Vitamin D and diabetes: its importance for beta cell and immune function

Molecular effects of Vitamin-D and PUFAs metabolism in skeletal muscle combating Type-II diabetes mellitus

Multiple post-receptor intracellular alterations such as impaired glucose transfer, glucose phosphorylation, decreased glucose oxidation, and glycogen production contribute to insulin resistance (IR) in skeletal muscle, manifested by diminished insulin-stimulated glucose uptake. Type-2 diabetes mellites (T2DM) has caused by IR, which is also seen in obese patients and those with metabolic syndrome. The Vitamin-D receptor (VDR) and poly unsaturated fatty acids (PUFAs) roles in skeletal muscle growth, shapes, and function for combating type-2 diabetes have been clarified throughout this research. VDR and PUFAs appears to show a variety of effects on skeletal muscle, in addition it shows a promising role on bone and mineral homeostasis. Individuals having T2DM are reported to suffer from severe muscular weakness and alterations in shape of the muscle. Several studies have investigated the effect on VDR on muscular strength and mass, which leads to Vitamin-D deficiency (VDD) in individuals, in which most commonly seen in elderly. VDR has been shown to affect skeletal cellular proliferation, intracellular calcium handling, as well as genomic activity in a variety of different ways such as muscle metabolism, insulin sensitivity, which is the major characteristic pathogenesis for IR in combating T2DM. The identified VDR gene polymorphisms are ApaI, TaqI, FokI, and BsmI that are associated with T2DM. This review collates informations on the mechanisms by which VDR activation takes place in skeletal muscles. Despite the significant breakthroughs made in recent decades, various studies show that IR affects VDR and PUFAs metabolism in skeletal muscle. Therefore, this review collates the data to show the role of VDR and PUFAs in the skeletal muscles to combat T2DM.

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

AIMS

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

Determinants of Vitamin D deficiency among type 2 diabetes mellitus patients: A retrospective study

Recent studies have shown an association between vitamin D deficiency (VDD) and type 2 diabetes mellitus patients (T2DM), but the precise relationship between these conditions has yet to be clarified. In this study, we aimed to estimate the incidence of VDD among diabetic patients and identify any relationship between diabetes and the determinants of VDD among T2DM individuals. A retrospective cross-sectional study was conducted at King Abdulaziz University Hospital, Jeddah, Saudi Arabia. Patients of either gender were selected from electronic records and checked for vitamin D levels, glycosylated hemoglobin (HbA1c), and other parameters. A total of 864 subjects were enrolled. Subjects were grouped according to HbA1c levels, with < 5.7%, 5.7% to 6.49%, and > 6.5% considered normal, impaired, and diabetic, respectively. VDD was common, with an incidence of 723 (83.7%) subjects. A significantly lower vitamin D level was found in diabetic subjects than in nondiabetic subjects (29.1 ± 12.0 vs 44.0 ± 28.3, P < .001). A total of 207/209 (99%) subjects with impaired HbA1c and 179/183 (97.8%) people with diabetes had VDD. Interestingly, none of the diabetic or impaired HbA1c subjects had normal vitamin D levels. A significant association was found between VDD and being > 50 years old, overweight, or obese, as well as HbA1c, fasting plasma glucose, calcium, and total cholesterol (TC) levels. A high rate of VDD and significantly lower vitamin D levels were found in diabetic subjects. Age, being overweight, obesity, HbA1c, and fasting plasma glucose were the few determinants of VDD among T2DM patients. These findings highlight the importance of addressing vitamin D status in managing and preventing T2DM, particularly in those over the age of 50, those who have higher body weight, and those with raised HbA1c and fasting plasma glucose levels.

Research Progress on the Relationship between Vitamins and Diabetes: Systematic Review

Diabetes is a serious chronic metabolic disease that causes complications over time, bringing serious public health challenges that affect different countries across the world. The current clinical drugs for diabetes may lead to adverse effects such as hypoglycemia and liver and abdominal distension and pain, which prompt people to explore new treatments for diabetes without side effects. The research objective of this review article is to systematically review studies on vitamins and diabetes and to explain their possible mechanism of action, as well as to assess the role of vitamins as drugs for the prevention and treatment of diabetes. To achieve our objective, we searched scientific databases in PubMed Central, Medline databases and Web of Science for articles, using "vitamin" and "diabetes" as key words. The results of numerous scientific investigations revealed that vitamin levels were decreased in humans and animals with diabetes, and vitamins show promise for the prevention and/or control of diabetes through anti-inflammation, antioxidation and the regulation of lipid metabolism. However, a few studies showed that vitamins had no positive effect on the development of diabetes. Currently, studies on vitamins in the treatment of diabetes are still very limited, and there are no clinical data to clarify the dose-effect relationship between vitamins and diabetes; therefore, vitamins are not recommended as routine drugs for the treatment of diabetes. However, we still emphasize the great potential of vitamins in the prevention and treatment of diabetes, and higher quality studies are needed in the future to reveal the role of vitamins in the development of diabetes.

Vitamin D deficiency and its associated factors among patients with type 2 diabetes mellitus: a systematic review and meta-analysis

OBJECTIVE

The study intended to assess the pooled prevalence of vitamin D deficiency (VDD) and its associated factors among patients with type 2 diabetes mellitus (T2DM).

DESIGN

The Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines were employed to plan and conduct this systematic review and meta-analysis.

DATA SOURCES

PubMed, Medline, Google Scholar, Web of Science, Science Direct and the Worldwide Science database were searched from their inception to 31 January 2023.

METHODS

Data were extracted using a standardised data extraction format prepared in Microsoft Excel. The inverse variance (I2) test was used to evaluate the presence of heterogeneity across the included studies. To identify the possible source of heterogeneity, subgroup analysis was carried out. Funnel plot symmetry, Begg's and Egger's tests were used to evaluate the existence of publication bias. In addition, factors associated with VDD among patients with T2DM were examined. All statistical analyses were carried out with STATA V.14 software.

RESULTS

A total of 54 studies with 38 016 study participants were included in the study. The pooled prevalence of VDD among patients with T2DM was found to be 64.2% (95% CI 60.6% to 67.8%) with a substantial level of heterogeneity (I2=98.2%; p<0.001). Results of the subgroup analysis indicated that the pooled prevalence of VDD among patients with T2DM was highest (70.9%) in African nations and lowest (57.1%) in Middle East countries. Being female (pooled OR (POR) 1.60, 95% CI 1.29 to 1.97), having poor glycaemic control (POR 2.50; 95% CI 1.74 to 3.59), hypertension (POR 1.21; 95% CI 1.08 to 1.36), obesity (body mass index ≥25) (POR 1.68; 95% CI 1.16 to 2.44), dyslipidaemia (POR 2.54, 95% CI 1.37 to 4.73), albuminuria (POR 2.22, 95% CI 1.71 to 2.95), nephropathy (POR 1.58; 95% CI 1.08 to 2.31) and retinopathy (POR 1.48: 95% CI 1.17 to 1.89) were predictors of VDD among patients with T2DM.

CONCLUSIONS

More than half of patients with T2DM were suffering from VDD. Being female, having poor glycaemic control, hypertension, obesity, dyslipidaemia, albuminuria, nephropathy and retinopathy were the predictors of VDD among patients with T2DM.

Immunomodulatory actions of vitamin D in various immune-related disorders: a comprehensive review

For many years, vitamin D has been acknowledged for its role in maintaining calcium and phosphate balance. However, in recent years, research has assessed its immunomodulatory role and come up with conflicting conclusions. Because the vitamin D receptor is expressed in a variety of immune cell types, study into the precise role of this molecule in diseases, notably autoimmune disorders, has been made possible. The physiologically activated version of vitamin D also promotes a tolerogenic immunological condition in addition to modulating innate and acquired immune cell responses. According to a number of recent studies, this important micronutrient plays a complex role in numerous biochemical pathways in the immune system and disorders that are associated with them. Research in this field is still relatively new, and some studies claim that patients with severe autoimmune illnesses frequently have vitamin D deficiencies or insufficiencies. This review seeks to clarify the most recent research on vitamin D's immune system-related roles, including the pathophysiology of major disorders.

