of the publication year, ethnicity, and genotyping method were the source of heterogenicity in all four polymorphisms.

CONCLUSIONS

This meta-analysis suggested a significant association between VDR gene FokI, and BsmI (heterozygote model) polymorphisms and T2D susceptibility in overall population and ethnic-specific analysis.

SUPPLEMENTARY INFORMATION

The online version contains supplementary material available at 10.1007/s40200-020-00704-z.

Associations Between Bioavailable Vitamin D and Remnant Cholesterol in Patients With Type 2 Diabetes Mellitus

Introduction In circulation, 99% vitamin D is transported by binding to vitamin D binding protein (VDBP) and albumin. Vitamin D at free form and vitamin D binding to albumin are defined as bioavailable vitamin D. Vitamin D deficiency is associated with atherogenic lipid profile and insulin resistance. Remnant cholesterol is defined as the cholesterol component of triglyceride-rich lipoproteins and contributes to the atherosclerotic burden. The aim of this study was to investigate the association between bioavailable vitamin D and remnant cholesterol in patients with type 2 diabetes mellitus (T2DM). Methods A total of 198 T2DM patients and 208 non-diabetic subjects underwent biochemical measurements of lipid profiles, 25(OH)D, VDBP, CRP and albumin levels. Their demographic characteristics (age, sex) were questioned. Subjects with thyroid, kidney and liver dysfunction and using lipid-lowering therapy were not included in the study. The diagnosis of T2DM was made according to the American Diabetes Association ADA 2016 criteria. Classification of vitamin D levels was done according to the Endocrine Society. Bioavailable vitamin D concentrations were calculated. Results High-density lipoprotein cholesterol (HDL), 25(OH)D, free vitamin D and bioavailable vitamin D levels were significantly lower in diabetic patients than in non-diabetic patients while triglyceride, remnant cholesterol and CRP levels were found to be significantly higher. VDBP was positively correlated with CRP and remnant cholesterol in diabetic patients, but not in non-diabetic patients. Cut-off values were determined from non-diabetics as 3.56 ng/mL for bioavailable vitamin D and 26.56 mg/dL for remnant cholesterol. Logistic regression analysis in the control group showed that the odds ratio for increasing remnant cholesterol above the cut-off value was determined as 2.01 for low bioavailable vitamin D and 1.1 for elevated CRP. However, in T2DM there was no significant relationship. In all subjects, low bioavailable vitamin D increased the remnant cholesterol above the cut-off by 2.18-fold independent of the presence of T2DM. However, there was no significant risk to increase remnant cholesterol, considering a total 25(OH) D deficiency in all groups. Conclusions Low bioavailable vitamin D was found to be a risk factor for elevated remnant cholesterol. This relationship was not detected in patients with T2DM. We believe that the inflammation observed in Diabetes Mellitus may increase the concentrations of VDBP and a decrease in bioavailable vitamin D levels. Therefore, measuring VDBP and calculating the bioavailable vitamin D may provide additional information about the actual vitamin D status.

Association between Vitamin D Receptor Polymorphisms (BsmI and FokI) and Glycemic Control among Patients with Type 2 Diabetes

(1) Background: Several studies have suggested that the vitamin D receptor (VDR) gene plays a role in type 2 diabetes mellitus (T2DM) susceptibility. Nonetheless, the association between T2DM and VDR polymorphisms remains inconclusive. We determined the genotype of VDR rs1544410 (BsmI) and rs2228570 (FokI) polymorphisms among Malaysian patients with T2DM and their association with glycemic control factors (vitamin D levels, calcium, magnesium, and phosphate). (2) Methods: A total of 189 participants comprising 126 patients with T2DM (63 with good glycemic control and 63 with poor glycemic control) and 63 healthy controls were enrolled in this case-control study. All biochemical assays were measured using spectrophotometric analysis. VDR gene FokI and BsmI polymorphisms were analyzed using polymerase chain reaction and endonuclease digestion. (3) Results: Our findings revealed no significant differences in VDR FokI and BsmI genotypes between participants with T2DM and healthy controls. Moreover, no significant association was observed between both single nucleotide polymorphisms and glycemic control factors. Participants with poor glycemic control had significantly lower serum magnesium levels and significantly higher HOMA-IR compared to the other groups. (4) Conclusions: The present study revealed that VDR gene BsmI and FokI polymorphisms were not significantly associated with T2DM.

Correlating Circulating Vitamin D3 with Aspects of the Metabolic Syndrome and Nonalcoholic Fatty Liver Disease in Healthy Female Volunteers

Background: Significant inverse correlations between circulating vitamin D3 and the presence and strength of common clinical entities influenced by insulin resistance (IR) have been reported. Among these entities are common maladies such as the metabolic syndrome (MS) and nonalcoholic fatty liver disease (NAFLD). Since hypovitaminosis D3 is considered a common worldwide health disturbance, the consequences emanating from such relationships once soundly established might reasonably be ameliorated by vitamin replacement. Accordingly, a need exists for definitive confirmatory support for the existence of these linkages particularly in ordinary, relatively healthy individuals.Methodology: Many aspects of MS and NAFLD were examined in healthy females via linear regression analyses to determine significant correlations mainly using vitamin D3 and fasting blood glucose (FBG), the latter a surrogate for IR, as independent variables.Results: A descending linear regression between vitamin D3 and FBG did not reach full statistical significance, but a negative correlation of vitamin D3 with HbA1C was statistically significant and that with circulating insulin concentrations showed a downward statistical trend. These findings are consistent with previous ones by others suggesting an ameliorating effect of vitamin D3 on IR. Body weight, body mass index (BMI), and body fat correlated statistically significantly with vitamin D3 levels, as did systolic blood pressure. Again, these correlations were negative instead of positive unlike the case when FBG was the independent variable. The significant negative correlation of ALT with vitamin D3 was also consistent with previous reports that higher circulating vitamin D3 favorably influences the extent and intensity of NAFLD.Conclusions: Employing FBG as a surrogate for IR and ALT for status of NAFLD, linear correlations reasonably suggest that increasing circulating vitamin D3 can favorably influence the initial development of and/or strength of risk factors for MS including NAFLD in relatively fit females.

The Molecular Mechanisms by Which Vitamin D Prevents Insulin Resistance and Associated Disorders

Numerous studies have shown that vitamin D deficiency is very common in modern societies and is perceived as an important risk factor in the development of insulin resistance and related diseases such as obesity and type 2 diabetes (T2DM). While it is generally accepted that vitamin D is a regulator of bone homeostasis, its ability to counteract insulin resistance is subject to debate. The goal of this communication is to review the molecular mechanism by which vitamin D reduces insulin resistance and related complications. The university library, PUBMED, and Google Scholar were searched to find relevant studies to be summarized in this review article. Insulin resistance is accompanied by chronic hyperglycaemia and inflammation. Recent studies have shown that vitamin D exhibits indirect antioxidative properties and participates in the maintenance of normal resting ROS level. Appealingly, vitamin D reduces inflammation and regulates Ca²⁺ level in many cell types. Therefore, the beneficial actions of vitamin D include diminished insulin resistance which is observed as an improvement of glucose and lipid metabolism in insulin-sensitive tissues.

Early myocardial injury biomarkers in diabetic hyperlipidemic rats: Impact of 10-dehydrogingerdione and vitamin D3

IMPACT STATEMENT

Hyperlipidemia represents a major risk factor for cardiovascular diseases leading to myocardial injury (MI). The present study aimed to illustrate the pattern of myocardial injury induced in diabetic hyperlipidemic rat model and the effect of vitamin D3, 10-dehydrogingerdione (10-DHGD) intake either individually or in combination form.

