Vitamin D and diabetes

Infections and Autoimmunity-The Immune System and Vitamin D: A Systematic Review

Both 25-autoimmunity and(25(OH)D: calcifediol) and its active form, 1,25-dihydroxyvitamin D (1,25(OH)2D: calcitriol), play critical roles in protecting humans from invasive pathogens, reducing risks of autoimmunity, and maintaining health. Conversely, low 25(OH)D status increases susceptibility to infections and developing autoimmunity. This systematic review examines vitamin D's mechanisms and effects on enhancing innate and acquired immunity against microbes and preventing autoimmunity. The study evaluated the quality of evidence regarding biology, physiology, and aspects of human health on vitamin D related to infections and autoimmunity in peer-reviewed journal articles published in English. The search and analyses followed PRISMA guidelines. Data strongly suggested that maintaining serum 25(OH)D concentrations of more than 50 ng/mL is associated with significant risk reduction from viral and bacterial infections, sepsis, and autoimmunity. Most adequately powered, well-designed, randomized controlled trials with sufficient duration supported substantial benefits of vitamin D. Virtually all studies that failed to conclude benefits or were ambiguous had major study design errors. Treatment of vitamin D deficiency costs less than 0.01% of the cost of investigation of worsening comorbidities associated with hypovitaminosis D. Despite cost-benefits, the prevalence of vitamin D deficiency remains high worldwide. This was clear among those who died from COVID-19 in 2020/21-most had severe vitamin D deficiency. Yet, the lack of direction from health agencies and insurance companies on using vitamin D as an adjunct therapy is astonishing. Data confirmed that keeping an individual's serum 25(OH)D concentrations above 50 ng/mL (125 nmol/L) (and above 40 ng/mL in the population) reduces risks from community outbreaks, sepsis, and autoimmune disorders. Maintaining such concentrations in 97.5% of people is achievable through daily safe sun exposure (except in countries far from the equator during winter) or taking between 5000 and 8000 IU vitamin D supplements daily (average dose, for non-obese adults, ~70 to 90 IU/kg body weight). Those with gastrointestinal malabsorption, obesity, or on medications that increase the catabolism of vitamin D and a few other specific disorders require much higher intake. This systematic review evaluates non-classical actions of vitamin D, with particular emphasis on infection and autoimmunity related to the immune system.

Prevalence and Associated Factors of Vitamin D Deficiency in High Altitude Region in Saudi Arabia: Three-Year Retrospective Study

Background

Vitamin D has many functions in the human body, and its deficiency is associated with skeletal and non-skeletal diseases. Vitamin D deficiency (blood level of 25 (OH) vitamin D < 20 ng/mL) has been reported worldwide, including Kingdom of Saudi Arabia (KSA). Its prevalence and associated factors vary according to KSA region. Therefore, this study aimed to explore the prevalence and risk factors of vitamin D deficiency in the Taif region of KSA.

Methods

This retrospective study included patients who attended outpatient clinics at the Alameen General Hospital from 2019 to 2021. Demographic, clinical, and laboratory data were collected using a hospital software system.

Results

The study included 2153 patients and vitamin D deficiency was diagnosed in 900 (41.8%) of whom were diagnosed with vitamin D deficiency. It was more common in males (P=0.021), younger age (<0.001), and in patients without comorbidities. There was a positive correlation between 25 (OH) vitamin D levels and blood cholesterol, high-density lipoprotein, calcium, and vitamin B12 levels. In the binary logistic regression analysis, age was the most significant predictor (P<0.001), followed by the absence of thyroid disease (P=0.012) and asthma (P=0.030).

Conclusion

Vitamin D deficiency is common in the Saudi population despite sunny weather in KSA. It is more prevalent among males, younger individuals, and those without comorbidities such as thyroid diseases and asthma.

Vitamin D insufficiency and its association with adipokines and atherogenic indices in patients with metabolic syndrome: A case-control study

INTRODUCTION

Vitamin D deficiency is one of the most common nutritional disorders in most countries of the world. The present study was designed and implemented with the aim of investigating the relationship between vitamin D deficiency and the level of adipokines, atherogenesis indicators and factors related to metabolic syndrome.

METHODS

This case-control study was done on 195 patients with metabolic syndrome aged 20-50 y who attended the health centers in Zabol County, northeast Iran, between April 2021 and January 2022. Anthropometric and biochemical parameters were measured for all subjects with standard methods. To determine serum 25(OH)D levels, we used enzymatic linked immunosorbent assay (ELISA) kits. Atherogenic index of plasma (AIP) was calculated as log (TG/HDL-c). The visceral adiposity index (VAI) and the lipid accumulation product (LAP) were estimated according to standard formulas.

RESULTS AND DISCUSSION

Participants in the case group had lower serum levels of 25(OH)D compared to controls (19.8 ± 6.2 ng/ml vs. 41.2 ± 9.7ng/ml, P<0.001). We found that the mean serum levels of fasting blood sugar (P=0.023) and TG (P=0.008) as well as HOMA-IR (P=0.023) were significantly higher in the cases compared to controls. Also, patients with MetS and vitamin D insufficiency (cases) had higher AIP (P=0.040) and LAP (P=0.012) than controls. Furthermore, serum 25(OH)D levels showed significant inverse correlations with serum RBP-4 and a positive correlation with serum omentin-1 concentrations. The results of the present study showed that vitamin D deficiency correlated with some of the cardiometabolic risk factors among the patients with MetS.

Long-term cholecalciferol supplementation in hemodialysis patients: Effects on mineral metabolism, inflammation, and cardiac parameters

BACKGROUND

Low levels of 25-hydroxyvitamin D [25(OH)D] are frequent in chronic kidney disease and are associated with adverse outcomes. The aim of this 5-year prospective study was to evaluate the effects of cholecalciferol supplementation on mineral metabolism, inflammation and cardiac parameters in hemodialysis (HD) patients.

METHODS

The study included 97 patients. Cholecalciferol was given after HD according to 25(OH)D baseline levels measured twice (end of winter and of summer). The 25(OH)D levels, circulating bone metabolism, inflammation parameters, brain natriuretic peptide (BNP), pulse pressure (PP), and left ventricular mass index (LVMI) were evaluated before and after supplementation.