Mechanisms Suggesting a Relationship between Vitamin D and Erectile Dysfunction: An Overview

Vitamin D deficiency (VDD) and erectile dysfunction (ED) heavily burden the male population. The higher prevalence of both conditions in the elderly suggests a possible relationship between the two conditions. In addition, in vitro, animal, and human studies have revealed several mechanisms that may relate VDD to ED. The main mechanism by which vitamin D might exert its action on sexual function appears to be through the regulation of endothelial function. Indeed, VDD correlates with several markers of endothelial function. The action of vitamin D on the endothelium would be exercised both indirectly through its intervention in inflammatory processes and through the production of oxygen free radicals, and directly through the regulation of vascular stiffness, the production of nitric oxide, and the regulation of vessel permeability. Furthermore, the ubiquitous distribution of the vitamin D receptor in the human body means that this hormone can also exert a beneficial effect on erectile function by interfering with those comorbidities significantly associated with ED, such as hypertension, diabetes mellitus, hypercholesterolemia, chronic kidney disease, and hypogonadism. In this review, we thoroughly and carefully presented the evidence and mechanisms that would appear to relate vitamin D levels to erectile function. Furthermore, we have summarized the meta-analytic evidence for and against this association to provide a true representation of this topic. Data published to date suggest that low levels of vitamin D could contribute to worsening erectile function through several mechanisms. Therefore, vitamin D levels should be measured in patients with ED and maintained at adequate levels by specific supplementation in case of deficiency. However, the low quality and heterogeneity of clinical trials evaluating the effects of vitamin D administration on erectile function and ED-associated comorbidities do not allow for a univocal conclusion, and indicate the need for further studies to analyze these aspects.

COVID-19 infection and metabolic comorbidities: Mitigating role of nutritional sufficiency and drug - nutraceutical combinations of vitamin D

The vulnerability of human health is amplified in recent times with global increase in non-communicable diseases (due to lifestyle changes and environmental insults) and infectious diseases (caused by newer pathogens and drug-resistance strains). Clinical management of diseases is further complicated by disease severity caused by other comorbid factors. Drug-based therapy may not be the sole approach, particularly in scenarios like the COVID-19 pandemic, where there is no specific drug against SARS-CoV-2. Nutritional interventions are significant in armouring human populations in disease prevention, and as adjunctive therapy for disease alleviation. Amidst ongoing clinical trials to determine the efficacy of Vit. D against infections and associated complications, this review examines the pleiotropic benefits of nutritional adequacy of vitamin D (Vit. D) in combating viral infections (COVID-19), its severity and complications due to co-morbidities (obesity, diabetes, stroke and Kawasaki disease), based on research findings and clinical studies. Supplements of Vit. D in combination with other nutrients, and drugs, are suggested as promising preventive-health and adjunct-treatment strategies in the clinical management of viral infections with metabolic comorbidities.

Genetic Variations of the Vitamin D Metabolic Pathway and COVID-19 Susceptibility and Severity: Current Understanding and Existing Evidence

The immunomodulatory and metabolic effects of vitamin D receptor (VDR) activation have been considered beneficial in mitigating the susceptibility and severity of COVID-19 infection. Furthermore, vitamin D-binding protein (DBP) has pleiotropic effects on the immune system that may influence inflammation associated with COVID-19. Multiple observational studies have demonstrated an association between low levels of serum 25-hydroxyvitamin D and risk and the severity of COVID-19 infection. However, the impact of vitamin D supplementation as an adjunctive treatment for COVID-19 based on evidence from randomized clinical trials is unclear. Equally important is that certain variations of the genes involved in the vitamin D metabolic pathway have been shown to affect immune function and linked with various clinical outcomes, including cardio-metabolic disorders, autoimmune diseases, infections, and cancers. This indicates inter-individual difference in body response to vitamin D. There is also emerging evidence that common polymorphisms of these genes may influence the susceptibility and severity of COVID-19, although the confidence of these findings is limited by a small number of studies and participants. Further studies are needed to address the potential role of VDR activation and DBP in the pathophysiology of COVID-19 which take into account the genetic variations of vitamin D metabolic pathway.

Vitamin D regulates insulin and ameliorates apoptosis and oxidative stress in pancreatic tissues of rats with streptozotocin-induced diabetes

This study was designed to evaluate the potential therapeutic efficacy of vitamin D (Vit D) in averting the harmful effects of type 2 diabetes mellitus (T2D). Forty male Wistar rats were allotted into four groups: (1) the control, (2) Vit D, (3) streptozotocin (STZ), and (4) STZ + Vit D groups. Rats co-treated with Vit D had significantly (p < 0.05) decreased levels of cortisol; proinflammatory cytokines, including interleukin-6 (IL-6); and malondialdehyde (MDA). Meanwhile, the levels of insulin significantly (p < 0.05) increased, whereas the activity of the antioxidant system, including glutathione (GSH), superoxide dismutase (SOD), catalase, and total antioxidant capacity (TAC), significantly (p < 0.05) decreased. Histopathological examination revealed the destruction of beta cells in the islets of Langerhans in rats with diabetes. Meanwhile, immunoexpression revealed an increase in the immunoreactivity of caspase-3 and endothelial nitric oxide synthase and a reduction in the immunoreactivity of insulin in rats with diabetes. In conclusion, Vit D ameliorated the harmful biochemical impact of diabetes mellitus, probably by increasing insulin secretion and sensitivity, ameliorating β-cell function, and decreasing cortisol levels; also, the anti-inflammatory effect of Vit D reduces the number of proinflammatory cytokines (e.g., IL-6) and increases the activity of the antioxidant system, such as GSH, SOD, TAC, and catalase while reducing lipid peroxidation enzymes (e.g., MDA).

The Role of Dietary Intake in Type 2 Diabetes Mellitus: Importance of Macro and Micronutrients in Glucose Homeostasis

The prevalence of Type 2 diabetes (T2D) is increasing worldwide. Genetics and lifestyle, especially diet, are contributing factors. Analyses of macro- and micronutrient intake across global populations may help to explain their impact on glucose homeostasis and disease development. To this end, 420 Tunisians were enrolled in a prospective cross-sectional study of daily food consumption. Various data were collected and blood samples were drawn for biochemical assay. A 24-h recall questionnaire was obtained from participants to evaluate dietary intake. Statistical analyses were conducted using Nutrilog and R software. Biochemical analyses stratified the studied population (n = 371) into three groups: diabetics (n = 106), prediabetics (n = 192) and controls (n = 73); 49 subjects were excluded. Our results showed that Tunisians had hypercaloric diets high in carbohydrates and fat with variability in the levels of some vitamins and minerals, including riboflavin and niacin, that were statistically different among groups. The lower intake of vitamin D was associated with a greater risk of T2D. Higher vitamin A and sodium intake were associated with poor glucose homeostasis, although protein intake may improve it. In perspective, nutrigenomic studies can provide insight into problematic diets and poor eating habits and offer opportunities to analyze the effects of behavioral changes that can mitigate T2D development and progression.

Combined exposure to fine particulate matter and high glucose aggravates endothelial damage by increasing inflammation and mitophagy: the involvement of vitamin D

Background

Cardiovascular diseases (CVDs) are related to particulate matter (PM_2.5) exposure. Researchers have not clearly determined whether hyperglycemia, a hallmark of diabetes, exacerbates PM_2.5-induced endothelial damage. Thus, this study aimed to investigate the combined effects of PM_2.5 and high glucose on endothelial damage.

Results

Here, we treated human umbilical vein endothelial cells (HUVECs) with 30 mM high glucose and 50 μg/mL PM (HG + PM) to simulate endothelial cells exposed to hyperglycemia and air pollution. First, we showed that HUVECs exposed to PM under high glucose conditions exhibited significant increases in cell damage and apoptosis compared with HUVECs exposed to PM or HG alone. In addition, PM significantly increased the production of reactive oxygen species (ROS) in HUVECs and mitochondria treated with HG and decreased the expression of superoxide dismutase 1 (SOD1), a free radical scavenging enzyme. The coexposure group exhibited significantly increased ROS production in cells and mitochondria, a lower mitochondrial membrane potential, and increased levels of the autophagy-related proteins p62, microtubule-associated protein 1 light chain 3β (LC3B), and mitophagy-related protein BCL2 interacting protein 3 (Bnip3). Moreover, autophagosome-like structures were observed in the HG + PM group using transmission electron microscopy. The expression of intercellular adhesion molecule-1 (ICAM-1) and vascular cell adhesion molecule-1 (VCAM-1) were also increased through the JNK/p38 signaling pathway in the HG + PM group. As a ROS scavenger, vitamin D treatment effectively protected cells under HG and PM conditions by increasing cell viability, reducing mitochondrial ROS production, and suppressing the formation of mitophagy and inflammation. Furthermore, diabetes was induced in mice by administering streptozotocin (STZ). Mice were treated with PM by intratracheal injection. Vitamin D effectively alleviated oxidative stress, mitophagy, and inflammation in the aortas of mice treated with STZ and PM.

Conclusion

Taken together, simultaneous exposure to PM and high glucose exerts significant harmful effects on endothelial cells by inducing ROS production, mitophagy, and inflammation, while vitamin D reverses these effects.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12989-022-00462-1.

Vitamin D deficiency associated with risk of prediabetes among older adults: Data from the National Health and Nutrition Examination Survey (NHANES), 2007-2012

AIM

To examine the association between vitamin D (25(OH)D) deficiency and risk of prediabetes in Americans 50+ years of age.

