No difference in vitamin D levels between children newly diagnosed with type 1 diabetes and their healthy siblings: a 13-year nationwide Danish study

Vitamin D status in longstanding type 1 diabetes and controls. Association with upper extremity impairments

Background

Patients with type 1 diabetes have a high prevalence of upper extremity impairments (UEIs), such as frozen shoulder, carpal tunnel syndrome, and trigger finger. The UEIs are strongly associated with activity limitations and impaired quality of life. The etiology of the UEI is not clear. Vitamin D deficiency has been considered to play a role in the pathogenesis of type 1 diabetes and in the development of macro- and microvascular complications in diabetes.

Aim

To characterize vitamin D status in a large population of patients with type 1 diabetes, if vitamin D deficiency is associated with metabolic factors and possible association with UEI.

Material and methods

Patients who diagnosed before 35 years of age, whose diabetes duration >20 years, and who are not older than 65 years were invited to participate in this cross-sectional case-control, multicenter study. Controls matched for age and sex were obtained from the national population registry. Fasting blood samples were collected and stored at -80°C until analyzed regarding 25-hydroxy-vitamin D (25(OH)D3) by a liquid chromatographic-mass spectrometric method (LC-MS/MS).

Results

Vitamin D levels varied with season as expected in the northern hemisphere. The association between 25(OH)D3 and clinical variables was analyzed in a univariate general linear model, which indicated no difference in 25(OH)D3 in men with and without diabetes but higher values in women with diabetes. About 30% of both patients and controls had vitamin D deficiency (≤50 nmol/L). Analyzed by binary logistic regression UEIs was not associated with 25(OH)D3 levels. In both patients and controls, 25(OH)D3 was correlated to apolipoprotein A1 (r = 0.153; 0.220, P < 0.001).

Conclusion

In patients with type 1 diabetes and a duration of 20 years or more, vitamin D level is not lower than in nondiabetic controls and is not associated with UEIs.

Vitamin D and Vascular Disease

Cardiovascular disease (CVD) is a major cause of morbidity and mortality worldwide. Vitamin D deficiency has been identified as a potential risk factor for a number of diseases unrelated to the classical skeletal pathophysiology, such as cancer and CVD, but the effects of vitamin D supplementation are less clear. Purpose of this narrative review is to discuss the evidence suggesting an association between vitamin D status and CVD as well as the results of supplementation studies. Vitamin D deficiency has been associated with CVD risk factors such as hypertension, dyslipidemia and diabetes mellitus as well as with cardiovascular events such as myocardial infarction, stroke and heart failure. While vitamin D deficiency might contribute to the development of CVD through its association with risk factors, direct effects of vitamin D on the cardiovascular system may also be involved. Vitamin D receptors are expressed in a variety of tissues, including cardiomyocytes, vascular smooth muscle cells and endothelial cells. Moreover, vitamin D has been shown to affect inflammation, cell proliferation and differentiation. While observational studies support an association between low plasma vitamin D levels and increased risk of CVD, Mendelian randomization studies do not support a causal association between the two. At present, high quality randomized trials do not find evidence of significant effects on CVD endpoints and do not support supplementation of vitamin D to decrease CVD events.

Vitamin D levels and risk of type 1 diabetes: A Mendelian randomization study

BACKGROUND

Vitamin D deficiency has been associated with type 1 diabetes in observational studies, but evidence from randomized controlled trials (RCTs) is lacking. The aim of this study was to test whether genetically decreased vitamin D levels are causally associated with type 1 diabetes using Mendelian randomization (MR).