Rs739837 affects the severity of asthma by disrupting the binding of microRNA-885

Aim: This study investigated the molecular mechanism underlying the involvement of miR-885 in the signaling pathways of VDR. Results: Based on their rs739837 genotype, the subjects were divided into a case group and a control group. Logistic regression was carried out to study the impact of rs739837 genotypes on the severity of asthma, and it was found that the minor allele (T) of rs739837 significantly increased the severity of asthma. Using a luciferase assay, VDR was confirmed as a miR-885 target, with a negative regulatory relationship established between VDR and miR-885. Conclusion: The findings of this study demonstrated that VDR is an miR-885 target, while the presence of rs739837 minor allele (T) in miR-885 interferes with the interaction between miR-885 and VDR to affect the severity of asthma.

Combined Effect of Maternal Vitamin D Deficiency and Gestational Diabetes Mellitus on Trajectories of Ultrasound-Measured Fetal Growth: A Birth Cohort Study in Beijing, China

OBJECTIVE

Few studies have examined whether maternal 25(OH)D deficiency and gestational diabetes mellitus (GDM) jointly affect fetal growth. We aimed to examine the separate and combined effects of maternal 25(OH)D deficiency and GDM on trajectories of fetal growth.

METHODS

We established a birth cohort (2016-2017) with 10,913 singleton pregnancies in Tongzhou Maternal and Child Health Hospital of Beijing, China. Maternal 25(OH)D deficiency (serum 25(OH)D concentration < 20.0 ng/mL) was detected, and GDM was diagnosed at 24~28 gestational weeks. Fetal growth was assessed by longitudinal ultrasound measurements of estimated fetal weight (EFW) and abdominal circumference (AC) from 28 gestational weeks to delivery, both of which were standardized as gestational-age-adjusted Z-score. A k-means algorithm was used to cluster the longitudinal measurements (trajectories) of fetal growth. Logistic regression models were used for estimating exposure-outcome associations and additive interactions.

RESULTS

We identified two distinct trajectories of fetal growth, and the faster one resembling the 90^th centile curve in the reference population was classified as excessive fetal growth. Maternal 25(OH)D deficiency and GDM were independently associated with an increased risk of excessive fetal growth. The combination of maternal 25(OH)D deficiency and GDM was associated with an increased risk of excessive fetal growth assessed by EFW Z-score (odds ratio (OR): 1.36; 95% confidence interval (CI): 1.15~1.62) and AC Z-score (OR (95% CI): 1.32 (1.11~1.56)), but the relative excess risks attributable to interaction were nonsignificant (P > 0.05).

CONCLUSION

Maternal 25(OH)D deficiency and GDM may jointly increase the risk of excessive fetal growth. Interventions for pregnancies with GDM may be more beneficial for those with 25(OH)D deficiency than those without regarding risk of excessive fetal growth, if confirmed in a large sample.

Association of Vitamin D deficiency and Vitamin D Receptor Gene Polymorphisms with Type 2 diabetes mellitus Saudi patients

Background

Type 2 diabetes mellitus (T2DM) is a global problem. Association of multiple genes in T2DM becomes a hot point recently. This study was aimed to evaluate association of vitamin D receptor gene polymorphisms with susceptibility to T2DM.

Subjects and methods

One hundred T2DM Saudi male patients were included in this study and one hundred healthy Saudi men were used as control. For each individual, fasting blood glucose, cholesterol, HDL-C, LDL-C, HbA1c, insulin and 25-(OH) vitamin D were measured. In addition, Apal, BsmI and TaqI genotypes were performed for each subject. Data was analyzed by SPSS version 16, using Spearman's rho and ANOVA tests.

Results

There was significant inverse correlation between 25-(OH) vitamin D level and T2DM (p<0.01). HbA1c was inversely correlated with 25-(OH) vitamin D level (P<0.05). Genotype study showed that tt of TaqI genotype was higher in T2DM group compared with control group (p<0.05). Moreover, tt genotype has higher HbA1c than both TT and Tt genotypes (p<0.05).

Conclusion

An association was confirmed between TaqI genotypes and T2DM but there is no correlation between BsmI, ApaI and T2DM. In addition, HbA1c is positively correlated with tt genotype of TaqI.

Influence of Vitamin D on Islet Autoimmunity and Beta-Cell Function in Type 1 Diabetes

Type 1 diabetes (T1D) is a chronic autoimmune disease leading to immune-mediated destruction of pancreatic beta cells, resulting in the need for insulin therapy. The incidence of T1D is increasing worldwide, thus prompting researchers to investigate novel immunomodulatory strategies to halt autoimmunity and modify disease progression. T1D is considered as a multifactorial disease, in which genetic predisposition and environmental factors interact to promote the triggering of autoimmune responses against beta cells. Over the last decades, it has become clear that vitamin D exerts anti-inflammatory and immunomodulatory effects, apart from its well-established role in the regulation of calcium homeostasis and bone metabolism. Importantly, the global incidence of vitamin D deficiency is also dramatically increasing and epidemiologic evidence suggests an involvement of vitamin D deficiency in T1D pathogenesis. Polymorphisms in genes critical for vitamin D metabolism have also been shown to modulate the risk of T1D. Moreover, several studies have investigated the role of vitamin D (in different doses and formulations) as a potential adjuvant immunomodulatory therapy in patients with new-onset and established T1D. This review aims to present the current knowledge on the immunomodulatory effects of vitamin D and summarize the clinical interventional studies investigating its use for prevention or treatment of T1D.

Vitamin D status during pregnancy and the risk of gestational diabetes mellitus: A longitudinal study in a multiracial cohort

AIM

To prospectively and longitudinally investigate vitamin D status during early to mid-pregnancy in relation to gestational diabetes mellitus (GDM) risk.

METHODS

In a nested case-control study of 107 GDM cases and 214 controls within the Fetal Growth Studies-Singleton Cohort, plasma levels of 25-hydroxyvitamin D2 and D3 (25(OH)D) and vitamin D binding protein were measured at gestational weeks 10 to 14, 15 to 26, 23 to 31, and 33 to 39; we further calculated total, free, and bioavailable 25(OH)D. Conditional logistic regression models and linear mixed-effects models were used.

RESULTS

We observed a threshold effect for the relation of vitamin D biomarkers with GDM risk. Vitamin D deficiency (<50 nmol/L) at 10 to 14 gestational weeks was associated with a 2.82-fold increased risk for GDM [odds ratio (OR) = 2.82, 95% confidence interval (CI): 1.15-6.93]. Women with persistent vitamin D deficiency at 10 to 14 and 15 to 26 weeks of gestation had a 4.46-fold elevated risk for GDM compared with women persistently non-deficient (OR = 4.46, 95% CI: 1.15-17.3).

CONCLUSIONS

Maternal vitamin D deficiency as early as the first trimester of pregnancy was associated with an elevated risk of GDM. The association was stronger for women who were persistently deficient through the second trimester. Assessment of vitamin D status in early pregnancy may be clinically important and valuable for improving risk stratification and developing effective interventions for the primary prevention of GDM.

Analysis of Association between Vitamin D Deficiency and Insulin Resistance

Recent evidence revealed extra skeleton activity of vitamin D, including prevention from cardiometabolic diseases and cancer development as well as anti-inflammatory properties. It is worth noting that vitamin D deficiency is very common and may be associated with the pathogenesis of insulin-resistance-related diseases, including obesity and diabetes. This review aims to provide molecular mechanisms showing how vitamin D deficiency may be involved in the insulin resistance formation. The PUBMED database and published reference lists were searched to find studies published between 1980 and 2019. It was identified that molecular action of vitamin D is involved in maintaining the normal resting levels of ROS and Ca2+, not only in pancreatic β-cells, but also in insulin responsive tissues. Both genomic and non-genomic action of vitamin D is directed towards insulin signaling. Thereby, vitamin D reduces the extent of pathologies associated with insulin resistance such as oxidative stress and inflammation. More recently, it was also shown that vitamin D prevents epigenetic alterations associated with insulin resistance and diabetes. In conclusion, vitamin D deficiency is one of the factors accelerating insulin resistance formation. The results of basic and clinical research support beneficial action of vitamin D in the reduction of insulin resistance and related pathologies.