MATERIALS AND METHODS

This was a cross-sectional analysis of NHANES (2007-2012) subjects aged 50+ years, free of kidney/liver diseases and diabetes. Prediabetes was defined as: HbA1c level 5.7%-6.4%, or fasting plasma glucose level 100-125 mg/dL, or Oral Glucose Tolerance Test result 140-199 mg/dL, with no laboratory value in the diabetic range. The comparison group had normal glucose tolerance (NGT) with no marker in the prediabetes/diabetes range. Total serum 25(OH)D levels were deficient at <50 nmol/L, insufficient 50-75 nmol/L, and sufficient >75 nmol/L. Logistic regression included strata, cluster and weight variables. Models were adjusted for body mass index (BMI), ethnicity, age and gender.

RESULTS

The final sample was 2286 adults, predominantly White (80.4%) and female (56.6%), with a mean age of 62.3 years. Within the sample, 1387 had prediabetes (59.1%) and 899 were NGT (40.9%). Individuals classified within a lower serum vitamin D category were more likely to have prediabetes (p = 0.03). Those with 25(OH)D deficiency were more likely to have prediabetes compared to 25(OH)D sufficient individuals (crude OR = 1.48, 95% CI 1.15-1.91), and this association remained significant after adjustment for ethnicity, BMI, age and gender (aOR = 1.39, 95% CI 1.02-1.89). There was no effect modification by BMI, gender or ethnicity.

CONCLUSIONS

Vitamin D status was associated with risk of prediabetes in this sample of Americans 50+ years of age. Future research should seek to understand the potential mechanistic relationship between vitamin D and prediabetes.

Vitamin D Deficiency Is Associated with Glycometabolic Changes in Nondiabetic Patients with Arterial Hypertension

Recent evidence indicates that mildly increased fasting and post-oral load blood glucose concentrations contribute to development of organ damage in nondiabetic patients with hypertension. In previous studies, vitamin D deficiency was associated with decreased glucose tolerance. The aim of this study was to examine the relationships between serum 25(OH)D levels and glucose tolerance and insulin sensitivity in hypertension. In 187 nondiabetic essential hypertensive patients free of cardiovascular or renal complications, we measured serum 25-hydroxyvitamin D (25(OH)D) and parathyroid hormone (PTH) and performed a standard oral glucose tolerance test (OGTT). Patients with 25(OH)D deficiency/insufficiency were older and had significantly higher blood pressure, fasting and post-OGTT (G-AUC) glucose levels, post-OGTT insulin (I-AUC), PTH levels, and prevalence of metabolic syndrome than patients with normal serum 25(OH)D. 25(OH)D levels were inversely correlated with age, blood pressure, fasting glucose, G-AUC, triglycerides, and serum calcium and PTH, while no significant relationships were found with body mass index (BMI), fasting insulin, I-AUC, HOMA index, and renal function. In a multivariate regression model, greater G-AUC was associated with lower 25(OH)D levels independently of BMI and seasonal vitamin D variations. Thus, in nondiabetic hypertensive patients, 25(OH)D deficiency/insufficiency could contribute to impaired glucose tolerance without directly affecting insulin sensitivity.

Vitamin D and Omega-3 Polyunsaturated Fatty Acids in Type 1 Diabetes modulation

BACKGROUND

Type 1 diabetes (T1D) is a chronic autoimmune disease that affects people globally. Usually developed during childhood, T1D is characterized by the destruction of pancreatic β-cells due to immune cell attack and the establishment of an inflammatory process.

OBJECTIVE

The study aimed to investigate the effects of vitamin D through its nuclear receptor and the ω-3 polyunsaturated fatty acids (PUFAs) through their lipid derivatives in T1D modulation. Both components exert anti-inflammatory activity and act directly on cells of the immune system, attenuating the destruction of insulin-producing cells. Furthermore, they lead to a better glycemic level, reducing the need for insulin and a normal immune state, such as C-peptide maintenance.

METHOD

Presently, our review highlights the significant studies that evaluated the supplementation of vitamin D and ω-3 PUFAs in humans and animal models in the modulation of T1D.

CONCLUSION

The data collected suggests that supplementation can provide potential benefits, mainly when done early in the diagnosis, since it reduces the need for insulin and the risk of complications generated by the disease.

Vitamin D3 deficiency is associated with more severe insulin resistance and metformin use in patients with type 2 diabetes

BACKGROUND

Vitamin D3 (vit. D3) deficiency is considered as one of the main factors involved in the development of type 2 diabetes (T2D). We assessed insulin resistance (IR), β-cell functional activity and metabolic profile according to 25(OH) vit. D3 status in patients with T2D.

METHODS

The study included 109 patients with T2D, divided in 3 groups: group 1 (N.=11) with normal levels of vit. D3 (>30 ng/mL); group 2 (N.=38) with vit. D3 insufficiency (21-29 ng/mL); and group 3 (N.=60) with vit. D3 deficiency (<20 ng/mL). IR and β-cell functional activity were assessed as change in C-peptide concentration and homeostasis model assessment-estimated (HOMA) β-cell function which was calculated using HOMA2 calculator.

RESULTS

Patients with vit. D3 deficiency presented significantly higher C-peptide concentration compared to other groups. HOMA2 (3.29±1.89 vs. 2.12±0.71; P=0.049) and hemoglobin (H8b)A1c (9.11±1.63 vs. 7.75±1.06; P=0.016) levels changed significantly only in patients with vit. D3 deficiency compared to diabetics with normal vit. D3 levels. Furthermore, in univariate Pearson's correlation analysis, we observed significant association between vit. D3 levels and C-peptide, insulin sensitivity, HOMA2, triglyceride-glucose index, HbA1c and Body Mass Index, only in the vit. D3 deficiency group. In multivariate logistic regression analysis, poor glycemic control, as defined by HbA1c levels, was independent from metformin use while high density lipoprotein-cholesterol levels were associated with vit. D3 deficiency.

CONCLUSIONS

Our study demonstrated that vit. D3 deficiency in patients with T2D was associated with more severe IR, poor glycemic control and obesity compared to normal status or vit. D3 insufficiency.

Vitamin D, Calcium Supplements, and Implications for Cardiovascular Health: JACC Focus Seminar

Vitamin D and calcium supplements are commonly used, often together, to optimize bone health. Multiple observational studies have linked low serum 25-hydroxyvitamin D concentrations with increased cardiovascular risk. However, subsequent randomized controlled trials (RCTs) failed to demonstrate cardiovascular benefit with vitamin D supplementation. Although vitamin D supplements do not appear to be harmful for cardiovascular health, the lack of benefit in RCTs should discourage their use for this purpose, favoring optimizing vitamin D status through healthy lifestyles such as specific foods and modest sunlight exposure. Furthermore, some (but not all) observational and RCT studies of calcium supplementation have suggested potential for cardiovascular harm. Therefore, calcium supplementation should be used cautiously, striving for recommended intake of calcium predominantly from food sources. In this review, the authors examine the currently available evidence investigating whether vitamin D and calcium supplements are helpful, harmful, or neutral for cardiovascular health.

Management of bone fragility in type 2 diabetes: Perspective from an interdisciplinary expert panel

AIM

Bone fragility is increasingly recognized as a relevant complication of type 2 diabetes (T2D) and diabetic patients with fragility fractures have higher mortality rates than non diabetic individuals or diabetic patients without fractures. However, current diagnostic approaches for fracture risk stratification, such as bone mineral density measurement or the use of risk assessment algorithms, largely underestimate fracture risk in T2D patients. A multidisciplinary expert panel was established in order to in order to formulate clinical consensus recommendations on bone health assessment and management of fracture risk in patients with T2D.

DATA SYNTHESIS

The following key questions were addressed: a) which are the risk factors for bone fragility in T2D?, b) which diagnostic procedures can be currently used to stratify fracture risk in T2D patients?, c) which are the effects of antidiabetic treatments on bone?, and d) how to prevent and treat bone fragility in T2D patients? Based on the available data members of this panel suggest that the stratification of fracture risk in patients with diabetes should firstly rely on the presence of a previous fragility fracture and on the individual risk profile, with the inclusion of T2D-specific risk factors (namely T2D duration above 10 yrs, presence of chronic T2D complications, use of insulin or thiazolidinediones and persistent HbA1c levels above 8% for at least 1 year). Two independent diagnostic approaches were then suggested in the presence or the absence of a prevalent fragility fracture, respectively.

CONCLUSIONS

Clinical trials in T2D patients at risk for fragility fractures are needed to determine the efficacy and safety of available antiresorptive and anabolic agents in this specific setting.

Vitamin D Deficiency and Risk of Metabolic Syndrome in Aging Men

The elderly population is rapidly increasing; hence, the disability due to age-related diseases has become an important socioeconomic burden. Amongst age-related diseases cardiovascular ones (CVD) have a huge impact on morbidity and mortality and are associated with metabolic syndrome (MetS). Several studies investigated the role of hypovitaminosis D in the pathogenesis of MetS and of CVD, this review unravels the relationship between aging/senescence, vitamin D, gender, and pathogenesis of MetS.