METHODS AND FINDINGS

For our two-sample MR study, we selected as instruments single nucleotide polymorphisms (SNPs) that are strongly associated with 25-hydroxyvitamin D (25OHD) levels in a large vitamin D genome-wide association study (GWAS) on 443,734 Europeans and obtained their corresponding effect estimates on type 1 diabetes risk from a large meta-analysis of 12 type 1 diabetes GWAS studies (Ntot = 24,063, 9,358 cases, and 15,705 controls). In addition to the main analysis using inverse variance weighted MR, we applied 3 additional methods to control for pleiotropy (MR-Egger, weighted median, and mode-based estimate) and compared the respective MR estimates. We also undertook sensitivity analyses excluding SNPs with potential pleiotropic effects. We identified 69 lead independent common SNPs to be genome-wide significant for 25OHD, explaining 3.1% of the variance in 25OHD levels. MR analyses suggested that a 1 standard deviation (SD) decrease in standardized natural log-transformed 25OHD (corresponding to a 29-nmol/l change in 25OHD levels in vitamin D-insufficient individuals) was not associated with an increase in type 1 diabetes risk (inverse-variance weighted (IVW) MR odds ratio (OR) = 1.09, 95% CI: 0.86 to 1.40, p = 0.48). We obtained similar results using the 3 pleiotropy robust MR methods and in sensitivity analyses excluding SNPs associated with serum lipid levels, body composition, blood traits, and type 2 diabetes. Our findings indicate that decreased vitamin D levels did not have a substantial impact on risk of type 1 diabetes in the populations studied. Study limitations include an inability to exclude the existence of smaller associations and a lack of evidence from non-European populations.

CONCLUSIONS

Our findings suggest that 25OHD levels are unlikely to have a large effect on risk of type 1 diabetes, but larger MR studies or RCTs are needed to investigate small effects.

Vitamin D status in Israeli pediatric type 1 diabetes patients: the AWeSoMe Study Group experience and literature review

Background The prevalence of both vitamin D (VitD) deficiency and type 1 diabetes mellitus (T1DM) has increased worldwide over the last few decades. The objectives of this study were: (1) to evaluate the prevalence of VitD deficiency and insufficiency among Israeli youth with T1DM and (2) to assess the association between VitD status, seasonality and T1D glycemic control characteristics. Methods This was a multi-centered, cross-sectional study. VitD levels were routinely tested during the years 2008-2011 in T1DM patients aged up to 21 years. Medical records were reviewed for demographic, clinical and laboratory characteristics. Results The study population consisted of 199 participants (53% males), mean age 12.24±4.11 years, mean T1DM duration 3.77±3.43 years. VitD levels were within the normal range in 19.6%, insufficient (15-29 ng/mL, 37-72 nmol/L) in 62.3% and deficient (<15 ng/mL, <37 nmol/L) in 18.1%. Mean VitD level was higher during the summer than during spring, autumn and winter (28.65 ng/mL, 23.16 ng/mL, 21.65 ng/mL, 17.55 ng/mL, respectively, p<0.001). Mean VitD level was higher among secular patients compared to the religious (whole-year heavily dressed) population (23.57 ng/mL, 15.54 ng/mL, respectively, p<0.001). VitD level was negatively associated with body mass index calculation of standard deviation scores (BMI-SDS), high-density lipoprotein (HDL) and age at diagnosis (r=-0.171, p=0.016; r=-0.149, p=0.043; r=-0.150, p=0.037, respectively). No association was demonstrated with disease duration and glycemic control indices and metabolic parameters. Conclusions VitD insufficiency is largely prevalent among Israeli youth with T1DM, as is in Israeli youth in general. The VitD level is associated with seasonality, clothing habits and BMI.

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.

Vitamin D in pediatric age: consensus of the Italian Pediatric Society and the Italian Society of Preventive and Social Pediatrics, jointly with the Italian Federation of Pediatricians

Vitamin D plays a pivotal role in the regulation of calcium-phosphorus metabolism, particularly during pediatric age when nutritional rickets and impaired bone mass acquisition may occur.Besides its historical skeletal functions, in the last years it has been demonstrated that vitamin D directly or indirectly regulates up to 1250 genes, playing so-called extraskeletal actions. Indeed, recent data suggest a possible role of vitamin D in the pathogenesis of several pathological conditions, including infectious, allergic and autoimmune diseases. Thus, vitamin D deficiency may affect not only musculoskeletal health but also a potentially wide range of acute and chronic conditions. At present, the prevalence of vitamin D deficiency is high in Italian children and adolescents, and national recommendations on vitamin D supplementation during pediatric age are lacking. An expert panel of the Italian Society of Preventive and Social Pediatrics reviewed available literature focusing on randomized controlled trials of vitamin D supplementation to provide a practical approach to vitamin D supplementation for infants, children and adolescents.

