Vitamin D levels and mortality in type 2 diabetes

Sodium-glucose cotransporter 2 inhibitors and renin-angiotensin-aldosterone system, possible cellular interactions and benefits

Sodium glucose cotransporter 2 inhibitors (SGLT2is) are a newly developed class of anti-diabetics which exert potent hypoglycemic effects in the diabetic milieu. However, the evidence suggests that they also have extra-glycemic effects. The renin-angiotensin-aldosterone system (RAAS) is a hormonal system widely distributed in the body that is important for water and electrolyte homeostasis as well as renal and cardiovascular function. Therefore, modulating RAAS activity is a main goal in patients, notably diabetic patients, which are at higher risk of complications involving these organ systems. Some studies have suggested that SGLT2is have modulatory effects on RAAS activity in addition to their hypoglycemic effects and, thus, these drugs can be considered as promising therapeutic agents for renal and cardiovascular disorders. However, the exact molecular interactions between SGLT2 inhibition and RAAS activity are not clearly understood. Therefore, in the current study we surveyed the literature for possible molecular mechanisms by which SGLT2is modulate RAAS activity.

Relationship between bone turnover markers and renal disease in elderly patients with type 2 diabetes: a cross-sectional study

OBJECTIVE

The prevalence of type 2 diabetes mellitus (T2DM) and bone metabolism disorders increase with age. Diabetic kidney disease (DKD) is one of the most serious microvascular complications of T2DM, and bone metabolism disorders are closely linked to the occurrence of DKD. The relationship between bone turnover markers(BTMs) and the kidney disease in elderly patients with T2DM remains unclear. Therefore, this study aims to investigate the association between common BTMs and DKD in a large sample of elderly patients. The goal is to provide a basis for early identification of high-risk individuals for DKD among elderly T2DM patients from a bone metabolism perspective.

METHODS

In this cross-sectional study, BTMs were collected from a cohort of 2,051 hospitalized Chinese patients. The relationships between 25-hydroxyvitamin D (25-OH-D), β-CrossLaps (β-CTX), osteocalcin (OSTEOC), intact parathyroid hormone (iPTH), and total type I collagen N-terminal propeptide (TP1NP), and DKD, as well as urinary albumin-to-creatinine ratio (UACR) and estimated glomerular filtration rate (eGFR) were analyzed using regression analysis and restrictive cubic spline (RCS) curves.

RESULTS

Higher 25-OH-D levels were independently linked to a lower incidence of DKD and decreased UACR. The RCS curves showed a linear association of 25-OH-D and DKD, approaching the L-shape. β-CTX was independently and positively correlated with UACR. There is an independent positive correlation between OSTEOC and UACR and a negative correlation with eGFR. iPTH is independently and positively correlated with DKD incidence and UACR, and negatively correlated with eGFR. Additionally, the RCS curves showed a non-linear association of OSTEOC and iPTH and DKD, approaching the J-shape, and the point of inflection is 10.875 ng/L and 34.15 pg/mL respectively. There is an independent positive correlation between TP1NP and UACR incidence, and a negative correlation with eGFR. Risk estimates significantly increase with higher TP1NP levels in the RCS model.

CONCLUSION

BTMs are closely associated with kidney disease in elderly patients with T2DM. These discoveries potentially assist clinicians in establishing more preventive measures and targeted treatment strategies for elderly patients with T2DM.

Genetic Variants in Vitamin-D Metabolism Genes (rs1155563, rs12785878 and rs10500804) among Females with Type-2 Diabetes Mellitus in Saudi Arabia

Background & Objective

Hypovitaminosis D has shown to be linked with T2DM development and control in numerous studies. The association of SNPs in genes related to VitD metabolism with T2DM has not been sufficiently studied. Consequently, our aim in the present study was to explore the association between genetic variants in genes connected with VitD, mainly a SNP in GC (rs1155563), a SNP in DHCR7 (rs12785878) and a SNP in CYP2R1 (rs10500804) with glycaemic parameters in females with T2DM in Saudi Arabia.

Methods

The cross-sectional study included 149 females (age 38-52 years) with T2DM from Jeddah, Saudi Arabia (September 2022-March 2023). Blood was extracted from the participants for biochemical tests including measuring VitD [25(OH)D] concentration, parameters of glycaemia (HbA1c, insulin, fasting glucose and insulin sensitivity indices including HOMA2-IR and HOMA2-%β), and for genomic DNA isolation. Sanger DNA sequencing was used to screen for VitD genetic polymorphisms (rs1155563, rs12785878 and rs10500804).