Effect of 1-year oral cholecalciferol on a metabolic profile and blood pressure in poor-controlled type 2 diabetes mellitus: an open-label randomized controlled pilot study

PURPOSE

Hypovitaminosis D has been associated with many cardio-metabolic disorders, although their pathogenetic link still remains unclear. Our aim was to evaluate whether 1-year vitamin D (D) supplementation could improve glycemic control, lipid profile, systolic (SBP) and diastolic (DBP) blood pressure levels and body composition.

METHODS

In an open-label randomized-controlled pilot study, thirty poor-controlled (HbA1c > 59 mmol/mol) type 2 diabetic patients (age 71.5 ± 3.2 years, M/F 21/9, BMI 29.8 ± 3.6 kg/m²) with hypovitaminosis D (25OHD 22.0 ± 11.3 nmol/l) were randomized to cholecalciferol supplementation (500 UI/kg p.o. weekly, + D) or observation (- D) for one year. Changes in parameters of glucose, lipid and blood pressure control at 3, 6, 9 and 12 months vs. baseline were assessed.

RESULTS

One-year D supplementation restored D status and had a beneficial effect on fasting glucose (FG, mean percentage changes ± SD, - 1.8% ± 23.1 vs. + 18.8% ± 30.0), glycosylated haemoglobin (HbA1c, - 13.7% ± 14.5 vs. - 4.2% ± 14.1), SBP (- 13.4% ± 8.5 vs. - 2.4% ± 12.6) and HDL-cholesterol levels (- 2.1% ± 14.0 vs. - 10.9% ± 12.9; p < 0.05 for all comparisons) in + D vs. - D patients, respectively. In the former, a reduction in HBA1c, SBP and DBP levels, BMI, fat mass index (FMI) and ratio (FMR) was observed after 1 year (p < 0.05 for all comparisons vs. baseline). We noticed a relationship between 1-year mean percentage changes of serum 25OHD and SBP levels (R = - 0.36, p < 0.05).

CONCLUSION

One-year cholecalciferol supplementation, able to restore D status, significantly improves FG, HbA1c, SBP and HDL-cholesterol levels in patients with poor-controlled type 2 diabetes mellitus and D deficiency.

Vitamin D and cardiovascular health

The principal source of vitamin D in humans is its biosynthesis in the skin through a chemical reaction dependent on sun exposure. In lesser amounts, the vitamin can be obtained from the diet, mostly from fatty fish, fish liver oil and mushrooms. Individuals with vitamin D deficiency, defined as a serum level of 25 hydroxyvitamin D < 20 ng/dl, should be supplemented. Vitamin D deficiency is a prevalent global problem caused mainly by low exposure to sunlight. The main role of 1,25 dihydroxyvitamin D is the maintenance of calcium and phosphorus homeostasis. However, vitamin D receptors are found in most human cells and tissues, indicating many extra-skeletal effects of the vitamin, particularly in the immune and cardiovascular (CV) systems. Vitamin D regulates blood pressure by acting on endothelial cells and smooth muscle cells. Its deficiency has been associated with various CV risk factors and appears to be linked to a higher mortality and incidence of CV disease (CVD). Several mechanisms have been proposed relating vitamin D deficiency to CV risk factors such as renin-angiotensin-aldosterone system activation, abnormal nitric oxide regulation, oxidative stress or altered inflammatory pathways. However, in the latest randomized controlled trials no benefits of vitamin D supplementation for CVD have been confirmed. Although more work is needed to establish the protective role of vitamin D in this setting, according to current evidences vitamin D supplements should not be recommended for CVD prevention.

Involvement of TGF-β and Autophagy Pathways in Pathogenesis of Diabetes: A Comprehensive Review on Biological and Pharmacological Insights

Despite recent advancements in clinical drugs, diabetes treatment still needs further progress. As such, ongoing research has attempted to determine the precise molecular mechanisms of the disorder. Specifically, evidence supports that several signaling pathways play pivotal roles in the development of diabetes. However, the exact molecular mechanisms of diabetes still need to be explored. This study examines exciting new hallmarks for the strict involvement of autophagy and TGF-β signaling pathways in the pathogenesis of diabetes and the design of novel therapeutic strategies. Dysregulated autophagy in pancreatic β cells due to hyperglycemia, oxidative stress, and inflammation is associated with diabetes and accompanied by dysregulated autophagy in insulin target tissues and the progression of diabetic complications. Consequently, several therapeutic agents such as adiponectin, ezetimibe, GABA tea, geniposide, liraglutide, guava extract, and vitamin D were shown to inhibit diabetes and its complications through modulation of the autophagy pathway. Another pathway, TGF-β signaling pathway, appears to play a part in the progression of diabetes, insulin resistance, and autoimmunity in both type 1 and 2 diabetes and complications in diabetes. Subsequently, drugs that target TGF-β signaling, especially naturally derived ones such as resveratrol, puerarin, curcumin, hesperidin, and silymarin, as well as Propolis, Lycopus lucidus, and Momordica charantia extracts, may become promising alternatives to current drugs in diabetes treatment. This review provides keen insights into novel therapeutic strategies for the medical care of diabetes.

Vitamin D Receptor Overexpression in β-Cells Ameliorates Diabetes in Mice

Vitamin D deficiency has been associated with increased incidence of diabetes, both in humans and in animal models. In addition, an association between vitamin D receptor (VDR) gene polymorphisms and diabetes has also been described. However, the involvement of VDR in the development of diabetes, specifically in pancreatic β-cells, has not been elucidated yet. Here, we aimed to study the role of VDR in β-cells in the pathophysiology of diabetes. Our results indicate that Vdr expression was modulated by glucose in healthy islets and decreased in islets from both type 1 diabetes and type 2 diabetes mouse models. In addition, transgenic mice overexpressing VDR in β-cells were protected against streptozotocin-induced diabetes and presented a preserved β-cell mass and a reduction in islet inflammation. Altogether, these results suggest that sustained VDR levels in β-cells may preserve β-cell mass and β-cell function and protect against diabetes.

Anti-tuberculous Effects of Statin Therapy: A Review of Literature

Tuberculosis (TB) is a chronic infection caused by Mycobacterium tuberculosis (M. TB). It is transmitted through respiratory droplets. Increased cholesterol level is a predisposing factor for TB. M. TB uses cholesterol in the host macrophage membranes to bind and enter the macrophages. Statins are the drugs that are prescribed to hyperlipidemic patients to maintain their lipid levels in the normal range, thereby reducing the risk of stroke and cardiovascular events. Moreover, statins aid in reducing the levels of cholesterol in human macrophages. Therefore, a reduction in the membrane cholesterol minimizes the entry of TB pathogen inside macrophages. Furthermore, acting as vitamin D3 analogs and positively influencing pancreatic beta-cell function in a chronic diabetic state, statins minimize the occurrence of M. TB infection among diabetic population as well. This review aims to provide a comprehensive detail of all in vitro, in vivo, and retrospective studies that investigated the effects of statins in relation to the prevention or treatment of TB infection.

A Potential Linking between Vitamin D and Adipose Metabolic Disorders

Vitamin D has been discovered centuries ago, and current studies have focused on the biological effects of vitamin D on adipogenesis. Besides its role in calcium homeostasis and energy metabolism, vitamin D is also involved in the regulation of development and process of metabolic disorders. Adipose tissue is a major storage depot of vitamin D. This review summarized studies on the relationship between vitamin D and adipogenesis and furthermore focuses on adipose metabolic disorders. We reviewed the biological roles and functionalities of vitamin D, the correlation between vitamin D and adipose tissue, the effect of vitamin D on adipogenesis, and adipose metabolic diseases. Vitamin D is associated with adipogenesis, and vitamin D supplements can reduce the burden caused by metabolic diseases. The review provides new insights and basis for medical therapy on adipose metabolic diseases.

The effect of daily consumption of different doses of fortified Lavash bread versus plain bread on serum vitamin-D status, body composition, metabolic and inflammatory biomarkers, and gut microbiota in apparently healthy adult: study protocol of a randomized clinical trial

BACKGROUND

Due to the high prevalence of vitamin-D deficiency worldwide and its health consequences, intervention studies at the community level are warranted. The present study has been conducted to evaluate the effectiveness of vitamin-D-fortified bread on serum vitamin-D levels, inflammatory and metabolic biomarkers, and gut microbiota composition in vitamin-D-deficient individuals.

METHODS/DESIGN

A double-blind, randomized controlled clinical trial is conducted on apparently healthy individuals with vitamin-D deficiency. The random allocation is done to divide participants into intervention groups including daily intake of vitamin-D-3-fortified bread (FB) with 500 IU/100 g bread (n = 30), FB with 1000 IU/100 g bread (n = 30), and 100 g plain bread (PD) (n = 30). At baseline and after 3 months of the intervention period, blood, stool, and urine samples are taken. Anthropometric measures, body composition, blood pressure, and dietary assessment are made. The gut microbiome composition is measured by the 16S rRNA approach. Data is analyzed by SPSS software version 21.