RESULTS

There was a significant increase in 25(OH)D levels after supplementation (p < 0.001); however, serum calcium (p = 0.02), phosphorus (p = 0.018), and iPTH (p = 0.03) were decreased. Magnesium levels increased during the study (p = 0.03). A reduction in the number of patients under active vitamin D (p < 0.001) and in the dose and number of patients treated with darbepoetin (p = 0.02) was observed. Serum albumin increased (p < 0.001), and C-reactive protein decreased (p = 0.01). BNP (p < 0.001), PP (p = 0.007), and LVMI (p = 0.02) were significantly reduced after supplementation.

CONCLUSIONS

Long-term cholecalciferol supplementation allowed correction of 25(OH)D deficiency, improved mineral metabolism with less use of active vitamin D, attenuated inflammation, reduced the dose of the erythropoiesis-stimulating agent, and improved cardiac dysfunction.

Environmental Factors and the Risk of Developing Type 1 Diabetes-Old Disease and New Data

Simple Summary

Despite many studies, the risk factors of type 1 diabetes (T1DM) in children and adolescents are still not fully understood and remain a big challenge. Therefore, an extensive online search for scientific research on factors related to diabetes has been performed for the identification of new factors of unexplained etiology. A better understanding of the role of viral, bacterial, and yeast-like fungi infections related to the risk of T1DM in children and adolescents and the identification of new risk factors, especially those spread by the droplet route, is of great importance for people and families with diabetes.

Abstract

The incidence of type 1 diabetes (T1D) is increasing worldwide. The onset of T1D usually occurs in childhood and is caused by the selective destruction of insulin-producing pancreatic islet cells (β-cells) by autoreactive T cells, leading to insulin deficiency. Despite advanced research and enormous progress in medicine, the causes of T1D are still not fully understood. Therefore, an extensive online search for scientific research on environmental factors associated with diabetes and the identification of new factors of unexplained etiology has been carried out using the PubMed, Cochrane, and Embase databases. The search results were limited to the past 11 years of research and discovered 143 manuscripts published between 2011 and 2022. Additionally, 21 manuscripts from between 2000 and 2010 and 3 manuscripts from 1974 to 2000 were referenced for historical reference as the first studies showcasing a certain phenomenon or mechanism. More and more scientists are inclined to believe that environmental factors are responsible for the increased incidence of diabetes. Research results show that higher T1D incidence is associated with vitamin D deficiency, a colder climate, and pollution of the environment, as well as the influence of viral, bacterial, and yeast-like fungi infections. The key viral infections affecting the risk of developing T1DM are rubella virus, mumps virus, Coxsackie virus, cytomegalovirus, and enterovirus. Since 2020, i.e., from the beginning of the COVID-19 pandemic, more and more studies have been looking for a link between Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) and diabetes development. A better understanding of the role of viral, bacterial, and yeast-like fungi infections related to the risk of T1DM in children and adolescents and the identification of new risk factors, especially those spread by the droplet route, is of great importance for people and families with diabetes.

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.

Investigating the Effects of Diet-Induced Pre-Diabetes on the Functioning of Calcium-Regulating Organs in Male Sprague Dawley Rats: Effects on Selected Markers

Derangements to the functioning of calcium-regulating organs have been associated with type 2 diabetes mellitus (T2DM), a condition preceded by pre-diabetes. Type 2 diabetes has shown to promote renal calcium wastage, intestinal calcium malabsorption and increased bone resorption. However, the changes to the functioning of calcium-regulating organs in pre-diabetes are not known. Subsequently, the effects of diet-induced pre-diabetes on the functioning of calcium-regulating organs in a rat model for pre-diabetes was investigated in this study. Male Sprague Dawley rats were separated into two groups (n=6, each group): non-pre-diabetic (NPD) group and a diet-induced pre-diabetic (DIPD) group for 20 weeks. After the experimental period, postprandial glucose and HOMA-IR were analysed in addition to plasma and urinary calcium concentrations. Gene expressions of intestinal vitamin D (VDR), intestinal calbindin-D9k, renal 1-alpha hydroxylase and renal transient receptor potential vanilloid 5 (TRPV5) expressions in addition to plasma osteocalcin and urinary deoxypyridinoline concentrations were analysed at week 20. The results demonstrated significantly increased concentrations of postprandial glucose, HOMA-IR and urinary calcium in addition to unchanged plasma calcium levels in the DIPD group by comparison to NPD. Renal TRPV5, renal 1-alpha hydroxylase, intestinal VDR and intestinal calbindin-D9k expressions were increased in the DIPD group by comparison to NPD. Furthermore, plasma osteocalcin levels were increased and urine deoxypyridinoline levels were decreased in the DIPD group by comparison to NPD. These observations may suggest that calcium-regulating organs compensate for the changes to calcium homeostasis by inducing increased renal calcium reabsorption, increased intestinal calcium absorption and decreased bone resorption followed by increased bone formation.

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.

MicroRNA‑378d inhibits Glut4 by targeting Rsbn1 in vitamin D deficient ovarian granulosa cells

Vitamin D (VD) is not only associated with bone growth and development, but is also closely associated with numerous other pathological conditions. The present study aimed to investigate the effect of microRNA (miRNA/miR)-378d on ovarian granulosa cells by regulating the round spermatid basic protein 1 (Rsbn1) in the absence of VD. The abnormal expression of miRNAs in ovarian tissues of the VD-deficient mouse was analyzed using transcriptome sequencing. miR-378d, glucose transporter 4 (Glut4) and aromatase (Cyp19a) expression levels were examined via reverse transcription-quantitative (RT-q)PCR and western blotting. The expression levels of Rsbn1, Glut4 and Cyp19a were detected in transfected mouse ovarian granulosa cells. The targeting regulation between miR-378d and Rsbn1 was verified using double reporter gene assay and functional rescue experiments. Among the 672 miRNAs that were differentially expressed, cluster analysis revealed that 17 were significantly upregulated and 16 were significantly downregulated. Moreover, miR-378d showed significant upregulation, which was further verified via RT-qPCR. It was identified that the protein expression level of Rsbn1 was significantly downregulated. Furthermore, Glut4 mRNA expression was significantly decreased in the mimic group but markedly increased in the inhibitor group. By contrast, the mRNA expression levels of Rsbn1 and Cyp19a did not demonstrate any significant difference. The western blotting results indicated that the protein expression levels of Rsbn1 and Glut4 were decreased and increased, respectively, while Cyp19a did not show any significant change. In addition, the double reporter gene experiments confirmed that Rsbn1 was the target gene of miR-378d. Collectively, the present results demonstrated that miR-378d was abnormally overexpressed in the ovarian tissues of the VD-deficient mice, and that miR-378d could inhibit Glut4 production by targeting Rsbn1, which may lead to insulin resistance.