Serum vitamin D and diabetic foot complications

Background: Foot complications such as ulceration and neuropathy are common complications of diabetes mellitus (DM). Previous reports have demonstrated a possible increased risk of these complications in diabetic patients with low levels of serum vitamin D.Objectctive: The purpose of this study is to compare serum vitamin D levels in diabetic patients with and without Charcot neuroarthropathy (CN), peripheral arterial disease (PAD), infection (DFI), ulceration (DFU), and peripheral neuropathy (DPN). Design: A retrospective chart review of all patients undergoing foot and ankle surgery with a history of DM over a 13 month period was performed. From this cohort, fifty subjects with CN were matched with 50 without CN and preoperative lab values were compared. A secondary evaluation was performed on the subjects' other comorbidities including PAD, DFI, DFU, and DPN. Results: Seventy-eight percent of our patients had vitamin D deficiency or insufficiency. Preoperative serum vitamin D levels were not significantly different between diabetic patients with and without CN (p = 0.55). Diabetic patients with PAD (p = 0.03), DFI (p = 0.0006), and DFU (p = 0.04) were all found to have significantly lower serum vitamin D levels than diabetic patients without these complications. Lower levels of serum albumin and higher serum creatinine were also noted with subjects with PAD, DFI, DPN, and DFU. While seasonal serum vitamin D level fluctuation was noted, this difference did not reach statistical significance with the numbers available. Conclusion: We found various lower extremity complications to be associated with low serum vitamin D including PAD, DFI, and DFU. While other studies have questioned the role of vitamin D and CN, we were unable to identify any significant difference between diabetic patients with and without Charcot neuroarthropathy. Level of evidence: Level 2.

The Role of Vitamin D Binding Protein, Total and Free 25-Hydroxyvitamin D in Diabetes

Vitamin D is important for bone health, but may also have extra-skeletal effects. Vitamin D and its binding protein DBP have immunological effects and may therefore be important in the development of type 1 diabetes (T1DM), and low serum levels of 25-hydroxyvitamin D (25(OH)D) are associated with later development of type 2 diabetes (T2DM). However, it has so far been difficult to convincingly show an effect of vitamin D supplementation on prevention or treatment of diabetes. The serum level of 25(OH)D has traditionally been used as a marker of a subject's vitamin D status. This measurement includes both 25(OH)D bound to DBP and albumin as well as the free from of 25(OH)D. However, according to the free hormone hypothesis, the free form is the biologically active. Previously the free form of 25(OH)D had to be calculated based on measurements of 25(OH)D, DBP, and albumin, but recently a method for direct measurement of free 25(OH)D has become commercially available. This is important in clinical conditions where the amount of DBP is affected, and has caused a renewed interest in which vitamin D metabolite to measure in clinical situations. In the present review the relations between DBP, total and free 25(OH)D in T1DM and T2DM are described.

Single Nucleotide Polymorphisms in the Vitamin D Receptor Gene (VDR) May Have an Impact on Acute Pancreatitis (AP) Development: A Prospective Study in Populations of AP Patients and Alcohol-Abuse Controls

Vitamin D imbalance is suggested to be associated with the development of pancreatitis. Single nucleotide polymorphisms (SNPs), Apa-1, Bsm-1, Fok-1, and Taq-1, in the vitamin D receptor gene (VDR) are known in various diseases, but not yet in pancreatitis. The aim of this study was to explore possible associations of the four SNPs in the VDR receptor gene in a population of acute pancreatitis patients and alcohol-abuse controls, and to investigate the association with acute pancreatitis (AP) susceptibility. The study population (n = 239) included acute pancreatitis patients (n = 129) and an alcohol-abuse control group (n = 110). All patients met the Diagnostic and Statistical Manual of Mental Disorders (DSM IV) criteria for alcohol dependence. DNA was extracted from peripheral leukocytes and analyzed for VDR polymorphisms using a polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) method. Odd ratios (ORs) and 95% confidence intervals (CIs) were calculated using logistic regression analysis. To date, we have found allele T in Taq-1 (OR = 2.61; 95% CI: 1.68⁻4.03; p < 0.0001) to be almost three times more frequent in the AP group compared to the alcohol-abuse control patients. Polymorphism Taq-1 occurring in the vitamin D receptor may have an impact on the development of acute pancreatitis due to the lack of the protective role of vitamin D.

Prepregnancy habitual intake of vitamin D from diet and supplements in relation to risk of gestational diabetes mellitus: A prospective cohort study

BACKGROUND

Vitamin D may play a pivotal role in regulating insulin secretion and insulin sensitivity. However, the effect of vitamin D intake, either from the diet or from supplements, on the development of gestational diabetes mellitus (GDM) remains unclear. We prospectively examined the association of prepregnancy habitual intake of vitamin D from diet and supplements with the risk of incident GDM in a well-established cohort.

METHODS

The present study was performed on 21 356 singleton pregnancies from 15 225 women in the Nurses' Health Study II cohort. Diet information, including vitamin D intake from food sources and supplements, was assessed in 1991 and every 4 years thereafter by validated food frequency questionnaires. Log-binomial models with generalized estimating equations were used to estimate relative risks (RRs) and 95% confidence intervals (CIs).

RESULTS

During 10 years of follow-up, 865 incident GDM cases were documented. After adjustment for age, parity, race/ethnicity, family history of diabetes, dietary and lifestyle factors, and body mass index, the RRs (95% CIs) of GDM risk associated with supplemental vitamin D intake of 0, 1-399, and ≥400 IU/day were 1.00 (reference), 0.80 (0.67-0.96), and 0.71 (0.56-0.90), respectively (P_trend  = 0.002). Dietary and total vitamin D intakes were also inversely associated with GDM risk, but the associations were not statistically significant.

CONCLUSIONS

Prepregnancy supplemental vitamin D intake was significantly and inversely associated with risk of GDM. This study indicates potential benefits of increasing vitamin D intake from supplements in the prevention of GDM in women of reproductive age.

A double blind randomized clinical trial to investigate the effect of vitamin D supplementation on metabolic and hepato-renal markers in type 2 diabetes and obesity

Background: According to the recent studies, vitamin D deficiency has been correlated with progress in type 2 Diabetes and Metabolic Syndrome. The aim of this study was to assess the effect of vitamin D supplementation on glucose and lipid profiles, blood pressure, and biomarkers of liver and kidney in type 2 diabetic patients. Methods: In this Double blinded randomized clinical trial, 90 patients with type 2 diabetes and serum 25-Hydroxy vitamin D levels of less than 30 ng/ml recruited from "Besat Diabetes Clinic" in Rasht, North of Iran. The subjects took 50000 IU vitamin D supplements or placebo for 8 weeks. We assessed the levels of serum 25 (OH) vitamin D, glucose and lipid profiles, oxidative and inflammatory indices, liver and kidney biomarkers, blood pressure, and sun exposure time, physical activity before and after intervention, and compared them between cases and controls. Results: Vitamin D supplementation significantly increased serum vitamin D level, Superoxide Dismutase (SOD) activity, and significantly decreased serum HbA1C (Glycosylated Hemoglobin) level (p<0.001). High Density Lipoprotein (HDL) Cholesterol increased significantly (p=0.016), and Erythrocyte Sedimentation Rate (ESR) significantly decreased (p=0.039) after the intervention. Conclusion: Our results represented that weekly supplementation with 50000 IU vitamin D for 8 weeks may be effective by improving HbA1C and lipid profile in type 2 diabetes mellitus.