DISCUSSION

This study may partly explain for the first time the conflicting results from recent critical and systematic reviews regarding the role of vitamin D in microbiota composition.

TRIAL REGISTRATION

Iranian Registry of Clinical Trials (IRCT), ID: IRCT20170812035642N3. Registered on 11 March 2018; http://www.irct.ir/user/trial/28134/view.

The optimal vitamin D cut-off value associated with hyperglycemia in an Iranian population

Background

Vitamin D deficiency may accelerate the risk of type 2 diabetes mellitus. The association of vitamin D with hyperglycemia may be influenced by lifestyle.

Objective

To evaluate the relationship between vitamin D status and hyperglycemia among the workers' population.

Methods

This was a medical records review of 7054 Iranian factory workers participating in an annual health check-up for employees. Of those, potential participants were included in this analysis if data for serum 25-hydroxyvitamin D [25(OH) D] levels were also available.

Results

Data of 429 male participants were used for this analysis. Of those, 61.07% had serum 25(OH)D concentrations lower than the sufficient level [≥20 ng/ml]. Hyperglycemic participants had significantly lower 25(OH)D than those with normal fasting blood glucose (FBG). Regression analyses highlighted serum 25(OH)D as a significant determinant of hyperglycemia [OR: 0.943(0.901, 988); p = 0.01]. The association between 25(OH)D and FBG remained significant after adjustment for potential confounders (p = 0.008). Using the ROC analysis, the serum 25(OH)D value of 14.7 ng/ml was the optimal cut-off point to predict hyperglycemia in this population (sensitivity: 63.6%, specificity: 62.3%, p = 0.01).

Conclusion

Our results revealed a considerable proportion of participants with serum 25(OH)D below the optimal level as well as a significant inverse association between vitamin D status and hyperglycemia among the factory workers. These findings highlight the importance of including the evaluation of vitamin D status as a part of annual health examinations for employees, and may help health policy- makers prevent or delay type 2 diabetes mellitus among the workers' population.

Low vitamin D is associated with diabetes peripheral neuropathy in older but not in young and middle-aged patients

BACKGROUND

The relationship between vitamin D and diabetes peripheral neuropathy (DPN) is not consistent among epidemiologic studies. Thus, we aimed to investigate this relationship in different age groups.

METHODS

In this cross-sectional study, 1461 patients admitted to the Department of Endocrinology at Xinhua Hospital from June 2016 to September 2017 were divided into three age groups: a Youth group (24-44 years, n = 127), a Middle-age group (45-64 years, n = 779), and an Elderly group (≥65 years, n = 555). Basic information and laboratory results were collected from medical records.

RESULTS

Among the patients, 32.72% had DPN, with 12.59% in the Youth group, 33.63% in the Middle-age group, and 36.04% in the Elderly group. For the total sample and the Elderly group, serum 25(OH)D concentrations in DPN patients were lower than in non-DPN patients (P < .05). The results of multivariate logistic regression indicated a low vitamin D concentration to be a risk factor for DPN in the Elderly group (P < .05), but such relationship was not found in the Youth or Middle-age groups. Moreover, according to ROC analysis, a serum 25(OH)D level < 34.87 nmol/L suggests the occurrence of DPN in elderly patients with type 2 diabetes (P < .001).

CONCLUSIONS

This study is the first to report that a low vitamin D level is associated with DPN in diabetic patients over 65 years of age and might be used as a predictor of DPN in this population. The interaction between vitamin D and age in the development of DPN and its underlying mechanisms need to be further explored.

Serum vitamin D status in type 2 diabetic patients from Gaza Strip

OBJECTIVE

To assess serum vitamin D status and its relations to other biochemical parameters in type 2 diabetic patients from Gaza Strip.

MATERIALS AND METHODS

This case-control study included 58 type 2 diabetic patients as well as 58 non-diabetic controls. Patients and controls were matched for age and gender. Data were obtained from questionnaire interview, and biochemical analysis of blood samples.

RESULTS

Serum vitamin D was significantly lower in diabetic patients compared to non-diabetic controls (25.9 ± 11.0 versus 34.6 ± 13.8 ng/dl, % difference = 28.8%, P < 0.001). The number of patients having vitamin D deficient, insufficient and sufficient were 6 (10.4%), 35 (60.3%) and 17 (29.3%) compared to controls of 3 (5.2%), 16 (27.6%) and 39 (67.2%), respectively (χ² = 14.672, P < 0.001). Serum glucose, glycated hemoglobin (HbA1c), serum alanine aminotransferase (ALT), aspartate aminotransferase (AST) and triglycerides were significantly higher in patients than in controls whereas serum insulin, high density lipoprotein cholesterol (HDL-C) and calcium were significantly lower in patients. Serum vitamin D showed significant negative correlations with HbA1c (r = - 0.186, P = 0.046), ALT (r = - 192, P = 0.040) and AST (r = - 0.188, P = 0.044) whereas significant positive correlations were found with HDL-C (r = 0.188, P = 0.044) and calcium (r = 0.239, P = 0.010).

CONCLUSION

The significant negative and positive correlations of vitamin D with HbA1c and calcium, respectively suggests that vitamin D supplementation would be of potential therapeutic value in clinical settings for controlling of type 2 diabetes and more importantly its complications. However, a well-designed clinical trials are needed to define the contribution of vitamin D status and therapy in the global diabetes problem.

Vitamin D status of Turkish type 1 diabetic patients

INTRODUCTION

Vitamin D was associated with the pathogenesis, treatment and prognosis of type 1 and type 2 diabetes mellitus. The aim of this study is to assess vitamin D status of Turkish adult type 1 DM patients and compare them with health controls and also to assess the relationship of vitamin D and glycemic control.

METHOD

Study was designed as cross-sectional and conducted in a tertiary Hospital diabetes unit. 296 type diabetic patients and 151 healthy controls was included to the study. Venous samples were collected into plain tubes after overnight fasting. Serum 25-hydroxyvitamin D level was measured by radioimmunoassay technique. Statistical analysis was performed with SPSS 15.0.

RESULTS

25-Hydroxyvitamin D levels were similar between patients with type 1 diabetes (22, 9 ± 17, 4 ng/ml) and controls (24, 5 ± 19, 3 ng/ml) (p = 0,382). Most of the participants have 25-Hydroxyvitamin D deficiency. As shown in Table 2 serum 25-Hydroxyvitamin D level was not associated with most of the biochemical or anthropometric parameters.

CONCLUSION

As a result there were no difference between type 1 diabetics and healthy controls according to their vitamin D levels. Further studies with a larger sample of patients will improve our understanding of the relation of vitamin D and diabetes.

Vitamin D3 supplementation improves serum SFRP5 and Wnt5a levels in patients with type 2 diabetes: A randomized, double-blind, placebo-controlled trial

Objective: To explore the effect of vitamin D3 on novel serum adipokines, secreted frizzled-related protein 5 (SFRP5) and Wingless-Type MMTV Integration Site Family Member 5a (Wnt5a) levels in Type 2 Diabetes Mellitus (T2DM) patients. Methods: Forty patients (16 women and 24 men) with type 2 diabetes participated in this double-blind, randomized, placebo-controlled clinical trial study. Participants were randomly assigned to receive 4000 IU vitamin D₃ (n = 20) or placebo (n = 20) daily for 2 months. Anthropometric indices, fasting blood glucose (FBS), hemoglobin A1c (HbA1c), insulin, serum tumor necrosis factor (TNF)-α, Wnt5a, SFRP5, physical activity, lipid profile, dietary intake, and serum calcidiol were assessed at the baseline and after 8 weeks. Results: In the group receiving Vitamin D, a significant increase in Calicidiol (15.03 ± 10.44 vs. 27.33 ± 11.2 ng/dl; P = < 0.001), SFRP5 (3.6 ± 0.46 vs. 3.98 ± 0.59 ng/ml; P = 0.01), and Wnt5a (0.33 ± 0.129 vs. 0.29 ± 0.047; P = 0.03) was observed. After two months supplementation, there were significant between-group differences in Calicidiol (27.33 ± 11.2 vs. 17.9 ± 12.95 ng/dl; P = 0.01), TNF-α (89.22 ± 34.28 vs. 164.93 ± 120.45 ng/ml; P = 0.006), Wnt5a (0.29 ± 0.047 vs. 0.33 ± 0.09; P = 0.04), and HbA1c (6.6 ± 0.96 % vs. 7.64 ± 1.15 %; p = 0.002). Moreover, the net changes (end - baseline) of Calicidiol (P = < 0.001), SFRP5 (P = 0.04), Wnt5a (P = 0.005), TNF-α (P = 0.01), insulin (P = 0.03), and QUICKI (P = 0.01) was significant between the groups. There were no significant effects on FBS and homeostasis model of assessment-estimated insulin resistance (HOMA-IR). Conclusion: 8 weeks of vitamin D3 supplementation for patients with type 2 diabetes may increase serum anti-inflammatory adipokine SFRP5 but decrease serum pro-inflammatory Wnt5a and TNF-α.