Association of Vitamin D Deficiency with Cardiovascular Disease Among Saudi Patients in Saudi Arabia

Background:

Vitamin D deficiency has a far-reaching impact on several metabolic functions including cardiovascular health. This study aimed to test the association of serum 25 [OH]-vitamin D3 levels among cardiovascular disease (i.e., hypertension and ischemic heart disease) patients.

Methods:

A cross-sectional study was conducted among 360 participants from the tertiary care hospital. The simple random technique was used to select the participants. Only Saudi nationals were included in the study. Sociodemographic information, nutritional status, biochemical parameter (lipid profile, blood glucose level), and questions relating to cardiovascular disease were collected from the hospital record through data collection sheet. Serum Vit D level was determined by serum 25 (OH) blood test. Statistical package for social science (SPSS) software version 24 was used for data analysis. Binary logistic regression model was fitted to indentify the associated factors of vitamin D deficiency among cardiovascular disease patients.

Results:

Approximately 40.6% and 27.8% of study participants had vitamin D deficiency and insufficiency, respectively. After adjustment of covariates, among cardiac patients, vitamin D deficiency was associated with ischemic heart disease (OR 2.24, 95% CI 1.11–4.52), and blood triglyceride level (OR 2.27, 95% CI 1.22–4.22).

Conclusions:

Vitamin D deficiency and insufficiency are associated with ischemic heart disease, hyperglycemia, and hypertriglyceridemia. There is a need for the screening of cardiovascular disease patients for vitamin D levels.

Vitamin D Deficiency May Not Be an Independent Risk Factor for Peripheral Arterial Disease in Middle-Aged and Elderly Patients with Type 2 Diabetes in China

Background

Vitamin D deficiency can lead to the increased severity and prevalence of metabolic disorders. However, the relationship between levels of 25-hydroxyvitamin D (25(OH)D) and peripheral arterial disease (PAD) is controversial. Therefore, the purpose of our study was to explore the relationship between 25(OH)D levels and PAD in middle-aged and elderly type 2 diabetes mellitus (T2DM) patients in China.

Methods

In this study, a total of 183 patients with T2DM were enrolled and categorized into groups with or without PAD. Clinical and biochemical parameters were assessed, and a Pearson analysis was used to identify a possible association between levels of 25(OH)D and glycated hemoglobin (HbA1c). Some biochemical parameters were also assessed in the T2DM patients with PAD according to vitamin D status. Interactions were also explored among HbA1c control, 25(OH)D levels, and PAD. The possible risk factors for PAD were measured by multivariable logistic regression analyses.

Results

Firstly, the parameters including age, HbA1c, and disease duration between T2DM and T2DM+PAD groups showed significantly different. In addition, the frequency of smoking in the group of T2DM patients was significantly less than that in the T2DM patients with the PAD group, while the frequency of well-controlled HbA1c in the patients with T2DM was significantly higher. There is a trend that the levels of 25(OH)D and HbA1c are correlated, but no interactions among vitamin D deficiency, HbA1c control, and PAD were found. However, HbA1c significantly differed between groups with vitamin D deficiency and insufficiency in the T2DM patients with PAD. According to the multivariate logistic regression analyses, the PAD risk factors of T2DM patients were family history of diabetes, smoking, age, disease duration, HbA1c, and LDL.

Conclusions

The findings demonstrate that the deficiency of vitamin D level is not related to PAD, but HbA1c may be linked to the presence of PAD in middle-aged and elderly patients with T2DM in China.

Overview of dietary supplements on patients with type 2 diabetes

BACKGROUND AND AIMS

The primary approach for managing type 2 diabetes mellitus (T2DM) involves lifestyle modification and diet therapy along with pharmacologic interventions. Many patients are interested to identify nutritional supplements that may provide benefit in prevention and management of diabetes. However, the efficacy and safety of nutritional supplements such as chromium, n-3 polyunsaturated fatty acids (PUFAs), vitamin D, zinc and magnesium in disease treatment is a worrying and controversial matter. In this narrative review, patients and health care providers are introduced to the effects of mentioned dietary supplements that may help in choosing or not choosing these supplements in treatment of diabetes.

METHODS

This review was carried out using comprehensive and systematic literature reports on the dietary supplements in the management of diabetes. Empirical searches were conducted using Google Scholar, Science Direct and PubMed databases. Searches were also undertaken using keywords, in English, such as "chromium" OR "vitamin D" OR "omega-3 fatty acids" OR "zinc" OR "magnesium" in combination with "type 2 diabetes".

RESULTS

The available evidence is insufficient to create a definite conclusion that nutritional supplements including chromium, n-3 PUFAs, vitamin D, zinc and magnesium might be beneficial for the prevention and treatment of T2DM and therefore, the general recommendation to use these supplements in the management of diabetes cannot be justified. The results of most studies lack uniformity across multiple aspects, including different dose and formation of supplements, duration, and subjects under intervention.

CONCLUSIONS

There is a need for well-designed, high quality, large and long-term studies to strengthen the available evidence and ensure the safety and efficacy of products.

Vitamin D status among adults (18-65 years old) attending primary healthcare centres in Qatar: a cross-sectional analysis of the Electronic Medical Records for the year 2017

OBJECTIVES

To investigate the prevalence of vitamin D deficiency among individuals attending primary healthcare facilities in Qatar and to assess the association between vitamin D deficiency and some medical conditions in persons aged 18-65 years old.

SETTING

The study was undertaken in publicly funded primary healthcare services in the State of Qatar.

PARTICIPANTS

A total of 102 342 participants aged between 18 and 65 years old with a valid serum vitamin D test result during the year 2017.

OUTCOME MEASURES

Serum level <10 ng/mL (<25 nmol/L) was defined as severe vitamin D deficiency, a serum level of <20 ng/mL (<50 nmol/L) was defined as vitamin D deficiency and a serum level <30 ng/mL (<75 nmol/L) defined as vitamin D insufficiency.

RESULTS

The prevalence rate of severe vitamin D deficiency was 14.1% among study participants with no history of vitamin D replacement therapy in the previous months. The prevalence rate of vitamin D deficiency was as high as 71.4% and that of vitamin D insufficiency was up to 92.7%. None of the five chronic conditions explored in the study (diabetes, hypertension, asthma, stroke and cardiovascular disease) had an obvious association with severe vitamin D deficiency status in a bivariate analysis. However, multivariate modelling showed that (adjusting for age, gender, body mass index and nationality and each of the included chronic conditions) hypertension, cardiovascular diseases and stroke placed an individual at a higher risk of having an associated severe vitamin D deficiency status.