Evaluating Vitamin D Status in Pre- and Postmenopausal Type 2 Diabetics and Its Association with Glucose Homeostasis

Background

Type 2 Diabetes Mellitus (T2DM) and menopause are associated with vitamin D status. Oestrogen decline during menopausal stages promotes hypovitaminosis D. However, the interplay between vitamin D, menopause, lifestyle, and T2DM cannot be overlooked. This study assessed vitamin D status among pre- and postmenopausal T2DM women and determined its association with glycemic control and influence of lifestyle habits on hypovitaminosis D.

Methods

This cross-sectional study was conducted at the Komfo Anokye Teaching Hospital, Kumasi, Ghana. Structured questionnaires were administered to 192 T2DM women; blood samples were collected for estimation of 25(OH) D and insulin using ELISA. Fasting blood glucose (FBG), lipid profile, glycated haemoglobin (HbA1c), and calcium were measured. Statistical analyses were performed using Graphpad Prism 6.

Results

The prevalence of vitamin D inadequacy was 92.2%. Hypovitaminosis D was more prevalent among the postmenopausal T2DM women (63.8% versus 58.2%). Hypovitaminosis D significantly associated with insulin [R² = 0.01760, p = 0.0008], HbA1c [R² = 0.3709, p = <0.0001], and FBG [R² = 0.3465, p = 0.0001] in only the postmenopausal women.

Conclusion

Vitamin D deficiency is prevalent in pre- and postmenopausal T2DM but higher among postmenopausal women. Adequate vitamin D levels in both groups were associated with improved glucose control while hypovitaminosis D in the postmenopausal women was related to poorer glucose control. Vitamin D screening should be incorporated into management plan for T2DM to serve as an early tool for prevention of vitamin D deficiency.

Lower vitamin D levels are associated with higher blood glucose levels in Asian Indian women with pre-diabetes: a population-based cross-sectional study in North India

BACKGROUND

Asian Indian women are predisposed to develop obesity, metabolic syndrome and vitamin D deficiency. Relationship of vitamin D deficiency with blood glucose levels has not been explored in Asian Indian women with pre-diabetes.

OBJECTIVE

We evaluated the associations of serum 25-hydroxy vitamin D (25(OH)D) concentrations among adult women with the pre-diabetes residing in North India (Delhi).

METHODS

This cross-sectional population-based study involved 797 women with pre-diabetes aged 20-60 years. Blood pressure, body mass index (BMI), fasting blood glucose (FBG), extent of sun exposure and serum 25(OH)D levels were assessed. For purpose of analysis, serum 25(OH)D levels (nmol/L) were categorized in quintiles as follows: 0-21.5 (first quintile), 21.51-35.60 (second quintile), 35.61-46.50 (third quintile), 46.51-62.30 (fourth quintile) and >62.31 (fifth quintile).

RESULT

The prevalence (%) of vitamin D deficiency, insufficiency and sufficiency was 68.6, 25.9 and 5.5, respectively. Mean age (p=0.004), systolic (p=0.05) and diastolic (p=0.04) blood pressure, weight (p=0.03), BMI (p=0.04) and FBG (p=0.02) were significantly higher in subjects with vitamin D deficiency as compared with those with vitamin D insufficiency and sufficiency. Unadjusted mean values of FBG were significantly decreased in fourth (p=0.02) and fifth quintiles (p=0.030) of 25(OH)D levels as compared with second quintile. Furthermore, after adjusting for age and family income FBG levels were significantly increased in first quintile (compared with fourth (p=0.012) and fifth (p=0.018) quintiles) and second quintile (compared with fourth (p=0.003) and fifth (p=0.004) quintiles) of 25(OH)D levels, respectively.

CONCLUSION

Lower vitamin D levels are associated with higher blood glucose values in Asian Indian women with pre-diabetes. These findings need confirmation in case-control and prospective studies.

Vitamin D Receptor Gene Polymorphisms Modify Cardiometabolic Response to Vitamin D Supplementation in T2DM Patients

There is conflicting evidence on the favorable effects of vitamin D supplementation on metabolic profile in Type 2 diabetes mellitus (T2DM) patients and this might be due to genetic variations in vitamin D receptors (VDRs). Thus, we studied the metabolic effects of a 12-month vitamin D supplementation in T2DM patients according to VDR polymorphisms. A total of 204 T2DM subjects received 2000 IU vitamin D3 daily for 12 months. Serum 25(OH)D and metabolic profiles were measured at baseline and after 12 months. VDR polymorphisms (Taq-I, Bsm-I, Apa-I and Fok-I) were identified using TaqMan genotyping assays. Vitamin D supplementation significantly increased HOMA β-cell function (p = 0.003) as well as significantly decreased triglycerides, total and LDL-cholesterol (p < 0.001). The lowest increment in 25(OH)D levels was detected in patients with Fok-I CC genotypes (p < 0.0001). With vitamin D supplementation, Taq-I GG genotype carriers showed significant improvements in triglycerides, LDL- and total cholesterol, insulin, HbA1c and HOMA-IR (p < 0.005, 0.01, < 0.001, < 0.005, 0.03 and 0.01, respectively). Similarly, Bsm-I TT genotype carriers showed significant improvements in triglycerides (p = 0.01), insulin and HOMA-IR (p-values < 0.05). In conclusion, improvements in metabolic profile due to vitamin D supplementation is influenced by VDR polymorphisms, specifically for carriers of Taq-I GG and Bsm-I TT genotypes.

The Role of Vitamin D in the Prevention of Type 2 Diabetes: To D or Not to D?

Evidence on biological plausibility from mechanistic studies and highly consistent data from observational studies raise the possibility that optimizing vitamin D status may reduce the risk of type 2 diabetes. However, the observational nature of cohort studies precludes a definitive assessment of cause and effect because residual confounding or reverse causation cannot be excluded. Confounding is especially problematic with studies of vitamin D because blood 25-hydoxyvitamin D concentration is not only an excellent biomarker of vitamin D status, reflecting intake or biosynthesis, but also an excellent marker of good overall health. Results from underpowered trials and post hoc analyses of trials designed for nondiabetic outcomes do not support a role of vitamin D supplementation for prevention of type 2 diabetes among people with normal glucose tolerance. Whether vitamin D supplementation may have a role in the prevention of diabetes in high-risk populations remains to be seen. Adequately powered, randomized trials in well-defined populations (e.g., prediabetes) are ongoing and expected to establish whether vitamin D supplementation lowers risk of diabetes.

Vitamin D and diabetes mellitus: Causal or casual association?

The incidence of both type 2 and type 1 diabetes mellitus has been increasing worldwide. Vitamin D deficiency, or the awareness of its prevalence, has also been increasing. Vitamin D may have a role in the pathogenic mechanisms predisposing to type 2 diabetes by modulating insulin resistance and/or pancreatic β-cell function. Vitamin D status or elements involved in its activation or transport may also be involved in the development of type 1 diabetes mellitus through immunomodulatory role . Based on these observations a potential association between vitamin D and diabetes has been hypothesized. In this review we discuss up to date evidence linking vitamin D with the development of diabetes. Moreover, the role of vitamin D supplementation in the prevention of both types of diabetes is analysed together with its role in improving glycemic control in diabetic patients. We also address the potential role of vitamin D deficiency in the development of macro- and microvascular complications in diabetes. Finally, we provide recommendation for Vitamin D therapy in diabetes in view of current evidence and highlight areas for potential future research in this area.