When and How to Diagnose and Treat Vitamin D Deficiency in Adults: A Practical and Clinical Update

Vitamin D deficiency is considered a major public health concern. Inadequate sun exposure, limited oral intake, and impaired intestinal absorption are common risk factors for vitamin D deficiency. An increasing amount of research is aimed at answering questions regarding the most convenient test that can assess vitamin D status, the indications for screening, and finally the utility of treatments for vitamin D deficiency. Our review outlines practical strategies to diagnose and treat vitamin D deficiency in adults. This study was undertaken in the PubMed and the Google Scholar databases in April 2018 without limitation as to the publication period. Vitamin D status is determined by measuring the 25-hydroxyvitamin D serum concentration. However, this technique has several limitations. Determining the accurate thresholds for vitamin D deficiency is still a matter of debate. Only individuals at risk for vitamin D deficiency should be screened. The symptoms of vitamin D deficiency are unspecific and very common. Therefore, physicians may easily suspect vitamin D deficiency, measure 25-hydroxyvitamin D levels, and sometimes overprescribe supplementation. Hypovitaminosis D could rarely be treated by increasing consumption of foods naturally containing and fortified with vitamin D. Special attention should be given to vitamin D supplementation to prevent adverse effects. No safe and well-defined threshold of ultraviolet exposure allows adequate vitamin D synthesis without increasing the risk of skin cancer. Unanimous and decisive guidelines are urgently needed to improve knowledge and practices related to vitamin D deficiency.

The association between 25-hydroxy vitamin D deficiency and diabetic complications in patients with type 2 diabetes mellitus

AIMS

To evaluation the relationship between serum 25-hydroxy vitamin D [25-(OH)D] deficiency and diabetic complications in patients with type 2 diabetes (T2DM).

METHODS

One hundred and sixty three patients with T2DM [DM + uncomplicated (n = 36), DM + nephropathy (n = 31), DM + neuropathy (n = 30), DM + retinopathy (n = 30), DM + cardiovascular disease (CAD) (n = 36)], 35 CAD and 40 healthy volunteers were included.

RESULTS

Serum 25-(OH)D levels were found as significantly lower in all patients compared to the control group (p < 0.05). 25-(OH)D in patients with DM + retinopathy (p < 0.006), DM + nephropathy (p < 0.001) and DM + neuropathy (p < 0.001) was significantly lower than that of the control group. 25-(OH)D in patients with DM + nephropathy (p < 0.001), DM + neuropathy (p < 0.01) and DM + retinopathy (p < 0.001) was significantly lower than in the DM + uncomplicated group. 25-(OH)D levels were found as significantly lower in DM + CAD compared to the CAD group (p < 0.01). Serum 25-(OH)D and HbA1c and parathyroid hormone (PTH) were found to be negatively correlated with each other in DM + all complications.

CONCLUSIONS

Low serum 25-OHD levels were found to be associated with the development of diabetes and complications. Low serum 25-OHD levels may be a consequence of even worse metabolic control of diabetes.

Vitamin D status in diabetic children and adolescents

INTRODUCTION

Besides its role in calcium homeostasis, vitamin D (VD) has an important immuno-mudulation effect. However, its role in autoimmune diseases such as type 1 diabetes is under discussion. This study designed to investigate serum VD status in children and adolescents with and without diabetes.

MATERIALS AND METHODS

In a case-control study, 85 diabetic and 85 non-diabetic control (total 170) aged 1-15 yr. were enrolled. History of breast feeding and vitamin supplementation was obtained; growth indices and serum levels of Calcium, phosphorous, Alkaline-Phosphatase (ALP), Hemoglobin-A1c and VD were measured and analyzed.

RESULTS

The mean values for VD in case and control groups were 12.80 ± 10.59 and 15.85 ± 9.92 nmol/L, respectively (p = 0.057). Serum VD status in these two groups was sufficient in 5.88% and 9.41%, insufficient in 18% and 14%, and deficient in 75.29% and 76.74%, respectively. Compared to the controls, diabetics had more history of breast-feeding (62.35% vs. 42.35%; p = 0.017) and higher serum ALP levels (772.34 ± 309.89 vs. 657.99 ± 395.11 U/L; p = 0.032).

CONCLUSION

More frequency of breast-feeding, higher serum ALP and mildly lower serum level of VD in diabetics suggests a significant difference in VD status in diabetics compared to the healthy peers indicating a potential role of this deficiency in the disease process.

Winter Cholecalciferol Supplementation at 51°N Has No Effect on Markers of Cardiometabolic Risk in Healthy Adolescents Aged 14-18 Years

Background

Epidemiologic studies have supported inverse associations between low serum 25-hydroxyvitamin D [25(OH)D] and cardiometabolic risk markers, but few randomized trials have investigated the effect of vitamin D supplementation on these markers in adolescents.

Objective

The objective of this study was to investigate the effect of winter-time cholecalciferol (vitamin D3) supplementation on cardiometabolic risk markers in white, healthy 14- to 18-y-old adolescents in the UK (51°N) as part of the ODIN Project.

Methods

In a dose-response trial, 110 adolescents (mean ± SD age: 15.9 ± 1.4 y; 43% male; 81% normal weight) were randomly assigned to receive 0, 10 or 20 μg/d vitamin D3 for 20 wk (October-March). Cardiometabolic risk markers including BMI-for-age z score (BMIz), waist circumference, systolic and diastolic blood pressure, fasting plasma triglycerides, cholesterol (total, HDL, LDL, and total:HDL), and glucose were measured at baseline and endpoint as secondary outcomes, together with serum 25(OH)D. Intervention effects were evaluated in linear regression models as between-group differences at endpoint, adjusted for the baseline value of the outcome variable and additionally for age, sex, Tanner stage, BMIz, and baseline serum 25(OH)D.

Results

Mean ± SD baseline serum 25(OH)D was 49.1 ± 12.3 nmol/L and differed between groups at endpoint with concentrations of 30.7 ± 8.6, 56.6 ± 12.4, and 63.9 ± 10.6 nmol/L in the 0, 10, and 20 μg/d groups, respectively (P ≤ 0.001). Vitamin D3 supplementation had no effect on any of the cardiometabolic risk markers (all P > 0.05), except for lower HDL (-0.12 mmol/L; 95% CI: -0.21, 0.04 mmol/L; P = 0.003) and total cholesterol (-0.21 mmol/L; 95% CI: -0.42, 0.00 mmol/L; P = 0.05) in the 20 μg/d than in the 10 μg/d group, which disappeared in the fully adjusted analysis (P = 0.27 and P = 0.30, respectively).

Conclusions

Supplementation with vitamin D3 at 10 and 20 μg/d, which increased serum 25(OH)D concentrations during the winter-time, had no effect on markers of cardiometabolic risk in healthy 14- to 18-y-old adolescents. This trial was registered at clinicaltrials.gov as NCT02150122.

Overfed but undernourished: recognizing nutritional inadequacies/deficiencies in patients with overweight or obesity

Overweight and obesity are highly prevalent throughout the world and can adversely affect the nutritional status of individuals. Studies have shown that many people with obesity have inadequate intake of iron, calcium, magnesium, zinc, copper, folate and vitamins A and B₁₂, likely as a result of poor diet quality. Nutritional inadequacies or deficiencies may also occur due to altered pharmacokinetics in the individual with obesity and due to interactions in those with overweight or obesity with various pharmaceuticals. However, it has been demonstrated that the adult population in the United States as a whole is deficient in certain micronutrients as a result of the availability and overconsumption of high-calorie, low-nutrient processed foods. Poor nutrition may contribute to the development of certain chronic conditions, such as type 2 diabetes, which is already more prevalent in those with obesity. Clinicians need to be aware of these gaps, particularly in those individuals with obesity who are undergoing bariatric surgery or taking pharmaceutical products long term to facilitate weight loss. Patients with overweight or obesity likely struggle to achieve a balanced diet and may benefit from consultation with a dietitian. Along with providing recommendations for healthy eating and exercise, supplementation with specific micronutrients or multivitamins should be considered for individuals at the highest risk for or with established deficiencies. Further research is needed to understand the factors underlying nutritional inadequacies in individuals with overweight or obesity, as well as the outcomes of treatment strategies employed to address them.

Plasma 25-hydroxyvitamin D concentration and risk of type 2 diabetes and pre-diabetes: 12-year cohort study

BACKGROUND

It has been reported that higher plasma 25-hydroxyvitamin D is associated with lower risk of type 2 diabetes. However the results to date have been mixed and no adequate data based on a cohort are available for the high end of the normal range, above approximately 32 ng/ml or 80 nmol/L.