Results

Minor allele frequency for rs1155563C, rs12785878T and rs10500804G was 0.21, 0.23 and 0.37, respectively. Levels of 25(OH)D and glycaemic parameters as well did not show any significant difference between the genotypes of each SNP.

Conclusion

This study showed lack of association of rs1155563 in GC, rs12785878 in DHCR7 and rs10500804 in CYP2R1 with VitD level primarily and with glycaemic parameters secondarily. Additional research is required to explore further other VitD genetic polymorphisms influencing T2DM which might lead consequently to genetically-based personalized management for T2DM.

Serum 25-Hydroxyvitamin D Level Is Positively Associated with Vascular Reactivity Index in Patients with Type 2 Diabetes Mellitus

Circulating 25-hydroxyvitamin D (25(OH)D) significantly influences endothelial function. This study assessed the correlation between serum 25(OH)D and endothelial function using the vascular reactivity index (VRI) in patients with type 2 diabetes mellitus (T2DM). Fasting blood samples from 102 T2DM participants and VRI were assessed. Patients were divided into three categories based on VRI: low (VRI < 1.0), intermediate (1.0 ≤ VRI < 2.0), and good (VRI ≥ 2.0). Among these patients, 30 (29.4%) had poor, 39 (38.2%) had intermediate, and 33 (32.4%) exhibited good vascular reactivity. Higher serum fasting glucose (p = 0.019), glycated hemoglobin (p = 0.009), and urinary albumin-to-creatinine ratio (p = 0.006) were associated, while lower prevalence of hypertension (p = 0.029), lower systolic blood pressure (p = 0.027), lower diastolic blood pressure (p < 0.001), and lower circulation 25(OH)D levels (p < 0.001) were associated with poor vascular reactivity. Significant independent associations between diastolic blood pressure (p = 0.002) and serum 25(OH)D level (p < 0.001) and VRI were seen in T2DM patients according to multivariable forward stepwise linear regression analysis. Serum 25(OH)D positively correlated with VRI values, and lower levels of serum 25(OH)D were linked to endothelial dysfunction in T2DM patients.

Major impact of vitamin D3 deficiency and supplementation on left ventricular torsional mechanics during dobutamine stress in uncomplicated type 2 diabetes

BACKGROUND AND AIMS

Hypovitaminosis D is associated with the risk of diabetic complications. Its role in diabetic-related cardiac abnormalities remain poorly understood. We aimed therefore to evaluate the effect of vitamin D deficiency and supplementation on early left ventricular (LV) dysfunction in vitamin D deficient patients with uncomplicated T2D.

METHODS AND RESULTS

Sixty-three consecutive T2D patients who had a diagnosis of vitamin D3 were prospectively recruited and allocated into 2 groups (25(OH)D < 20 ng/mL: VDD, >20 ng/mL VDND). Twenty-eight of them with 25(OH)D < 20 ng/mL benefited from a 3-month supplementation. At baseline and follow-up, after conventional echocardiography including evaluation of epicardial adipose tissue (EAT), both LV longitudinal (LS) and circumferential (CS) strains and rotation/twist mechanics were evaluated at rest and during dobutamine (DOB) stress. After treatment, T2D patients successfully normalized their 25(OH)D levels. The strongest associations between vitamin D deficiency and supplementation with LV myocardial function were noticed for torsional mechanics indexes under DOB. EAT correlated significantly (p < 0.01) with baseline 25(OH)D and was reduced after supplementation. Significant correlations were obtained between these 2 parameters with twist or apical rotation at baseline (p < 0.01) and between their delta changes at follow-up (p < 0.01) under DOB. Significant improvements in LS and CS (p < 0.05) under DOB were also underlined at follow-up, with major enhancements noticed in the apical region (p < 0.01) of the LV.

CONCLUSIONS

This study provides the first evidences of the potential of vitamin D supplementation as an efficient prophylactic strategy to alleviate the progression of myocardial dysfunction in asymptomatic patients with uncomplicated T2D.

CLINICALTRIALS

NCT03437421.

Vitamin D deficiency and development of complications in individuals with type 1 and type 2 diabetes: A cohort study

AIMS

To investigate vitamin D deficiency as a risk marker for complications in individuals with type 1 and type 2 diabetes.