Vitamin D deficiency and anemia risk in children: a review of emerging evidence

There has been renewed scientific interest in the sequelae of vitamin D deficiency, given the emerging evidence on the diverse biologic functions of vitamin D, besides its fundamental role in bone and mineral metabolism. For the past decade, the evidence in the medical literature pointing to a relationship between anemia risk and vitamin D deficiency has been accumulating. This paper critically reviews the current evidence linking vitamin D deficiency to anemia risk in children. The synthesized evidence indicates that the studies, which were preponderantly conducted among the adult population, not only reported a bidirectional relationship between vitamin D deficiency and anemia but also showed a racial effect. In studies conducted among children, similar results were reported. Although the causal association of vitamin D deficiency with anemia risk (especially iron-deficiency anemia) remains debatable, the noncalcemic actions of the vitamin and its analogs hold prospects for several novel clinical applications. There is, however, unanimity in many reports suggesting that vitamin D deficiency is directly associated with anemia of chronic disease or inflammation. Despite the advances in unraveling the role of vitamin D in iron homeostasis, further research is still required to validate causality in the relationship between vitamin D deficiency and anemia, as well as to determine its optimal dosing, the ideal recipients for therapeutic intervention, and the preferred analogs to administer.

Vitamin D and Chronic Diseases

Vitamin D is one of the essential nutrients to sustain the human health. As a member of the steroid hormone family, it has a classic role in regulating metabolism of calcium and a non-classic role in affecting cell proliferation and differentiation. Epidemiological studies have shown that 25OHD deficiency is closely associated with common chronic diseases such as bone metabolic disorders, tumors, cardiovascular diseases, and diabetes. 25OHD deficiency is also a risk factor for neuropsychiatric disorders and autoimmune diseases. 25OHD deficiency is highly prevalent in the world. It is therefore necessary to know the adverse health effects of 25OHD deficiency, and to design interventions and early treatments for those who are likely to have low levels of 25OHD.

Vitamin D status and its association with insulin resistance among type 2 diabetics: A case -control study in Ghana

Background

Vitamin D plays a major role in physiological processes that modulate mineral metabolism and immune function with probable link to several chronic and infectious conditions. Emerging data suggests a possible influence of vitamin D on glucose homeostasis. This study sought to provide preliminary information on vitamin D status among Ghanaian type 2 diabetics and assessed its association with glucose homeostasis.

Methods

In a case control study, 118 clinically diagnosed Type 2 Diabetes Mellitus (T2DM) patients attending Diabetic Clinic at the Nkawie Government Hospital were enrolled between October and December 2015. Hundred healthy non-diabetics living in Nkawie district were selected as controls. Structured questionnaires were administered to obtain socio-demographic data. Venous blood samples were taken from both cases and controls to estimate their FBG, Lipid profile spectrophotometrically and IPTH, 25OHD by ELISA. Statistical analyses were performed using SPSS v20.0 Statistics.

Results

The average age of the study participants was 58.81years for cases and 57.79year for controls. There was vitamin D deficiency of 92.4% among T2DM cases and 60.2% among the non diabetic controls. Vitamin D deficiency did not significantly associate with HOMA-β [T2DM: r² = 0.0209, p = 0.1338 and Control: r² = 0.0213, p = 0.2703] and HOMA-IR [T2DM: r² = 0.0233, p = 0.1132 and Control: r² = 0.0214, p = 0.2690] in both the controls and the cases.

Conclusion

Vitamin D deficiency is prevalent in both T2DM and non-diabetics. There is no association between vitamin D deficiency and insulin resistance or beta cell function in our study population. Vitamin D supplementation among type 2 diabetics is recommended.

Effects of Vitamin D deficiency treatment on metabolic markers in Hashimoto thyroiditis patients

Background:

The aim of the current trial was to investigate the effect of Vitamin D treatment on metabolic markers in people with Vitamin D deficiency and thyroid autoimmunity.

Materials and Methods:

In this double-blind, randomized, placebo-controlled clinical trial, 65 Vitamin D deficient euthyroid or hypothyroid patients with positive TPO-Ab were enrolled. They randomly allocated into two groups to receive oral Vitamin D_{3 (}50000 IU weekly) and placebo for 12 weeks. Serum concentration of calcium, phosphorus, albumin, C-reactive protein, blood urea nitrogen, creatinine, glycated hemoglobin (HbA1c), insulin, fasting plasma glucose (FPG), triglyceride (TG), total cholesterol, and high-density lipoprotein were measured in both groups before and after the trial. Homeostasis model assessment estimates of beta cell function (HOMA-B) and HOMA-insulin resistance (HOMA-IR) were calculated before and after trial in both groups.

Results:

Thirty-three and thirty-two participants were allocated to Vitamin D-treated and placebo-treated groups, respectively. Mean (standard error) level of Vitamin D increased significantly in Vitamin D-treated group (45.53 [1.84] ng/mL vs. 12.76 [0.74] ng/mL, P = 0.001). The mean of HbA1c and insulin was increased significantly both in Vitamin D-treated and placebo-treated groups (P < 0.05). Other variables did not meet a significant change after trial (P = NS). In between-group comparison, there was not any significant difference between Vitamin D-treated and placebo-treated groups regarding measures of HOMA-B, HOMA-IR, FPG, HbA1c, and TG (P = NS).

Conclusion:

Our findings showed that weekly 50000 IU oral Vitamin D3 for 12 weeks did not improve metabolic markers, IR, or insulin secretion in Vitamin D deficient patients with Hashimoto thyroiditis.

Neurochemical Markers in the Mammalian Brain: Structure, Roles in Synaptic Communication, and Pharmacological Relevance

BACKGROUND

Knowledge of molecular marker (typically protein or mRNA) expression in neural systems can provide insight to the chemical blueprint of signal processing and transmission, assist in tracking developmental or pathological progressions, and yield key information regarding potential medicinal targets. These markers are particularly relevant in the mammalian brain in the light of its unsurpassed cellular diversity. Accordingly, molecular expression profiling is rapidly becoming a major approach to classify neuron types. Despite a profusion of research, however, the biological functions of molecular markers commonly used to distinguish neuron types remain incompletely understood. Furthermore, most molecular markers of mammalian neuron types are also present in other organs, therefore complicating considerations of their potential pharmacological interactions.

OBJECTIVE

Here, we survey 15 prominent neurochemical markers from five categories, namely membrane transporters, calcium-binding proteins, neuropeptides, receptors, and extracellular matrix proteins, explaining their relation and relevance to synaptic communication.

METHOD

For each marker, we summarize fundamental structural features, cellular functionality, distributions within and outside the brain, as well as known drug effectors and mechanisms of action.

CONCLUSION

This essential primer thus links together the cellular complexity of the brain, the chemical properties of key molecular players in neurotransmission, and possible biomedical opportunities.

Association of VDBP and CYP2R1 gene polymorphisms with vitamin D status in women with polycystic ovarian syndrome: a north Indian study

PURPOSE

Polycystic ovarian syndrome (PCOS) is the most common endocrine abnormality among women of reproductive age and is usually associated with oligo-ovulation/anovulation, obesity, and insulin resistance. Hypovitaminosis D may also be a primary factor in the initiation and development of PCOS. However, little is known about the role of genetic variation in vitamin D metabolism in PCOS aetiology. Therefore, we studied the genetic polymorphisms of CYP2R1 and vitamin D binding protein (VDBP) in an Indian population.

METHODS

Serum vitamin D was measured by ELISA. Genotyping of VDBP single nucleotide polymorphisms (SNPs) rs7041 (HaeIII; G>T) and rs4588 (StyI; A>C) and CYP2R1 SNP rs2060793 (HinfI; A>G) was carried out by restriction fragment length polymorphism in 50 cases of PCOS that were compared with 50 age-matched healthy women.

RESULTS

Vitamin D levels were found to be significantly lower in women with PCOS (p = 0.008) than in age-matched controls. There was no significant difference in genotype frequencies of all three polymorphisms (rs7041, rs4588, and rs2060793) between PCOS and control women. In women with a vitamin D deficiency (<20 ng/ml), the GT allele of the VDBP SNP rs7041 (p value =0.04), the VDBP allelic combination Gc1F/1F (T allele of rs4588 and C allele of rs7041) (p value =0.03), and the GA allele of the CYP2R1 SNP rs2060793 (p = 0.05) were associated with an increased risk of developing PCOS.