METHODS

We performed a cohort study of 903 adults who were known to be free of diabetes or pre-diabetes during a 1997-1999 visit to a NIH Lipid Research Centers clinic. Plasma 25(OH)D was measured at Visit 8 in 1977-1979. The mean age was 74 years. The visit also included fasting plasma glucose and oral glucose tolerance testing. Follow-up continued through 2009.

RESULTS

There were 47 cases of diabetes and 337 cases of pre-diabetes. Higher 25(OH)D concentrations (> 30 ng/ml) were associated with lower hazard ratios (HR) for diabetes: 30-39 ng/ml or 75-98 nmol/L: HR = 0.31, 95% CI = 0.14-0.70; for 40-49 ng/ml or 100-122 nmol/L: HR = 0.29, CI = 0.12-0.68; for > 50 ng/ml or 125 nmol/L: HR = 0.19, CI = 0.06-0.56. All HRs are compared to < 30 ng/ml or 75 nmol/L. There was an inverse dose-response gradient between 25(OH)D concentration and risk of diabetes with a p for trend of 0.005. Each 10 ng/mL or 25 nmol/L higher 25(OH)D concentration was associated with a HR of 0.64, CI = 0.48-0.86. 25(OH)D concentrations were more weakly inversely associated with pre-diabetes risk, and the trend was not significant.

CONCLUSION

Further research is needed on whether high 25(OH)D might prevent type 2 diabetes or transition of prediabetes to diabetes.

Association between serum 25-hydroxyvitamin D and glycated hemoglobin levels in type 2 diabetes patients with chronic kidney disease

AIMS/INTRODUCTION

Vitamin D is suggested to influence glucose homeostasis. An inverse relationship between serum 25-hydroxyvitamin D (25[OH]D) and glycemic control in non-chronic kidney disease (CKD) patients with type 2 diabetes was reported. We aimed to examine this association among type 2 diabetes patients with CKD.

MATERIALS AND METHODS

A total of 100 type 2 diabetes participants with stage 3-4 CKD were recruited. Blood for glycated hemoglobin (HbA1c ), serum 25(OH)D, renal and lipid profiles were drawn at enrollment. Correlation and regression analyses were carried out to assess the relationship of serum 25(OH)D, HbA1c and other metabolic traits.

RESULTS

A total of 30, 42, and 28% of participants were in CKD stage 3a, 3b and 4, respectively. The proportions of participants based on ethnicity were 51% Malay, 24% Chinese and 25% Indian. The mean (±SD) age and body mass index were 60.5 ± 9.0 years and 28.3 ± 5.9 kg/m2 , whereas mean HbA1c and serum 25(OH)D were 7.9 ± 1.6% and 37.1 ± 22.2 nmol/L. HbA1c was negatively correlated with serum 25(OH)D (rs = -0.314, P = 0.002), but positively correlated with body mass index (rs = 0.272, P = 0.006) and serum low-density lipoprotein cholesterol (P = 0.006). There was a significant negative correlation between serum 25(OH)D and total daily dose of insulin prescribed (rs = -0.257, P = 0.042). Regression analyses showed that every 10-nmol/L decline in serum 25(OH)D was associated with a 0.2% increase in HbA1c .

CONCLUSIONS

Lower serum 25(OH)D was associated with poorer glycemic control and higher insulin use among multi-ethnic Asians with type 2 diabetes and stage 3-4 CKD.

Vitamin D and pancreas: The role of sunshine vitamin in the pathogenesis of diabetes mellitus and pancreatic cancer

Increasing evidence suggests that vitamin D exerts multiple effects beyond bone and calcium metabolism. Vitamin D seems to play a role in pancreatic disease, including type 1 and type 2 diabetes mellitus as well as pancreatic cancer. Vitamin D's immune-modulatory action suggests that it could help prevent type 1 diabetes. In type 2 diabetes, vitamin D may influence β-cell function, insulin sensitivity, and systematic inflammation-all characteristic pathways of that disease. Data from observational studies correlated vitamin D deficiency with risk of type 1 and type 2 diabetes. Prospective and ecological studies of pancreatic cancer incidence generally support a beneficial effect of higher 25-hydroxyvitamin D concentration as well as inverse correlations between UVB dose or exposure and incidence and/or mortality rate of pancreatic cancer. This review discusses the literature regarding vitamin D's role in risk of diabetes and pancreatic cancer. The results to date generally satisfy Hill's criteria for causality regarding vitamin D and incidence of these pancreatic diseases. However, large randomized, blinded, prospective studies are required to more fully evaluate the potential therapeutic role of vitamin D in preventing pancreatic diseases.

Association of Vitamin D Deficiency and Degree of Coronary Artery Disease in Cardiac Patients with Type 2 Diabetes

Several modifiable factors may influence cardiac function in diabetic patients. The aim of the study was to evaluate the influence of vitamin D level on the stage of coronary atherosclerosis in cardiac patients diagnosed with type 2 diabetes. The study was performed in 337 consecutive patients undergoing coronarography. The stage of atherosclerosis was evaluated using Coronary Artery Surgery Study Score. The plasma 25(OH)D concentration was determined by an electrochemiluminescence method. Patients without significant lesions in coronary arteries presented the highest 25(OH)D level, significantly higher than patients with one-, two-, and three-vessel coronary artery disease (CAD) (p < 0.01). Significantly lower level of the 25(OH)D was observed in patients hospitalized due to acute coronary syndrome (ACS) in comparison to patients hospitalized due to stable CAD (p < 0.001). Lower 25(OH)D levels were observed in patients with the history of myocardial infarction (MI) in comparison to patients without previous MI (p < 0.001). In cardiac patients with diabetes, the higher number of stenotic coronary arteries is associated with lower values of the 25(OH)D. A group of male cardiac patients with diabetes with significant stenosis in three coronary arteries, hospitalized due to acute coronary syndrome, with a history of previous MI and hyperlipidemia presented the lowest vitamin D level.

No effect of vitamin D supplementation on cardiovascular risk factors in subjects with metabolic syndrome: a pilot randomised study

Introduction

Patients with metabolic syndrome (MetS) may have lower 25-hydroxyvitamin D (25(OH)VitD) serum levels compared with non-MetS individuals. Vitamin D (VitD) deficiency is associated with various cardiovascular disease (CVD) risk factors. Yet, the effect of VitD supplementation on MetS remains uncertain. Our aim was to examine the effect of VitD supplementation on CVD risk factors in MetS subjects.

Material and methods

This pilot study had a PROBE (prospective, randomised, open-label, blinded end-point) design. Fifty patients with MetS were included and randomised either to dietary instructions (n = 25) (control group) or dietary instructions plus VitD 2000 IU/day (n = 25) (VitD group) for 3 months. This study is registered in ClinicalTrials.gov (NCT01237769).

Results

In both groups a similar small weight reduction was achieved. In the VitD group serum 25(OH)VitD levels significantly increased by 91% (from 16.0 (3.0–35.0) to 30.6 (8.4–67.0) ng/ml, p < 0.001), while in the control group no significant change was observed (from 10.0 (4.0–39.6) to 13.0 (3.5–37.0) ng/ml). In both groups triglycerides, high-density lipoprotein cholesterol, low-density lipoprotein cholesterol, fasting glucose, haemoglobin A_1c, homeostasis model assessment index and diastolic blood pressure did not significantly change. Systolic blood pressure decreased by 3.7% (from 134 ±14 to 129 ±13 mm Hg, p = 0.05) in the VitD group, while it decreased by 1.5% (from 132 ±13 to 130 ±16 mm Hg, p = NS) in the control group (p = NS between groups). In the VitD group serum 25(OH)VitD increase was negatively correlated with SBP decrease (r = –0.398, p = 0.049).

Conclusions

VitD supplementation (2000 IU/day) did not affect various CVD risk factors in patients with MetS.