METHODS

A cohort study including 1448 adults with type 1 and 770 with type 2 diabetes. Individuals in the decile with lowest vitamin D level were classified as vitamin D deficient. Outcomes based on medical records and registers included mortality, major adverse cardiovascular event (MACE), heart failure, a composite kidney endpoint, albuminuria progression and sight-threatening eye disease. Risk in individuals with vitamin D deficiency was compared to the remaining using adjusted Cox proportional hazards models.

RESULTS

Vitamin D deficiency was associated with higher risk of MACE (adjusted hazard ratio (HR): 2.6; 95 % confidence interval (CI): 1.3-5.2) in type 1, but not in type 2 diabetes. Risk of heart failure was higher in individuals with vitamin D deficiency in both cohorts (HR (95%CI): 16 (4.8-50) in type 1 and 2.4 (1.1-5.5) in type 2 diabetes). Vitamin D deficiency was not associated with development of microvascular complications or mortality.

CONCLUSIONS

Vitamin D deficiency was a risk marker for MACE and heart failure in type 1 and for heart failure in type 2 diabetes, but not for microvascular complications or all-cause mortality.

Serum 25(OH)D Concentration, Vitamin D Supplementation, and Risk of Cardiovascular Disease and Mortality in Patients with Type 2 Diabetes or Prediabetes: a Systematic Review and Dose-Response Meta-Analysis

BACKGROUND

Evidence is uncertain about the association between serum 25-hydroxyvitamin D (25(OH)D) concentration and health outcomes in people with type 2 diabetes.

OBJECTIVES

We aimed to assess the association between vitamin D status and all-cause mortality and cardiovascular disease in people with type 2 diabetes.

METHODS

We did a systematic search in PubMed, Scopus, CENTRAL, and Web of Science until May 2022. We selected 1) cohort studies investigating the association between serum 25(OH)D concentration and mortality or cardiovascular disease in people with type 2 diabetes or prediabetes and 2) randomized trials of vitamin D supplementation in these patients. We used random-effects pairwise meta-analyses to calculate summary relative risks (RRs) and 95% confidence intervals (CI).

RESULTS

21 cohort studies and 6 randomized trials were included. Compared with sufficient vitamin D status (≥50 nmol/L), the RR of all-cause mortality was 1.36 (95% CI: 1.23, 1.49; n = 11 studies, GRADE = moderate) for vitamin D insufficiency (25 to <50 nmol/L), and 1.58 (1.33, 1.83; n = 16, GRADE = moderate) for deficiency (<25 nmol/L). Similar findings were observed for cardiovascular mortality and morbidity but not for cancer mortality. The certainty of evidence ranged from very low to moderate. Dose-response meta-analyses indicated nonlinear associations, with the lowest risk at 25(OH)D ∼60 nmol/L for all-cause and cardiovascular mortality. Supplementation with vitamin D did not reduce the risk of all-cause mortality (RR: 0.96, 95% CI: 0.79, 1.16; risk difference per 1000 patients: 3 fewer, 95% CI: 16 fewer, 12 more; n = 6 trials with 7316 participants; GRADE = low) or the risk of cardiovascular mortality and morbidity (very low- to low-certainty evidence).

CONCLUSIONS

Vitamin D deficiency and insufficiency are associated with a higher risk of all-cause and cardiovascular mortality in patients with type 2 diabetes or prediabetes. Vitamin D deficiency should be corrected in patients with type 2 diabetes to reach normal serum 25(OH)D concentrations, preferably 60 nmol/L.

SYSTEMATIC REVIEW REGISTRATION

This systemic review was registered at PROSPERO as CRD42022326429 (=https://www.crd.york.ac.uk/prospero/display_record.php?RecordID=326429).

Circulating Vitamin D Level and Risk of Sudden Cardiac Death and Cardiovascular Mortality: A Dose-Response Meta-Analysis of Prospective Studies

BACKGROUND

We conducted a comprehensive meta-analysis of prospective cohort studies to analyze the effect of circulating vitamin D level on the risk of sudden cardiac death (SCD) and cardiovascular disease (CVD) mortality.

METHODS

Prospective cohort studies evaluating the association between circulating vitamin D and risk of SCD and CVD mortality were systematically searched in the PubMed and Embase. Extracted data were analyzed using a random effects model and results were expressed in terms of hazard ratio (HR) and 95% confidence interval (CI). Restricted cubic spline analysis was used to estimate the dose-response relationships.