CONCLUSION

Although not comprehensive and nationally representative, this study is suggestive of a higher prevalence of vitamin D deficiency among young adults, females, Qatari nationality and those with higher body mass index. Multivariate modelling showed that hypertension, cardiovascular diseases and stroke were associated with a higher risk of severe vitamin D deficiency status.

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.

Changes in Vitamin D Status in Overweight Middle-Aged Adults with or without Impaired Glucose Metabolism in Two Consecutive Nordic Summers

Background

Sun exposure is the main driver of vitamin D synthesis. High latitude, obesity, and type 2 diabetes mellitus (T2DM) are all risk factors for vitamin D deficiency. However, the seasonal variation in vitamin D concentrations (25[OH]D) in such populations before and after sun exposure during the summer is unknown. Therefore, we investigated 25[OH]D status before and after two consecutive summers in high latitude and its associations with body fat, sex, and glucose metabolism.

Methods

158 participants from Sweden (87 women, 71 men; mean age, 60 ± 5 y; body mass index ≥ 25 kg/m²) and 25[OH]D were measured and evaluated in relation to normal or impaired glucose tolerance, body composition, and dietary habits during summer season.

Results

Eighty-four percent of the participants were categorized with low to deficient 25[OH]D values before summer (55.1 ± 21.7 nmol·L⁻¹), with a significant increase after the summer season (66.3 ± 21.0 nmol·L⁻¹; P < 0.001). However, the values remained below the recommended range (76–250 nmol·L⁻¹) in 66% of the participants. These findings were verified in a subgroup of the study population during the subsequent summer. Participants who reported use of vitamin D supplements had higher initial concentrations (64.2 ± 20.1 nmol·L⁻¹) compared to nonusers (53.7 ± 21.7 nmol·L⁻¹; P=0.04). Further, 25[OH]D values correlated negatively with fat mass (kg) prior to summer only in the female population (r=−0.29,  P=0.008).

Conclusions

In the present study, sun exposure had a beneficial but insufficient effect on 25[OH]D levels, and the same levels were documented in two consecutive summer seasons, confirming that vitamin D supplementation in both summer and winter should be considered in this population.

The role of vitamin D in the pathogenesis and treatment of diabetes mellitus: a narrative review

Diabetes mellitus, a metabolic disorder associated with chronic complications, is traditionally classified into two main subtypes. Type 1 diabetes mellitus (T1DM) results from gradual pancreatic islet β cell autoimmune destruction, extending over months or years. Type 2 diabetes mellitus (T2DM) is a heterogeneous disorder, with both insulin resistance and impairment in insulin secretion contributing to its pathogenesis. Vitamin D is a fat-soluble vitamin with an established role in calcium metabolism. Recently, several studies have provided evidence suggesting a role for it in various non-skeletal metabolic conditions, including both types of diabetes mellitus. Preclinical studies of vitamin D action on insulin secretion, insulin action, inflammatory processes, and immune regulation, along with evidence of an increase of hypovitaminosis D worldwide, have prompted several epidemiological, observational, and supplementation clinical studies investigating a potential biological interaction between hypovitaminosis D and diabetes. This narrative review aims to summarize current knowledge on the effect of vitamin D on T1DM and T2DM pathogenesis, prevention, and treatment, as well as on micro- and macrovascular complications of the disease. Furthermore, on the basis of current existing evidence, we aim to highlight areas for potential future research.

1,25-Dihydroxyvitamin D3 enhances glucose-stimulated insulin secretion in mouse and human islets: a role for transcriptional regulation of voltage-gated calcium channels by the vitamin D receptor

AIM

Vitamin D deficiency in rodents negatively affects glucose-stimulated insulin secretion (GSIS) and human epidemiological studies connect poor vitamin D status with type 2 diabetes. Previous studies performed primarily in rat islets have shown that vitamin D can enhance GSIS. However the molecular pathways linking vitamin D and insulin secretion are currently unknown. Therefore, experiments were undertaken to elucidate the transcriptional role(s) of the vitamin D receptor (VDR) in islet function.

METHODS

Human and mouse islets were cultured with vehicle or 1,25-dihydroxyvitamin-D₃ (1,25D₃) and then subjected to GSIS assays. Insulin expression, insulin content, glucose uptake and glucose-stimulated calcium influx were tested. Microarray analysis was performed. In silico analysis was used to identify VDR response elements (VDRE) within target genes and their activity was tested using reporter assays.

RESULTS

Vdr mRNA is abundant in islets and Vdr expression is glucose-responsive. Preincubation of mouse and human islets with 1,25D₃ enhances GSIS and increases glucose-stimulated calcium influx. Microarray analysis identified the R-type voltage-gated calcium channel (VGCC) gene, Cacna1e, which is highly upregulated by 1,25D₃ in human and mouse islets and contains a conserved VDRE in intron 7. Results from GSIS assays suggest that 1,25D₃ might upregulate a variant of R-type VGCC that is resistant to chemical inhibition.

CONCLUSION

These results suggest that the role of 1,25D₃ in regulating calcium influx acts through the R-Type VGCC during GSIS, thereby modulating the capacity of beta cells to secrete insulin.

Vitamin D status of tuberculosis patients with diabetes mellitus in different economic areas and associated factors in China

BACKGROUND

Vitamin D could be a mediator in the association between tuberculosis (TB) and diabetes mellitus (DM). A large scale multi-center study confirmed that TB patients with DM had significantly lower serum vitamin D level compared with those without DM and reported that DM was a strong independent risk factor for vitamin D deficiency.

OBJECTIVES

This study was undertaken to determine amongst patients with both TB and DM living in different economically defined areas in China: i) their baseline characteristics, ii) their vitamin D status and iii) whether certain baseline characteristics were associated with vitamin D deficiency.

METHODS

In DM-TB patients consecutively attending seven clinics or hospitals, we measured 25 hydroxycholecalciferol at the time of registration using electrochemiluminescence in a COBASE 601 Roche analyser by chemiluminescence immunoassay. Data analysis was performed using chi square test and multivariate logistic regression.