CONCLUSIONS

The present study shows that the GT allele of VDBP SNP rs7041, the VDBP allelic combination (GC1F/1F), and GA allele of CYP2R1 SNP rs2060793 in vitamin D deficient women increase the risk of PCOS.

Tie-2Cre mediated deletion of the vitamin D receptor gene leads to improved skeletal muscle insulin sensitivity and glucose tolerance

A variety of studies have suggested that vitamin D may play a palliative role in improving insulin secretion and glucose tolerance. Endothelial cells of the microcirculation are thought to play an important role in regulating both insulin secretion and insulin sensitivity in target tissues. We have selectively deleted the vitamin D receptor (VDR) gene in endothelial cells of the murine vasculature. These mice demonstrate improved glucose tolerance, improved insulin sensitivity in skeletal muscle, but not in liver, and a reduction in expression and secretion of insulin in the pancreatic islets. Collectively, these data, taken within the context of recent publications in this field, suggest that the endothelial cell VDR plays a tonic inhibitory role in regulating glucose disposal and could prove to be a factor in controlling glucose homeostasis in the intact organism.

Adequate vitamin D status is associated with the reduced odds of prevalent diabetic retinopathy in African Americans and Caucasians

BACKGROUND

Vitamin D status has been hypothesized to protect against development of diabetic retinopathy via its anti-inflammatory and anti-angiogenic properties. Additionally, in vitro and in vivo studies suggest vitamin D favorably influences blood pressure and blood glucose control, strong risk factors for diabetic retinopathy. We examined the association between vitamin D status and prevalent diabetic retinopathy in participants with diabetes from a population-based cohort.

METHODS

Among participants in the Atherosclerosis Risk in Communities (ARIC) study with diabetes at visit 3 (1993-1995), 1339 (906 Caucasians, 433 African Americans) had serum 25-hydroxyvitamin (25[OH]D) concentrations assessed at visit 2 (1989-1992) and nonmydriatic retinal photographs taken at visit 3. Dietary intake of vitamin D was assessed at visit 1 (1987-1989). Logistic regression was used to estimate odds ratios (ORs) and 95 % confidence intervals (CIs) for diabetic retinopathy by categories of season-adjusted 25(OH)D (<30 [referent], 30-<50, 50-<75 and ≥75 nmol/L), by quartile of vitamin D intake (IU/day), and use of vitamin D or fish oil supplements (yes/no). P for trend was estimated using continuous 25(OH)D or vitamin D intake. ORs were adjusted for race, and duration of diabetes. We further adjusted for HBA1c and hypertension to examine if 25(OH)D influenced diabetic retinopathy via its effects on either glycemic control or blood pressure.

RESULTS

ORs (95 % CIs) for retinopathy, adjusted for race and duration, were 0.77 (0.45-1.32), 0.64 (0.37-1.10), and 0.39 (0.20-0.75), p for trend = 0.001, for participants with 25(OH)D of 30-<50, 50-<75, and ≥75 nmol/L, respectively. Further adjustment for hypertension minimally influenced results (data not show), but adjustment for HBA1c attenuated the OR among those with 25(OH)D ≥75 (0.47 [0.23-0.96], p for trend = 0.030). No statistically significant association was observed between vitamin D intake from foods or supplements and retinopathy.

CONCLUSIONS

25(OH)D concentrations ≥75 nmol/L were associated with lower odds of any retinopathy assessed 3 years later. We speculate this may be due in part to vitamin D's influence on blood glucose control.

Rationale and design of Diabetes Prevention with active Vitamin D (DPVD): a randomised, double-blind, placebo-controlled study

INTRODUCTION

Recent research suggests that vitamin D deficiency may cause both bone diseases and a range of non-skeletal diseases. However, most of these data come from observational studies, and clinical trial data on the effects of vitamin D supplementation on individuals with pre-diabetes are scarce and inconsistent. The aim of the Diabetes Prevention with active Vitamin D (DPVD) study is to assess the effect of eldecalcitol, active vitamin D analogue, on the incidence of type 2 diabetes among individuals with pre-diabetes.

METHODS AND ANALYSIS

DPVD is an ongoing, prospective, multicentre, randomised, double-blind and placebo-controlled outcome study in individuals with impaired glucose tolerance. Participants, men and women aged ≥30 years, will be randomised to receive eldecalcitol or placebo. They will also be given a brief (5-10 min long) talk about appropriate calorie intake from diet and exercise at each 12-week visit. The primary end point is the cumulative incidence of type 2 diabetes. Secondary endpoint is the number of participants who achieve normoglycaemia at 48, 96 and 144 weeks. Follow-up is estimated to span 144 weeks.

ETHICS AND DISSEMINATION

All protocols and an informed consent form comply with the Ethics Guideline for Clinical Research (Japan Ministry of Health, Labour and Welfare). The study protocol has been approved by the Institutional Review Board at Kokura Medical Association and University of Occupational and Environmental Health. The study will be implemented in line with the CONSORT statement.

TRIAL REGISTRATION NUMBER

UMIN000010758; Pre-results.

25-Hydroxyvitamin D and Parathyroid Hormone Levels Are Independently Associated with the Hemoglobin A1c Level of Korean Type 2 Diabetic Patients: The Dong-Gu Study

In type 2 diabetic patients, the relationships between 25-hydroxyvitamin D and parathyroid hormone levels, and glycemic control, remain unclear. We evaluated associations between 25-hydroxyvitamin D, parathyroid hormone, and hemoglobin A_1c levels after adjusting for other covariates, including log transformed 25-hydroxyvitamin D levels and log transformed parathyroid hormone levels, in Korean patients with type 2 diabetes. In total, 1,175 patients with type 2 diabetes were selected from 8,857 individuals who completed the baseline survey of the Dong-gu study, conducted in Korea from 2007 to 2010. After adjusting for other covariates, we found that the mean hemoglobin A_1c level was inversely associated with the 25-hydroxyvitamin D level (Q1: 7.47% [7.30–7.63], Q2: 7.25% [7.09–7.40], Q3: 7.17% [7.02–7.32], Q4: 7.19% [7.02–7.35]; p for trend = 0.021, p for between groups = 0.050) and the parathyroid hormone level (Q1: 7.35% [7.19–7.51], Q2: 7.34% [7.19–7.50], Q3: 7.28% [7.13–7.43], Q4: 7.09% [6.94–7.24]; p for trend = 0.022, p for between groups = 0.048). However, the mean fasting glucose level was not associated with either the 25-hydroxyvitamin D or parathyroid hormone level. In conclusion, inverse associations were evident between hemoglobin A_1c, 25-hydroxyvitamin D and parathyroid hormone levels in Korean patients with type 2 diabetes. The associations remained significant after adjusting for other covariates, including the log transformed 25-hydroxyvitamin D levels and log transformed parathyroid hormone levels.

Metabolic effects of vitamin D supplementation in vitamin D deficient patients (a double-blind clinical trial)

BACKGROUND

Vitamin D has recently been given a lot of attention for its role in controlling insulin secretion. Many studies have spoken of its role in weight management, blood sugar control and many other metabolic variables.

PATIENT AND METHODS

In a randomized double-blind clinical trial, 210 people with vitamin D deficiency were randomly allocated into two groups receiving vitamin D (50,000 units per week) or placebo for 8 weeks.

RESULTS

Vitamin D levels were significantly increased in the group receiving vitamin D supplementation (13.7±5.2 unit increase versus 0.8±2.8). The increased levels of vitamin D lead to significant changes in fasting insulin levels (6.8±8.1 unit reduction versus 2.3±3.7), a 2-h insulin (31.1±34.9 unit reduction versus 4.5±24.6) and Homeostasis Model Assessment (HOMA) indices.