'25-Hydroxyvitamin D, Autoantigenic and Total Antibody Concentrations: Results from a Danish Case-control Study of Newly Diagnosed Patients with Childhood Type 1 Diabetes and their Healthy Siblings'

B cells have recently entered the stage as an important accessory player in type 1 diabetes (T1D) etiopathogenesis. Experimental studies suggest regulatory functions of vitamin D on B cells. However, only a few human studies, with considerable methodological limitations, have been conducted within this field. Our objective was to investigate whether higher 25-hydroxyvitamin D (25(OH)D) concentrations were inversely associated with β-cell autoantigens glutamic acid decarboxylase (isoform 65) (GADA) and insulinoma-associated antigen-2A (IA-2A). Further, we also wanted to examine the relationship between 25(OH)D and total antibody concentrations. We randomly selected 500 patients with newly diagnosed T1D and 500 siblings for 25(OH)D, antibody and genetic analysis from the population-based Danish Registry of Childhood and Adolescent Diabetes. The relative change (RC) in the mean concentration of GADA, IA-2A and antibody isotypes by a 10 nmol/l increase in 25(OH)D concentration was modelled by a robust log-normal regression model. We found no association between 25(OH)D and GADA [adjusted RC per 10 nmol/l increase: 1.00; 95% confidence interval (CI): 0.98-1.02] and IA-2A [adjusted RC per 10 nmol/l increase: 0.92; CI: 0.76-1.12]. Further, 25(OH)D was not associated with the total concentration of antibody isotypes [immunoglobulin (Ig)A, IgE, IgG and IgM]. All null findings were unaltered after adjustment for genetic variation in the vitamin D pathway. Physiological concentrations of 25(OH)D are unlikely to have a clinically important effect on antibody concentrations in a paediatric population of newly diagnosed patients with T1D and their healthy siblings.

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.

25-Hydroxyvitamin D and Peripheral Immune Mediators: Results from Two Nationwide Danish Pediatric Cohorts

(1) Background: We aimed to examine if 25-hydroxyvitamin D (25(OH)D) was related to the peripheral immunological and inflammatory signature both at birth, and in newly diagnosed patients with childhood type 1 diabetes (T1D) and their healthy controls; (2) Methods: The birth cohort consisted of 470 patients and 500 healthy controls. Dried blood samples were collected from the neonates in the period 1981–1999. The newly diagnosed cohort consisted of 460 patients and 453 siblings. Serum samples were collected in the period 1997–2005. A variety of peripheral immune mediators were measured and compared to total 25(OH)D levels (25(OH)D₂ + 25(OH)D₃). For each immune mediator, the relative change (RC) in the mean level was modeled by robust log-normal regression and correction for multiple testing was performed; (3) Results: Two associations were identified; there was a negative association between 25(OH)D (10 nmol/L increase) and leptin (RC (95% confidence interval (CI)), 0.98 (0.96; 1.00)), and a positive association between 25(OH)D (10 nmol/L increase) and the chemokine, chemokine (c-x-c motif) ligand (CXCL) 8 (RC (95% CI), 1.07 (1.01; 1.13)); (4) Conclusion: CXCL8 and leptin have significant associations with levels of 25(OH)D in the newly diagnosed cohort. These results do not indicate a strong influence of 25(OH)D on the peripheral immunological or inflammatory signature.