RESULTS

There were 178 DM-TB patients that included 50 from economically well-developed areas, 103 from better-off areas and 25 from a poverty area. Median vitamin D levels in well-developed, better-off and poverty areas were 11.5ng/ml, 12.2ng/ml and 11.5ng/ml respectively. Amongst all patients, 149 (84%) had vitamin D deficiency-91 (51%) with vitamin D deficiency (10-19.9 ng/ml) and 58 (33%) with severe deficiency (< 10 ng/ml). There was a significantly higher proportion with vitamin D deficiency in the poverty area. The adjusted odds of vitamin D deficiency (25-(OH)D3 <20 ng/ml) were significantly higher in those with longer history of DM (P = 0.038) and with HbA1c≥10% (P = 0.003).

CONCLUSION

Over 80% of TB patients with DM in China were vitamin D deficient, with risk factors being residence in a poverty area, a long duration of DM and uncontrolled DM. TB programme managers and clinicians need to pay more attention to the vitamin D status of their patients.

Relação entre vitamina D e cálcio no desenvolvimento do Diabetes Mellitus tipo 1 e 2 - Uma revisão de literatura

A prevalência de obesidade, associada a hábitos alimentares inadequados e sedentarismo tem aumentado a ocorrência Diabetes Mellitus, tornando-se um problema de saúde pública. Perspectivas imediatas na mudança do ambiente para reverter o aumento dos níveis de obesidade não são promissores, e existe uma necessidade de considerar outras opções para prevenir o diabetes. Tem sido apontada uma associação inversa entre os baixos níveis da vitamina D e cálcio com a incidencia do Diabetes Mellitus. Desse modo, a vitamina D e o cálcio têm sido propostos como um possível agente terapêutico para a prevenção e tratamento da doença. O objetivo do estudo foi realizar uma revisão de literatura sobre a influência da vitamina D e do cálcio na fisiopatologia do diabetes mellitus, assim como no controle glicêmico.  Estudos têm mostrado que a vitamina D em conjunto com o cálcio são capazes de reduzirem o risco do desenvolvimento do diabetes mellitus tipo 2, enquanto que a insuficiência de vitamina D e de cálcio pode influenciar negativamente a glicemia. Além disso, nível plasmático de 25(OH)D, tem sido correlacionado com o diagnóstico de Diabetes Mellitus tipo 1. Evidências recentes demonstram que a concentração sérica de vitamina D e do cálcio podem estar relacionados ao diabetes. Entretanto, estudos prospectivos e de intervenção em humanos que comprovem a efetividade de ambos, tanto na prevenção como no tratamento dessa doença, ainda são necessários.

Associations of vitamin D with insulin resistance, obesity, type 2 diabetes, and metabolic syndrome

The aim of this study is to determine the relationships of vitamin D with diabetes, insulin resistance obesity, and metabolic syndrome. Intra cellular vitamin D receptors and the 1-α hydroxylase enzyme are distributed ubiquitously in all tissues suggesting a multitude of functions of vitamin D. It plays an indirect but an important role in carbohydrate and lipid metabolism as reflected by its association with type 2 diabetes (T2D), metabolic syndrome, insulin secretion, insulin resistance, polycystic ovarian syndrome, and obesity. Peer-reviewed papers, related to the topic were extracted using key words, from PubMed, Medline, and other research databases. Correlations of vitamin D with diabetes, insulin resistance and metabolic syndrome were examined for this evidence-based review. In addition to the well-studied musculoskeletal effects, vitamin D decreases the insulin resistance, severity of T2D, prediabetes, metabolic syndrome, inflammation, and autoimmunity. Vitamin D exerts autocrine and paracrine effects such as direct intra-cellular effects via its receptors and the local production of 1,25(OH)₂D₃, especially in muscle and pancreatic β-cells. It also regulates calcium homeostasis and calcium flux through cell membranes, and activation of a cascade of key enzymes and cofactors associated with metabolic pathways. Cross-sectional, observational, and ecological studies reported inverse correlations between vitamin D status with hyperglycemia and glycemic control in patients with T2D, decrease the rate of conversion of prediabetes to diabetes, and obesity. However, no firm conclusions can be drawn from current studies, because (A) studies were underpowered; (B) few were designed for glycemic outcomes, (C) the minimum (or median) serum 25(OH) D levels achieved are not measured or reported; (D) most did not report the use of diabetes medications; (E) some trials used too little (F) others used too large, unphysiological and infrequent doses of vitamin D; and (G) relative paucity of rigorous clinical data on the effects of vitamin D sufficiency on non-calcium endpoints. Although a large number of observational studies support improving T2D, insulin resistance, obesity, and metabolic syndrome with vitamin D adequacy, there is a lack of conclusive evidence from randomized control clinical trials that, these disorders are prevented following optimization of serum levels of 25(OH)D. However, none of the currently conducted clinical studies would resolve these issues. Thus, specifically designed, new clinical studies are needed to be conducted in well-defined populations, following normalizing the serum vitamin D levels in vitamin D deficient prediabetes subjects, to test the hypothesis that hypovitaminosis D worsens these disorders and correction would alleviate it.

Non-musculoskeletal benefits of vitamin D

The aim of this study is to determine and critically evaluate the plausible relationships of vitamin D with extra-skeletal tissues in humans. Severe vitamin D deficiency results in rickets in children and osteomalacia in adults; these beneficial effects in the musculoskeletal system and certain physiological functions are well understood. Nevertheless, mounting reports support additional beneficial effects of vitamin D, outside the musculoskeletal system. This review explores the recent advances in knowledge about the non-skeletal effects of vitamin D. Peer-reviewed papers were extracted from research databases using key words, to assess correlations between vitamin D and extra-skeletal diseases and conditions. As per the guidelines of the Preferred Reporting Items for Systematic Reviews (PRISMA); general interpretations of results are included; taking into consideration the broader evidence and implications. This review summarizes current knowledge of the effects of vitamin D status on extra-skeletal tissues with special attention given to relationships between vitamin D status and various diseases commonly affecting adults; the effects of intervention with vitamin D and exposure to sunlight. Evidence suggests that vitamin D facilitates the regulation of blood pressure; and cardiac; endothelial; and smooth muscle cell functions; playing an important role in cardiovascular protection. In addition; 1,25(OH)₂D improves immunity; subdues inflammation; and reduces the incidence and severity of common cancers; autoimmune diseases and infectious diseases. Almost all adequately powered; epidemiological and biological studies that use; adequate doses of vitamin D supplementation in D-deficient populations have reported favorable outcomes. These studies have concluded that optimizing 25(OH)D status improves the functionality of bodily systems; reduces comorbidities; improves the quality of life; and increases survival. Although accumulating evidence supports biological associations of vitamin D sufficiency with improved physical and mental functions; no definitive evidence exists from well-designed; statistically powered; randomized controlled clinical trials. Nevertheless, most studies point to significant protective effects of vitamin D in humans when the minimum 25(OH)D serum level exceeds 30ng/mL and is maintained throughout the year.