CONCLUSION

Correction of vitamin D deficiency leads to increased insulin sensitivity that was significantly able to maintain glucose in the normal range with lower levels of insulin.

Mechanisms of Enhancer-mediated Hormonal Control of Vitamin D Receptor Gene Expression in Target Cells

The biological actions of 1,25-dihydroxyvitamin D3 (1,25(OH)2D3) are mediated by the vitamin D receptor (VDR), whose expression in bone cells is regulated positively by 1,25(OH)2D3, retinoic acid, and parathyroid hormone through both intergenic and intronic enhancers. In this report, we used ChIP-sequencing analysis to confirm the presence of these Vdr gene enhancers in mesenchyme-derived bone cells and to describe the epigenetic histone landscape that spans the Vdr locus. Using bacterial artificial chromosome-minigene stable cell lines, CRISPR/Cas9 enhancer-deleted daughter cell lines, transient transfection/mutagenesis analyses, and transgenic mice, we confirmed the functionality of these bone cell enhancers in vivo as well as in vitro. We also identified VDR-binding sites across the Vdr gene locus in kidney and intestine using ChIP-sequencing analysis, revealing that only one of the bone cell-type enhancers bound VDR in kidney tissue, and none were occupied by the VDR in the intestine, consistent with weak or absent regulation by the 1,25(OH)2D3 hormone in these tissues, respectively. However, a number of additional sites of VDR binding unique to either kidney or intestine were present further upstream of the Vdr gene, suggesting the potential for alternative regulatory loci. Importantly, virtually all of these regions retained histone signatures consistent with those of enhancers and exhibited unique DNase I hypersensitivity profiles that reflected the potential for chromatin access. These studies define mechanisms associated with hormonal regulation of the Vdr and hint at the differential nature of VDR binding activity at the Vdr gene in different primary target tissues in vivo.

Circadian rhythm of serum 25 (OH) vitamin D, calcium and phosphorus levels in the treatment and management of type-2 diabetic patients

The circadian time structure of serum 25 (OH) vitamin D (25-OHD), calcium (Ca) and phosphorus (P) may prove to be helpful in prevention, efficacy and management of diabetes mellitus. Ten newly diagnosed patients with type-2 diabetes mellitus (6 men and 4 women), 30-65 years of age, and 10 age-matched clinically healthy volunteers (7 men and 3 women) were synchronized for one week with diurnal activity from about 06:00 to about 22:00 and nocturnal rest. Breakfast was served around 08:00, lunch around 13:30 and dinner around 20:00. Drugs/nutraceuticals known to affect the vitamin D-calcium metabolism and status were not taken. Blood samples were collected at 6-h intervals for 24 h under standardized, 24-h synchronized conditions. Serum 25-OHD, Ca, P, Ca-P product and Ca-P ratio were determined. A marked circadian variation was demonstrated for 25-OHD in healthy volunteers (p = 0.030) and of borderline statistical significance in the diabetic patients (p = 0.083) by population-mean cosinor analysis. Similarly, healthy volunteers showed borderline significance for serum Ca, P and Ca-P ratio. The circadian acrophase of Ca occurred later in the patients as compared to healthy controls. Mapping the circadian rhythm (an important component of the broader time structure or chronome, which includes a.o., trends with age and extra-circadian components) of vitamin D and calcium is needed for exploring their role as markers in the treatment and management of diabetic patients.

Effect of vitamin D supplementation on insulin kinetics and cardiovascular risk factors in polycystic ovarian syndrome: a pilot study

To assess the effect of vitamin D supplementation on parameters of insulin sensitivity/resistance (IS/IR) and insulin secretion in subjects with polycystic ovarian syndrome (PCOS). A prospective double-blind randomized control trial was conducted to assess the effect of vitamin D on insulin kinetics in women with PCOS. The trial was conducted in a tertiary care research hospital. A total of 36 subjects with PCOS, aged 18-35 years, were included in this study. Vitamin D3 4000 IU/day versus placebo was given once a month for 6 months and both groups received metformin. IS (by whole-body IS index or Matsuda index), IR (by homeostasis model assessment IR (HOMA-IR)), and insulin secretion (by insulinogenic index; II30) were the main outcome measures. Secondary outcome included blood pressure (BP), lipid profile, disposition index (DI), and vascular stiffness. Out of 36 subjects who consented, 32 completed the study. Subjects were randomized into two groups: group A (n=15; metformin and vitamin D 4000 IU/day) or group B (n=17; metformin and placebo). Oral glucose tolerance tests with 75 g glucose were carried out at baseline and 6 months after supplementation. Hypovitaminosis D was observed in 93.8% of all subjects with mean serum 25 hydroxy vitamin D level of 7.30±4.45 ng/ml. After 6 months of vitamin D supplementation, there was no significant difference in any of the parameters of IS/IR (area under curve (AUC)-glucose, AUC-insulin, insulin:glucose ratio, HOMA-IR, Matsuda index, insulinogenic index, and DI), II30, and cardiovascular risk factors between the two groups. Supplementation of vitamin D, at a dose of 4000 IU/day for 6 months, did not have any significant effect on parameters of IS/IR and insulin secretion in subjects with PCOS.

Cholecalciferol supplementation does not influence β-cell function and insulin action in obese adolescents: a prospective double-blind randomized trial

BACKGROUND

There is increasing interest in the extraskeletal effects of vitamin D, particularly in the obese state with regard to the development of insulin resistance and diabetes.

OBJECTIVE

The objective of the study was to determine the effect of 2 doses of cholecalciferol (vitamin D3) supplementation on insulin action (Si) and pancreatic β-cell function in obese adolescents.

METHODS

We performed a 12-wk double-blind, randomized comparison of the effect of vitamin D3 supplementation on Si and β-cell function in obese Caucasian adolescents (body mass index > 95(th) percentile). The subjects were randomly assigned to receive either 400 IU/d (n = 25) or 2000 IU/d (n = 26) of vitamin D3. Each subject underwent a 7-sample 75 g oral glucose tolerance test, with glucose, insulin, and C-peptide measurements, to calculate Si and β-cell function as assessed by the disposition index (DI), with use of the oral minimal model before and after supplementation. A total of 51 subjects aged 15.0 ± 1.9 y were enrolled. Included for analysis at follow-up were a total of 46 subjects (20 male and 26 female adolescents), 23 in each group.

RESULTS

Initial serum 25-hydroxyvitamin D [25(OH)D] was 24.0 ± 8.1 μg/L. There was no correlation between 25(OH)D concentrations and Si or DI. There was a modest but significant increase in 25(OH)D concentration in the 2000 IU/d group (3.1 ± 6.5 μg/L, P = 0.04) but not in the 400 IU/d group (P = 0.39). There was no change in Si or DI following vitamin D3 supplementation in either of the treatment groups (all P > 0.10).

CONCLUSIONS

The current study shows no effect from vitamin D3 supplementation, irrespective of its dose, on β-cell function or insulin action in obese nondiabetic adolescents with relatively good vitamin D status. Whether obese adolescents with vitamin D deficiency and impaired glucose metabolism would respond differently to vitamin D3 supplementation remains unclear and warrants further studies. This trial was registered at clinicaltrials.gov as NCT00858247.