25-hydroxyvitamin D is associated with adiposity and cardiometabolic risk factors in a predominantly vitamin D-deficient and overweight/obese but otherwise healthy cohort

Vitamin D deficiency has reached epidemic proportions worldwide and has recently been linked to cardiometabolic risk factors including obesity, insulin resistance, hypertension, dyslipidemia, as well as type 2 diabetes and cardiovascular disease. The objective of this study was to examine the associations between circulating 25-hydrovitamin D (25(OH)D) levels and cardiometabolic risk factors using direct measures of adiposity, glucose intolerance, and insulin resistance, as well as lipids, blood pressure, and plasma markers of inflammation. We measured circulating 25(OH)D, physical activity (International Physical Activity Questionnaire- IPAQ), anthropometry (body mass index (BMI), waist-to-hip ratio (WHR), % body fat (dual energy X-ray absorptiometry)), metabolic parameters (fasting and 2-h plasma glucose levels during oral glucose tolerance test; insulin sensitivity (M, hyperinsulinaemic-euglycaemic clamp), and cardiovascular and inflammatory profiles (blood pressure (BP), pulse pressure (PP), mean arterial pressure (MAP), plasma lipid levels, white blood cell count (WBC), and plasma high-sensitivity C-reactive protein levels (hsCRP)) in 111 healthy, non-diabetic adults (66 males/45 females; age 31.1±9.2years; % body fat 36.0±10.2%). Mean 25(OH)D was 39.8±19.8 nmol/L with no difference between genders (p=0.4). On univariate analysis, 25(OH)D was associated with% body fat (r=-0.27; p=0.005), 2-h glucose (r=-0.21; p=0.03), PP (r=0.26; p=0.006), and insulin sensitivity (r=0.20, p=0.04), but not with age, BMI, WHR, fasting glucose, BP, MAP, lipids, or inflammatory markers (all p>0.05). After adjusting for age and sex, 25(OH)D remained associated with% body fat (β=-0.12%; p=0.003), 2-h glucose (β=-0.13mmol/L; p=0.02), PP (β=0.12mmHg; p=0.009), and insulin sensitivity (β=0.22mg/kg/min; p=0.03), and became associated with fasting glucose (β=-0.04mmol/L; p=0.04) and hsCRP (β=-0.51mg/L; p=0.04). After adjusting for age, sex, and % body fat, 25(OH)D was no longer associated with insulin sensitivity, 2-h glucose, or hsCRP, but remained associated with fasting glucose (β=-0.05mmol/L; p=0.03) and PP (β=0.10mmHg; p=0.03). 25(OH)D remained associated with fasting glucose (β=-0.06mmol/L; p=0.02) after hsCRP and physical activity were added to the model with % body fat, age, and sex. ​These cross-sectional data suggest that associations between vitamin D and cardiometabolic risk among healthy, non-diabetic adults are largely mediated by adiposity. Large-scale intervention and mechanistic studies are needed to further investigate whether vitamin D has an independent role in the prevention and/or management of cardiometabolic risk and disease.

The protective effect of 1alpha, 25-dihydroxyvitamin d3 and metformin on liver in type 2 diabetic rats

There is an accumulating evidence suggesting an immunomodulatory role of 1α,25(OH)₂D3. Altered 1α,25(OH)₂D3 level may play a role in the development of T2DM and contribute to the pathogenesis of liver diseases. Our study was designed to study and compare the effect of metformin and 1α,25(OH)₂D3 supplementation on liver injury in type 2 diabetic rat. Sixty male Albino rats were divided into 5 groups; group 1: control rats. the remaining rats were fed high fat diet for 2 weeks and injected with streptozotocin (35mg/kg BW, i.p.) to induce T2DM and were divided into: group 2: untreated diabetic rats, group 3: diabetic rats treated by metformin (100mg/kgBW/d, orally), group 4: diabetic rats supplemented by 1α,25(OH)₂D3 (0.5μg/kg BW, i.p.) 3 times weekly and group 5: supplemented by both 1α,25(OH)₂D3 and metformin. Eight weeks later, serum glucose and insulin levels were measured, HOMA IR was calculated, lipid profile, Ca2+, ALT and AST were estimated. Liver specimens were taken to investigate PPAR-α (regulator of lipid metabolism), NF-κB p65, caspase 3 and PCNA (proliferating cell nuclear antigen) and for histological examination. The liver enzymes were elevated in the diabetic rats and the histological results revealed an injurious effect of diabetes on the liver. 1α,25(OH)₂D3, metformin and both drugs treatment significantly improved liver enzymes as compared to the untreated rats. The improvement was associated with a significant improvement in the glycemic control, lipid profile and serum Ca2+ with a significant reduction in NF-κB p65 and caspase 3 and increased PPAR-α, and PCNA expression as compared to the untreated group. 1α,25(OH)₂D3 induced a slightly better effect as compared to metformin. Both agents together had a synergistic action and almost completely protected the liver. Histological results confirmed the biochemical findings. Our results showed a protective effect of 1α,25(OH)₂D3 and metformin on liver in diabetic rats as indicated by an improvement of the level of the liver enzymes, decreased apoptosis and increased proliferation and this was confirmed histologically, with modulating NFkB and PPAR-α. Both agents together had a synergistic effect.

Does vitamin D play a role in autoimmune endocrine disorders? A proof of concept

In the last few years, more attention has been given to the "non-calcemic" effect of vitamin D. Several observational studies and meta-analyses demonstrated an association between circulating levels of vitamin D and outcome of many common diseases, including endocrine diseases, chronic diseases, cancer progression, and autoimmune diseases. In particular, cells of the immune system (B cells, T cells, and antigen presenting cells), due to the expression of 1α-hydroxylase (CYP27B1), are able to synthesize the active metabolite of vitamin D, which shows immunomodulatory properties. Moreover, the expression of the vitamin D receptor (VDR) in these cells suggests a local action of vitamin D in the immune response. These findings are supported by the correlation between the polymorphisms of the VDR or the CYP27B1 gene and the pathogenesis of several autoimmune diseases. Currently, the optimal plasma 25-hydroxyvitamin D concentration that is necessary to prevent or treat autoimmune diseases is still under debate. However, experimental studies in humans have suggested beneficial effects of vitamin D supplementation in reducing the severity of disease activity. In this review, we summarize the evidence regarding the role of vitamin D in the pathogenesis of autoimmune endocrine diseases, including type 1 diabetes mellitus, Addison's disease, Hashimoto's thyroiditis, Graves' disease and autoimmune polyendocrine syndromes. Furthermore, we discuss the supplementation with vitamin D to prevent or treat autoimmune diseases.

The Effect of Improved Serum 25-Hydroxyvitamin D Status on Glycemic Control in Diabetic Patients: A Meta-Analysis

BACKGROUND

Type 2 diabetes is a global health concern, with an increased prevalence and high cost of treatment.

OBJECTIVE

The aim of this systematic review and meta-analysis was to determine the effect of vitamin D supplementation and improved vitamin D status on glycemia and insulin resistance in type 2 diabetic patients.

DATA SOURCE

We searched PUBMED/Medline, Cumulative Index to Nursing and Allied Health, and Cochrane Library (until January 2017).

STUDY SELECTION

Prospective clinical trials were selected evaluating the impact of vitamin D supplementation on glycosylated hemoglobin (HbA1c), serum fasting plasma glucose (FPG), and homeostatic model assessment of insulin resistance (HOMA-IR) in diabetic patients.

DATA EXTRACTION AND SYNTHESIS

We used a random-effects model to synthesize quantitative data, followed by a leave-one-out method for sensitivity analysis. The systematic review registration was CRD42017059555. From a total of 844 entries identified via literature search, 24 controlled trials (1528 individuals diagnosed with type 2 diabetes) were included. The meta-analysis indicated a significant reduction in HbA1c [mean difference: -0.30%; 95% confidence interval (CI): -0.45 to -0.15, P < 0.001], FPG [mean difference: -4.9 mg/dL (-0.27 mmol/L); 95% CI: -8.1 to -1.6 (-0.45 to -0.09 mmol/L), P = 0.003], and HOMA-IR (mean difference: -0.66; 95% CI: -1.06 to -0.26, P = 0.001) following vitamin D supplementation and significant increase in serum 25-hydroxyvitamin D levels [overall increase of 17 ± 2.4 ng/mL (42 ± 6 nmol/L)].

CONCLUSIONS

Vitamin D supplementation, a minimum dose of 100 µg/d (4000 IU/d), may significantly reduce serum FPG, HbA1c, and HOMA-IR index, and helps to control glycemic response and improve insulin sensitivity in type 2 diabetic patients.

[Vitamin D : More than just a bone hormone]

Vitamin D plays an essential role in the primary therapy and prevention of osteoporosis. Established vitamin D effects are renal and intestinal resorption of calcium and phosphate for optimal bone mineral density; however, the widespread distribution of the vitamin D receptor (VDR), a member of the nuclear steroid hormone receptor family, provides extensive evidence for additional pleiotropic effects of the vitamin D ligand. Vitamin D deficiency and insufficiency are common and were reported as risk factors for a variety of diseases in observational studies. In addition, extensive research from experimental studies also illustrated extraskeletal effects of vitamin D. More randomized controlled trials are ongoing to test the effects of high dose vitamin D supplementation in numerous chronic diseases. This article summarizes the current state of knowledge regarding effects on muscle, on glucose metabolism in type 2 diabetes mellitus and on cardiovascular risk factors and diseases. Furthermore, we discuss the influence of vitamin D on the immune system, whereby vitamin D might provide beneficial effects not only for infectious but also for autoimmune diseases, such as type 1 diabetes mellitus. Current evidence leads to the conclusion that vitamin D deficiency should be avoided in these diseases. Recommendations for optimal dosage are discussed.