Vitamin D supplementation and non-alcoholic fatty liver disease: A critical and systematic review of clinical trials

Previous observational studies have found a relationship between vitamin D deficiency and non-alcoholic fatty liver disease (NAFLD). However, this type of study could not show the causal relationship between these two conditions. Therefore, we systematically and critically reviewed the available clinical trials to elucidate such relationship. We searched databases such as Medline, Scopus and Cochrane to identify the clinical trials that assessed the effects of vitamin D supplementation in adults with NAFLD. The outcome variables of interest were indicators of hepatic steatosis, liver enzymes, insulin resistance, inflammation and oxidative stress. A total of 6 studies were included in the qualitative analysis. Only in two studies the grade of hepatic steatosis decreased significantly after vitamin D supplementation. The changes in insulin resistance parameters were reported significant only in one. Of the 3 included studies that measured biomarkers of inflammation and oxidative stress, one revealed a significant decrease in these biomarkers after vitamin D supplementation. Findings from current review study provided new insight into the factors that could affect the therapeutic role of vitamin D in NAFLD. Factors such as gender differences, baseline serum status of vitamin D, co-supplementation with calcium and gene polymorphism should be considered when designing future clinical trials.

Treating vitamin D deficiency in children with type I diabetes could improve their glycaemic control

Background and aims

The relationship between vitamin D deficiency and type I DM is an ongoing area of interest. The study aims to identify the prevalence of vitamin D deficiency in children and adolescents with T1DM and to assess the impact of treatment of vitamin D deficiency on their glycaemic control.

Methods

Retrospective data was collected from 271 children and adolescents with T1DM. The vitamin D deficient (25(OH)D <30 nmol/L) and insufficient (25(OH)D 30–50 nmol/L) patients were treated with 6000 units of cholecalciferol and 400 units of cholecalciferol, once daily for 3 months respectively. HbA1c and 25(OH)D concentrations were measured before and at the end of the vitamin D treatment.

Results

14.8% from the whole cohort (n = 271) were vitamin D deficient and 31% were insufficient. Among the children included in the final analysis (n = 73), the mean age and plasma 25(OH)D concentration (±SD) were 7.7 years (±4.4) and 32.2 nmol/l (±8.2) respectively. The mean 25(OH)D concentration post-treatment was 65.3 nmol/l (±9.3). The mean HbA1c (±SD) before and after cholecalciferol was 73.5 mmol/mol (±14.9) and 65 mmol/mol (±11.2) respectively (p < 0.001). Children with higher pre-treatment HbA1c had greater reduction in HbA1c (p < 0.001) and those with lower 25(OH)D concentration showed higher reduction in HbA1c (p = 0.004) after treatment.

Conclusions

Low 25(OH)D concentrations are fairly prevalent in children and adolescents with T1DM, treatment of which, can potentially improve the glycaemic control.

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.

Relationship between the Finnish Diabetes Risk Score (FINDRISC), vitamin D levels, and insulin resistance in obese subjects

AIM

To assess the relationship between 25-hydroxyvitamin D [25(OH)D] blood concentrations in subjects with obesity and type 2 diabetes mellitus (T2D) risk according to the Finnish Diabetes Risk Score (FINDRISC) modified for Latin America (LA-FINDRISC).

METHODS

This study was conducted in Ciudad Bolívar, Venezuela. Eighty two women and 20 men (53 obese and 49 nonobese), with an average age of 42.6±12.30 years were enrolled. Weight, height, body mass index (BMI), waist circumference (WC), fasting glucose, basal insulin, plasma lipids, Homeostasis Model Assessment-Insulin Resistance (HOMA-IR), and 25(OH)D levels were measured. FINDRISC with WC cutoff points modified for Latin America was applied.

RESULTS

No difference in 25(OH)D levels between obese and nonobese subjects was found. When anthropometric, clinical, and biochemical variables according to the 25(OH)D status were compared, the only difference detected was higher LA-FINDRISC in the insufficient/low 25(OH)D group compared to normal 25(OH)D levels group (12.75±6.62; vs 10.15±5.21; p=0.031). LA-FINDRISC was negatively correlated with plasma 25(OH)D levels (r=-0.302; p=0.002) and positively correlated with the HOMA-IR index (r=0.637; p=0.0001).

CONCLUSIONS

The LA-FINDRISC significantly correlated with both 25(OH)D levels and insulin resistance markers in this group of patients.

Are low sun exposure and/or vitamin D risk factors for type 1 diabetes?

Ultraviolet radiation and vitamin D, with their known immunosuppressive effects, have the potential to delay or inhibit type 1 diabetes.

High levels of serum vitamin D are associated with a decreased risk of metabolic diseases in both men and women, but an increased risk for coronary artery calcification in Korean men

Background

There are conflicting results for relationships between serum vitamin D levels and metabolic diseases. The aim of this study was to investigate whether serum vitamin D levels were associated with various metabolic diseases including insulin resistance (IR), metabolic syndrome (MS), fatty liver (FL), and coronary artery calcification (CAC), along with assessing gender differences for these relationships in Korean adults.

Methods

A total of 180,918 subjects (98,412 men and 82,506 women) who participated in a comprehensive health examination in the 2012–2013 period at Kangbuk Samsung Hospital, College of Medicine, Sungkyunkwan University were included. Serum vitamin D and metabolic markers were analyzed and CAC was estimated. Subjects were divided according to quartile groups of serum vitamin D. To examine the relationships of serum vitamin D to metabolic diseases and metabolic factors, multivariate logistic analysis was conducted.

Results

High levels of serum vitamin D was associated with lower ORs for MS, IR and FL both in men and women (all p < 0.05). For men, ORs for CAC were significantly higher in third and the highest quartile groups for serum vitamin D in all the analyzed models (all p < 0.05). However, women showed no significant results between serum vitamin D and CAC.

Conclusions

High levels of serum vitamin D were associated with lower risk of MS, IR and FL in both Korean men and women, but were associated with higher risk of CAC only in men, and not in women.

Electronic supplementary material

The online version of this article (doi:10.1186/s12933-016-0432-3) contains supplementary material, which is available to authorized users.