Epidemiology of Skeletal Health in Type 1 Diabetes

The skeleton is adversely affected by type 1 diabetes (T1D). Patients with T1D of both sexes have an increased risk of fracture that begins in childhood and extends across the entire lifespan. T1D is characterized by mild to modest deficits in bone density, structure, and microarchitecture. Current evidence suggests that the observed bone deficits in T1D are the result of impaired bone formation rather than increased bone resorption. There is emerging data that bone quality is impaired in T1D, which may explain the findings that fracture risk is elevated out of proportion to the degree of bone mineral deficit. In this review, we summarize the current knowledge regarding the epidemiology of skeletal health in T1D. Given the high individual and societal burden of osteoporotic fracture, there is an urgent need to better understand the etiology of T1D-related bone disease so that clinical strategies to prevent fracture can be developed.

Vitamin D and extra-skeletal health: causality or consequence

Vitamin D deficiency /insufficiency is widely recognized as a global health problem that is likely to be involved in pathogenesis or progression of many acute and chronic health disorders. Its relation to skeletal health has been clearly demonstrated and thoroughly examined. This review aims to highlight the continuous debate about the relation between vitamin D and extra-skeletal health and whether it is a causality or just an association. Overall, the available evidence does not meet the criteria for establishing cause-and-effect relationships because of the limitations of observational studies to corroborate the causality due to many potential confounders. Moreover, the causal relationship couldn't be established in randomized studies or in many meta-analyses. This may reflect the fact that vitamin D level reduction is just a biomarker of ill health. The inflammatory processes involved in the disease occurrence and the functional limitations of the diseases would have a role in reducing serum 25-hydroxy vitamin D "25 (OH) D" level, which would explain why low vitamin D is reported in a wide range of disorders. This may underscore the possibility of harm instead of benefit of vitamin D supplementation when its exact role is not fully established, thus many guidelines and interest groups are still hesitant toward recommending replacement in extra-skeletal disease. Future directions entails the need for a large well-designed randomized control trials (RCTs) to resolve the active debate on the benefits of vitamin D replacement for extra-skeletal disease, and not only that, future studies should establish specific, clinically relevant effects of vitamin D repletion, provide cut-values for optimal serum levels of 25 (OH) D, and appropriate doses for non-skeletal health benefits.

Seasonality of diagnosis of type 1 diabetes mellitus in the Netherlands (Young Dudes-2)

BACKGROUND

The aim of this study was to investigate seasonality in the initial presentation of type 1 diabetes mellitus (T1DM) among Dutch children.

METHODS

Observational, nationwide study in the Netherlands. Using the national registry for both healthcare reimbursement and pharmaceutical care, data of all Dutch children (aged 0-14 years) with a diagnosis of T1DM in the period 2009-2011 were obtained.

RESULTS

During the study period (2009-2011) an average annual number of 2.909.537 children aged 0-14 lived in the Netherlands and 676 children were diagnosed with T1DM per year, translating into an annual incidence rate (IR) of T1DM of 23.2 per hundred thousand children (ptc). The annual IR differed significantly (p=0.03) between seasons: 6.4 ptc in winter, 4.9 ptc in spring, 5.4 ptc in summer and 6.6 ptc in autumn. This pattern was present within both boys and girls Conclusions: Among Dutch children aged 0-14 years, there is seasonality in the of T1DM with a peak incidence in autumn and winter.

Seasonal variation in month of diagnosis in children with type 1 diabetes registered in 23 European centers during 1989-2008: little short-term influence of sunshine hours or average temperature

BACKGROUND

The month of diagnosis in childhood type 1 diabetes shows seasonal variation.

OBJECTIVE

We describe the pattern and investigate if year-to-year irregularities are associated with meteorological factors using data from 50 000 children diagnosed under the age of 15 yr in 23 population-based European registries during 1989-2008.

METHODS

Tests for seasonal variation in monthly counts aggregated over the 20 yr period were performed. Time series regression was used to investigate if sunshine hour and average temperature data were predictive of the 240 monthly diagnosis counts after taking account of seasonality and long term trends.