The relationship between serum 25-hydroxy vitamin D and insulin sensitivity and β-cell function in newly diagnosed type 2 diabetes

The aim of this study was to investigate the relationship between serum 25-hydroxy vitamin D (25-OHD) and insulin sensitivity and β-cell function in newly diagnosed type 2 diabetes. 395 newly diagnosed type 2 diabetes patients were enrolled in this study. Venous blood samples were collected at 0 min, 30 min, and 120 min of OGTT to measure serum glucose and insulin. Matsuda ISI and HOMA-IR were used to determine insulin sensitivity. The ratio of 0-120 min area under curve of insulin to glucose (insulin release index, INSR) was calculated as surrogate index of β-cell insulin secretion function. The products of insulin secretion indices multiplied by Matsuda insulin sensitivity index were used as disposition indices. Patients were divided into three groups according to tertiles (T1, T2, and T3) of 25-OHD concentration. There was significant difference among three groups for HOMA-IR, Matsuda ISI, and INSR. HOMA-IR, Matsuda ISI, INSR, and DI were undifferentiated among three groups in male patients. But HOMA-IR, Matsuda ISI, and INSR were significantly different among three groups in female patients after being adjusted by confounding factors. In conclusion, serum 25-OHD is associated with insulin sensitivity and β-cell function for female newly diagnosed type 2 diabetes patients, and the association is ambiguous in males.

VITamin D supplementation in renAL transplant recipients (VITALE): a prospective, multicentre, double-blind, randomized trial of vitamin D estimating the benefit and safety of vitamin D3 treatment at a dose of 100,000 UI compared with a dose of 12,000 UI in renal transplant recipients: study protocol for a double-blind, randomized, controlled trial

Background

In addition to their effects on bone health, high doses of cholecalciferol may have beneficial non-classic effects including the reduction of incidence of type 2 diabetes mellitus, cardiovascular disease, and cancer. These pleiotropic effects have been documented in observational and experimental studies or in small intervention trials. Vitamin D insufficiency is a frequent finding in renal transplant recipients (RTRs), and this population is at risk of the previously cited complications.

Methods/design

The VITALE study is a prospective, multicentre, double-blind, randomized, controlled trial with two parallel groups that will include a total of 640 RTRs. RTRs with vitamin D insufficiency, defined as circulating 25-hydroxyvitamin D levels of less than 30 ng/ml (or 75 nmol/l), will be randomized between 12 and 48 months after transplantation to blinded groups to receive vitamin D₃ (cholecalciferol) either at high or low dose (respectively, 100,000 UI or 12,000 UI every 2 weeks for 2 months then monthly for 22 months) with a follow-up of 2 years. The primary objective of the study is to evaluate the benefit/risk ratio of high-dose versus low-dose cholecalciferol on a composite endpoint consisting of de novo diabetes mellitus; major cardiovascular events; de novo cancer; and patient death. Secondary endpoints will include blood pressure (BP) control; echocardiography findings; the incidences of infection and acute rejection episodes; renal allograft function using estimated glomerular filtration rate; proteinuria; graft survival; bone mineral density; the incidence of fractures; and biological relevant parameters of mineral metabolism.

Discussion

We previously reported that the intensive cholecalciferol treatment (100 000 IU every 2 weeks for 2 months) was safe in RTR. Using a pharmacokinetic approach, we showed that cholecalciferol 100,000 IU monthly should maintain serum 25-hydroxyvitamin D at above 30 ng/ml but below 80 ng/ml after renal transplantation. Taken together, these results are reassuring regarding the safety of the cholecalciferol doses that will be used in the VITALE study. Analysis of data collected during the VITALE study will demonstrate whether high or low-dose cholecalciferol is beneficial in RTRs with vitamin D insufficiency.

Trial registration

ClinicalTrials.gov Identifier: NCT01431430.

Electronic supplementary material

The online version of this article (doi:10.1186/1745-6215-15-430) contains supplementary material, which is available to authorized users.

The relationship between low maternal serum vitamin D levels and glycemic control in gestational diabetes assessed by HbA1c levels: an observational cross-sectional study

Background

A great association between vitamin D deficiency and type 2 diabetes mellitus has been suggested in literature. During pregnancy, this deficiency is even more critical. It appears that vitamin D insufficiency during pregnancy may be associated with maternal hazards. The aim of this study was to assess the relation between the levels of 25-hydroxy-cholecalciferol (vitamin D), and the glycemic control in pregnant women.

Methods

An observational cross-section study including 160 pregnant women between 20-40 years in age, in their third trimester, divided into two equal groups. First group consisted of 80 women with established diagnosis of gestational diabetes and the second group with proved normal blood glucose levels. We assessed vitamin D in serum, fasting blood glucose, serum insulin and glycosylated hemoglobin (HbA1c) levels and we depicted the insulin sensitivity using the Quantitative insulin sensitivity check index (Quicki). The results were collected and statistically correlated.

Results

The mean vitamin D levels were 46.61 ± 6.087 and 47.25 ± 10.181in controls and women with gestational diabetes mellitus (GDM) respectively. The fasting insulin levels were significantly higher in the group with GDM with a mean of 18.51 ± 6.44 compared to 8.95 ± 2.52 in the control group.

The correlation coefficient (r) between HbA1c levels and Vitamin D level was -0.492 with a P value <0.05. Similar associations were also found with the fasting blood sugar levels (r = - 0.386) and with Quicki values (r = -0.250). Vitamin D levels correlated significantly with the fasting blood glucose, the fasting serum insulin and the HbA1c levels, the P value in all these correlations were <0.05. The P value with Quicki results was 0.064.

Conclusions

There is a statistically significant negative correlation between the glycemic control and vitamin D levels in serum in the whole study population. The effect of adequate vitamin D replacement on glycemic control was not studied in our work correlation. We suggest larger scale studies addressing this issue.

Effects of calcium-vitamin D co-supplementation on metabolic profiles in vitamin D insufficient people with type 2 diabetes: a randomised controlled clinical trial

AIMS/HYPOTHESIS

This study was performed to assess the effects of vitamin D and calcium supplementation on the metabolic profiles of vitamin D insufficient persons with type 2 diabetes.

METHODS

In a parallel designed randomised placebo-controlled clinical trial, a total of 118 non-smoker individuals with type 2 diabetes and insufficient 25-hydroxyvitamin D, aged >30 years, were recruited from the Isfahan Endocrine and Metabolism Research Centre. Participants were randomly assigned to four groups receiving: (1) 50,000 U/week vitamin D + calcium placebo; (2) 1,000 mg/day calcium + vitamin D placebo; (3) 50,000 U/week vitamin D + 1,000 mg/day calcium; or (4) vitamin D placebo + calcium placebo for 8 weeks. A study technician carried out the random allocations using a random numbers table. All investigators, participants and laboratory technicians were blinded to the random assignments. All participants provided 3 days of dietary records and 3 days of physical activity records throughout the intervention. Blood samples were taken to quantify glycaemic and lipid profiles at study baseline and after 8 weeks of intervention.

RESULTS

30 participants were randomised in each group. During the intervention, one participant from the calcium group and one from the vitamin D group were excluded because of personal problems. Calcium-vitamin D co-supplementation resulted in reduced serum insulin (changes from baseline: -14.8 ± 3.9 pmol/l, p = 0.01), HbA1c [-0.70 ± 0.19% (-8.0 ± 0.4 mmol/mol), p = 0.02], HOMA-IR (-0.46 ± 0.20, p = 0.001), LDL-cholesterol (-10.36 ± 0.10 mmol/l, p = 0.04) and total/HDL-cholesterol levels (-0.91 ± 0.16, p = 0.03) compared with other groups. We found a significant increase in QUICKI (0.025 ± 0.01, p = 0.004), HOMA of beta cell function (HOMA-B; 11.8 ± 12.17, p = 0.001) and HDL-cholesterol (0.46 ± 0.05 mmol/l, p = 0.03) in the calcium-vitamin D group compared with others.

CONCLUSIONS/INTERPRETATION

Joint calcium and vitamin D supplementation might improve the glycaemic status and lipid profiles of vitamin D insufficient people with type 2 diabetes.

TRIAL REGISTRATION

ClinicalTrials.gov NCT01662193 FUNDING: Clinical Research Council, Isfahan University of Medical Sciences, Isfahan, Iran.