Vitamin D status of psychiatric inpatients at a community teaching hospital in the Midwest

BACKGROUND

Vitamin D deficiency is a re-emerging epidemic in North America. It is increasingly linked to the pathology of cognition and mental illness and is also common in psychiatric patients.

AIMS

This study was designed to determine the prevalence of vitamin D deficiency among psychiatric inpatients in Kansas City, to explore the association between vitamin D status and clinical characteristics, and to identify the association of medical problems related to vitamin D deficiency in mental illness.

METHODS

In this descriptive study we recruited 52 psychiatric inpatients at a community teaching hospital in Kansas City between August and November 2013. A vitamin D-deficient state was defined as serum 25-hydroxyvitamin D (25-(OH) D) level ≤ 20 ng/mL. In addition to descriptive statistics, the Student t-test and Pearson test were used in the study.

RESULTS

A total of 15 patients (28.8%) were classified as deficient, 20 patients (38.5%) had an insufficiency, 17 patients (32.7%) were categorized as sufficient. Interestingly, there was a statistically significant difference in 25-(OH) D levels between African Americans and Caucasians (t = -2.216, p = 0.03) but no significant relationship between 25-(OH) D level and gender, major psychiatric diagnoses, type 2 diabetes mellitus or obesity. There was also no correlation between 25-(OH) D level and age, body mass index or haemoglobin A1C.

CONCLUSIONS

Low 25-(OH) D level was found in a high percentage of psychiatric inpatients in Kansas City. Screening for vitamin D deficiency could be a routine work-up for psychiatric inpatients. Vitamin D supplement for African American inpatients with low vitamin D levels could be considered.

Deficiencies Under Plenty of Sun: Vitamin D Status among Adults in the Kingdom of Saudi Arabia, 2013

BACKGROUND

Vitamin D deficiency has been correlated with several diseases and injuries including diabetes, osteoporosis, fractures, and falls. In the Kingdom of Saudi Arabia (KSA), current data on vitamin D status are lacking.

AIMS

To inform Saudi public health authorities on the current status of blood levels vitamin D deficiency, we analyzed data from the Saudi Health Interview Survey.

MATERIALS AND METHODS

The Saudi Health Interview Survey (SHIS) is a cross-sectional national multistage survey of individuals aged 15 years and above on sociodemographic characteristics, tobacco consumption, diet, physical activity, health care utilization, different health-related behaviors, and self-reported chronic conditions. A total of 10,735 participants completed a health questionnaire and were invited to the local health clinics for biomedical exams.

RESULTS

62.65% of female Saudis and 40.6% of male Saudis aged 15 years and above are deficient in vitamin D. Out of them, less than 1% males and less than 2% females consume vitamin D supplements. Women who have never married and obese individuals are more likely to be deficient in vitamin D, compared to men who were currently married and nonobese individuals. Those consuming vitamin D supplements are less likely to be deficient in vitamin D.

CONCLUSIONS

Our study showed a high prevalence of vitamin D deficiency among Saudi men and women, and the results call for an increased awareness to ensure adequate levels of vitamin D for better health in Saudi Arabia. Moreover, our findings are certainly relevant for other countries in the Gulf region or countries with similar cultures, clothing, and religions.

Clinical implications of vitamin D deficiency

Vitamin D deficiency is a common medical problem worldwide and its prevalence rises along with latitude, obesity, sedentary lifestyle, limited sunlight exposure and aging. A great body of evidence has shown that patients with vitamin D deficiency have increased cardiovascular risks and total mortality. Conversely, the presence of comorbidities progressive with age such as abdominal obesity, insulin resistance, type 2 diabetes and hypertension places the patients at an increased risk of vitamin D deficiency. The multidirectional effect of vitamin D deficiency is present in different phases of the aging process. Based on the literature review, the risk factors for vitamin D insufficiency most often found in post-menopausal women include limited sun exposure and time spent outdoors, inadequate dietary vitamin D intake, winter season and increased age. Vitamin D supplementation in this group might offer prevention of falls and fractures and may be beneficial for cardiovascular health, what may be especially important in osteoporotic and elderly populations. Prevention and treatment processes involve education regarding sunlight exposure and pharmacological cholecalciferol supplementation according to the recommendations for Central Europe. This manuscript reviews the role of vitamin D and its deficiency and considers their clinical implications, with particular regard to peri- and postmenopausal women.

Vitamin D and diabetes: Where do we stand?

The potential beneficial effects of supplementing vitamin D or treatment with pharmacological doses of vitamin D in the prevention or cure of diseases like type 1 (T1D) or type 2 diabetes (T2D) remains the subject of debate. Data from epidemiological and association studies clearly indicate a correlation between vitamin D deficiency and a higher prevalence of both forms of diabetes. In animal models, vitamin D deficiency predisposes to type 1 and type 2 diabetes, whereas high doses of vitamin D or its active hormonal form, 1,25-dihydroxyvitamin D, prevent disease. Large scale, randomized, blinded prospective studies however, remain lacking. Here we discuss the current literature on a role for vitamin D in diabetes. We propose, in particular, to avoid vitamin D deficiency in individuals at risk of developing T1D or T2D. Applying international guidelines on supplementation of vitamin D using small daily doses of vitamin D (500-1000IU) may contribute to reduce the burden of diabetes by preventing vitamin D deficiency. Any other recommendations are at present not supported by data.

Vitamin D and diabetes

There has been increasing evidence that vitamin D may have a role in modifying risk of diabetes. Vitamin D has both direct and indirect effects on various mechanisms related to the pathophysiology of type 2 diabetes, including pancreatic beta cell dysfunction, impaired insulin action and systemic inflammation. This article describes the biologic plausibility behind the potential association between vitamin D and type 2 diabetes and summarizes the current evidence from human studies that suggests but does not prove a relation between vitamin D and type 2 diabetes, and briefly reports on the potential association between vitamin D and type 1 diabetes.

The effect of acute administration of vitamin D on micro vascular endothelial function in Caucasians and South Asian Indians

BACKGROUND

Vitamin D is a modulator of the immune system. There is some limited evidence that it also increases local blood flow in response to stress.

MATERIAL AND METHODS

In the present study, we examined 20 age matched subjects; 10 whom were from India and 10 Caucasians from the United States. Subjects were administered 4000 IU of Vitamin D3 for 3 weeks at breakfast. The function of the endothelial cells was evaluated in 2 ways; first, the response to 4 minutes of vascular occlusion was measured with a laser Doppler flow meter and second, the blood flow response to local heat at 42°C for 6 minutes.