RESULTS

Significant sinusoidal pattern was evident in all but two small centers with peaks in November to February and relative amplitudes ranging from ± 11 to ± 38% (median ± 17%). However, most centers showed significant departures from a sinusoidal pattern. Pooling results over centers, there was significant seasonal variation in each age-group at diagnosis, with least seasonal variation in those under 5 yr. Boys showed greater seasonal variation than girls, particularly those aged 10-14 yr. There were no differences in seasonal pattern between four 5-yr sub-periods. Departures from the sinusoidal trend in monthly diagnoses in the period were significantly associated with deviations from the norm in average temperature (0.8% reduction in diagnoses per 1 °C excess) but not with sunshine hours.

CONCLUSIONS

Seasonality was consistently apparent throughout the period in all age-groups and both sexes, but girls and the under 5 s showed less marked variation. Neither sunshine hour nor average temperature data contributed in any substantial way to explaining departures from the sinusoidal pattern.

The role of Toll-like receptors and vitamin D in diabetes mellitus type 1--a review

It is widely accepted that type 1 diabetes mellitus (T1DM) is an autoimmune disease resulting from an interaction between immunologic, genetic and environmental factors. However, the exact mechanism leading to the development of T1DM remains incomplete. There is a large body of evidence pointing towards the important role of toll-like receptor (TLR) activation and vitamin D deficiency in T1DM pathogenesis. In this article, we review the available data on the influence of TLRs' level of activation and vitamin D status on the risk of the development of T1DM in humans and rodent models. We also summarize the current information regarding the interactions between TLRs' level of activation, vitamin D status and various environmental factors, such as enteroviral infections, the gut microbiota and breastfeeding substitution, among others. Our results stipulate that vitamin D seems to protect against T1DM by reducing the TLRs' level of activation.

No association between type 1 diabetes and genetic variation in vitamin D metabolism genes: a Danish study

BACKGROUND

Vitamin D, certain single nucleotide polymorphisms (SNPs) in the vitamin D-receptor (VDR) gene and vitamin D metabolism genes have been associated with type 1 diabetes (T1D).

OBJECTIVE

We wanted to examine if the most widely studied SNPs in genes important for production, transport, and action of vitamin D were associated with T1D or to circulating levels of vitamin D 25-hydroxyvitamin D [25(OH)D] in a juvenile Danish population.

METHODS

We genotyped eight SNPs in five vitamin D metabolism genes in 1467 trios. 25(OH)D status were analyzed in 1803 children (907 patients and 896 siblings).

RESULTS

We did not demonstrate association with T1D for SNPs in the following genes: CYP27B1, VDR, GC, CYP2R1, DHCR7, and CYP24A1. Though, variants in the GC gene were significantly associated with 25(OH)D levels in the joint model.

CONCLUSION

Some of the most examined SNPs in vitamin D metabolism genes were not confirmed to be associated with T1D, though 25(OH) levels were associated with variants in the GC gene.

The role of vitamin D deficiency in cardiovascular disease: where do we stand in 2013?

The high worldwide prevalence of vitamin D deficiency is largely the result of low sunlight exposure with subsequently limited cutaneous vitamin D production. Classic manifestations of vitamin D deficiency are linked to disturbances in bone and mineral metabolism, but the identification of the vitamin D receptor in almost every human cell suggests a broader role of vitamin D for overall and cardiovascular health. The various cardiovascular protective actions of vitamin D such as anti-diabetic and anti-hypertensive effects including renin suppression as well as protection against atherosclerosis and heart diseases are well defined in previous experimental studies. In line with this, large epidemiological studies have highlighted vitamin D deficiency as a marker of cardiovascular risk. However, randomized controlled trials (RCTs) on vitamin D have largely failed to show its beneficial effects on cardiovascular diseases and its conventional risk factors. While most prior vitamin D RCTs were not designed to assess cardiovascular outcomes, some large RCTs have been initiated to evaluate the efficacy of vitamin D supplementation on cardiovascular events in the general population. When considering the history of previous disappointing vitamin RCTs in general populations, more emphasis should be placed on RCTs among severely vitamin D-deficient populations who would most likely benefit from vitamin D treatment. At present, vitamin D deficiency can only be considered a cardiovascular risk marker, as vitamin D supplementation with doses recommended for osteoporosis treatment is neither proven to be beneficial nor harmful in cardiovascular diseases.