RESULTS

The results of the experiments showed that, as reported previously, the endothelial function in people from India was less than their Caucasian counterparts. The blood flow response to heat was reduced after 3 weeks administration of vitamin D in both groups and the response to vascular occlusion in the Caucasian group. But there was only a 20% reduction in the blood flow response to heat in the Caucasian group and a 50% reduction in the group from India.

CONCLUSIONS

Thus acute doses of vitamin D may increase vascular tone and reduce blood flow to tissue during stressors. Dosages administered for a longer duration may have beneficial effects on endothelial function but this was not examined here.

Variation in ultraviolet radiation and diabetes: evidence of an epigenetic effect that modulates diabetics' lifespan

Background

Published research has shown that month-of-birth variations modulate the incidence of adult human diseases. This article explores diabetes type 2 as one of those diseases. This study uses the death records of approximately 829,000 diabetics (approximately 90% were type-2) born before the year 1945 (and dying between 1979 and 2005) to show that variations in adult lifespan vary with ultraviolet radiation (UVR) at solar cycle peaks (MAX, approximately a three-year period) with less at non-peaks (MIN, approximately an eight-year period). The MAX minus MIN (in years) was our measure of sensitivity (for example, responsiveness) to long-term variations in UVR.

Results

Diabetics were less sensitive than non-diabetics, and ethnic minorities were more sensitive than whites. Diabetic males gained 6.1 years, and females 2.3 years over non-diabetics, with diabetic males gaining an average of 3.8 years over diabetic females. Most variation in lifespan occurred in those conceived around the seasonal equinoxes, suggesting that the human epigenome at conception is especially influenced by rapid variation in UVR. With rapidly decreasing UVR at conception, lifespan decreased in the better-nourished, white, female diabetic population.

Conclusions

Rapidly changing UVR at the equinoxes modulates the expression of an epigenome involving the conservation of energy, a mechanism especially canalized in women. Decreasing UVR at conception and early gestation stimulates energy conservation in persons we consider ‘diabetic’ in today’s environment of caloric surfeit. In the late 19th and early 20th centuries ethnic minorities had poorer nutrition, laborious work, and leaner bodies, and in that environment a calorie-conserving epigenome was a survival advantage. Ethnic minorities with a similar epigenome lived long enough to express diabetes as we define it today and exceeded the lifespan of their non-diabetic contemporaries, while that epigenome in diabetics in the nutritional environment of today is detrimental to lifespan.

Relationship between vitamin D and nonalcoholic fatty liver disease

Vitamin D is an important secosteroid hormone with pleiotropic effects, including regulation of cell proliferation, differentiation, apoptosis, and immunomodulation. Recently certain evidence has indicated that insufficiency of vitamin D or vitamin D deficiency is related to nonalcoholic fatty liver disease (NAFLD). Subjects with NAFLD have lower serum vitamin D levels than controls, and low vitamin D levels are closely associated with histologic severity of steatosis, necrosis, inflammation and fibrosis in NAFLD. Vitamin D-deficient diet aggravated high fat diet-induced hepatic inflammation in NAFLD models, while vitamin D supplementation improved hepatic histopathology. Vitamin D may act as a regulator in NAFLD through activating VDR and controlling various genes. Modulating hepatic stellate cells is an important mechanism underlying the antifibrotic effect of vitamin D in NAFLD. Vitamin D is a potential drug for treatment for NAFLD, and further prospective RCT studies are required to acquire sufficient evidence.

Role of vitamin d in cardiometabolic diseases

Vitamin D deficiency is a highly prevalent condition. Low vitamin D levels have long been associated with bone diseases, such as rickets in children and osteomalacia and osteoporosis in adults. However, it has become apparent in recent years that adequate vitamin D levels are also important for optimal functioning of many organs and tissues throughout the body, including the cardiovascular system. Evolving data indicate that vitamin D deficiency is associated with an increased risk of cardiovascular disease (CVD). Studies have shown that low vitamin D levels are associated with hypertension, diabetes, metabolic syndrome, left ventricular hypertrophy, and chronic vascular inflammation, all of which are risk factors for CVD. This paper reviews the definition and pathophysiology of vitamin D deficiency, clinical evidence linking vitamin D and CVD risk, diabetes and its complications, and metabolic syndrome.

Type 1 diabetes therapy beyond T cell targeting: monocytes, B cells, and innate lymphocytes

Recent clinical trials, investigating type 1 diabetes (T1D), have focused mainly on newly diagnosed individuals who have developed diabetes. We need to continue our efforts to understand disease processes and to rationally design interventions that will be safe and specific for disease, but at the same time not induce undesirable immunosuppression. T cells are clearly involved in the pathogenesis of T1D, and have been a major focus for both antigen-specific and non-antigen-specific therapy, but thus far no single strategy has emerged as superior. As T1D is a multifactorial disease, in which multiple cell types are involved, some of these pathogenic and regulatory cell pathways may be important to consider. In this review, we examine evidence for whether monocytes, B cells, and innate lymphocytes, including natural killer cells, may be suitable targets for intervention.

Vitamin d deficiency and insulin resistance in normal and type 2 diabetes subjects

Vitamin D is recognized to serve a wide range of biological functions. The presence of vitamin D receptors on different tissues explains it's diversity of actions. Reduced levels of vitamin D is associated with insulin resistance and increased diabetes risk. The study included 50 normal healthy individuals and 49 type 2 diabetes subjects. Fasting blood glucose, total cholesterol, triglycerides, HDLc, fasting insulin, parathyroid hormone, calcium, albumin and Homeostasis model for assessment of insulin resistance (HOMAIR) were measured in all the study participants. Type 2 diabetes subjects were divided into group 1 with 25 hydroxy vitamin D (25(OH)D) ≤20 ng/ml and group 2 with 25(OH)D >20 ng/ml. By the results of this study, the mean 25(OH)D level was low (20.09 ng/ml) in type 2 diabetes compared to controls (23.89 ng/ml) and the p value was 0.02. The estimated insulin resistance by HOMAIR was more in group 1 than in group 2 of diabetes with p value of 0.037. The Pearson's correlation-coefficient was negative for 25(OH)D and insulin in type 2 diabetes (r = -0.294), 25(OH)D was negatively correlated with HOMAIR in total subjects. Type 2 diabetes subjects had reduced levels of vitamin D than normal individuals. The insulin resistance was more in vitamin D deficiency state. Hence vitamin D has a role in glucose metabolism, deficiency can result in insulin resistance and diabetes.