RESULTS

Of the 1,321 records identified using the search strategy, a total of 19 cohort studies were included in the final meta-analysis. The pooled estimate of HR (95% CI) for low vs. high circulating vitamin D level was 1.75 (1.49-2.06) with I² value of 30.4%. In subgroup analysis, strong effects of circulating vitamin D were observed in healthy general population (pooled HR, 1.84; 95% CI, 1.43-2.38) and the clinical endpoint of SCD (pooled HRs, 2.68; 95% CI, 1.48-4.83). The dose-response analysis at the reference level of < 50 nmol/L showed a significant negative association between circulating vitamin D and risk of SCD and CVD mortality.

CONCLUSION

Our meta-analysis of prospective cohort studies showed that lower circulating vitamin D level significantly increased the risk of SCD and CVD mortality.

Effect of vitamin D supplementation on type 2 diabetes biomarkers: an umbrella of interventional meta-analyses

BACKGROUND

Vitamin D supplementation exerts several supporting effects on improving glycemic status, however, results are inconclusive. Thus, in the present study, we aimed to conduct an umbrella of meta-analysis regarding the impact of vitamin D on type 2 diabetes (T2DM) biomarkers.

METHODS

The Scopus, PubMed, Web of Science, Embase, and Google Scholar online databases were searched up to March 2022. All meta-analyses evaluating the impact of vitamin D supplementation on T2DM biomarkers were considered eligible. Overall, 37 meta-analyses were included in this umbrella meta-analysis.

RESULTS

Our findings indicated that vitamin D supplementation significantly decreased fasting blood sugar (FBS) (WMD =  - 3.08; 95% CI: - 3.97, - 2.19, p < 0.001, and SMD =  - 0.26; 95% CI: - 0.38, - 0.14, p < 0.001), hemoglobin A1c (HbA1c) (WMD =  - 0.05; 95% CI: - 0.10, - 0.01, p = 0.016, and SMD =  - 0.16; 95% CI: - 0.27, - 0.05, p = 0.004), insulin concentrations (WMD =  - 2.62; 95% CI: - 4.11, - 1.13; p < 0.001, and SMD =  - 0.33; 95% CI: - 0.56, - 0.11, p = 0.004), and homeostatic model assessment for insulin resistance (HOMA-IR) (WMD =  - 0.67; 95% CI: - 1.01, - 0.32, p < 0.001, and SMD =  - 0.31; 95% CI: - 0.46, - 0.16, p < 0.001).

CONCLUSION

This umbrella meta-analysis proposed that vitamin D supplementation may improve T2DM biomarkers.

Association of vitamin D status with all-cause mortality and outcomes among Chinese individuals with diabetic foot ulcers

AIMS/INTRODUCTION

The aim of this study was to examine the correlation between serum vitamin D concentrations and prognosis among Chinese individuals with diabetic foot ulcers (DFUs).

MATERIALS AND METHODS

We retrospectively recruited 488 adults with DFUs in West China Hospital from 1 January 2012 to 31 December 2019. After telephone follow up, 275 patients were finally included. We compared serum vitamin D concentrations among DFUs patients with different prognostic status, and examined the association of vitamin D status with prognostic variables by Kaplan-Meier analysis. Cox proportional hazards models were used to estimate hazard ratios and 95% confidence intervals for all-cause mortality.

RESULTS

The median concentration of serum vitamin D of patients with DFUs was 37.78 nmol/L (interquartile range 27.91-50.66 nmol/L), with 31.6% having vitamin D deficiency (<30 nmol/L) and 42.2% having insufficient vitamin D (<50 nmol/L). During a median follow-up period of 52 months, 65 patients died, with an all-cause mortality of 23.64%. Vitamin D deficiency was independently linked to increased all-cause mortality after multivariable adjustments (hazard ratio 0.565, 95% confidence interval 0.338-0.946, P = 0.030). There were no significant differences between vitamin D concentrations and other outcomes of DFUs. Patients who suffered amputations had a tendency of lower vitamin D concentrations (34.00 [interquartile range 26.90-41.81] vs 40.21 [interquartile range 29.60-53.96] nmol/L, P = 0.053).

CONCLUSIONS

Vitamin D deficiency was significantly associated with increased all-cause mortality in Chinese individuals with DFUs. Vitamin D supplementation might be a potential therapy for DFUs to prevent premature death and improve outcomes.

Vitamin D status, genetic factors, and risk of cardiovascular disease among individuals with type 2 diabetes: a prospective study

BACKGROUND

The presence of a threshold effect has been proposed, suggesting that beneficial effects from vitamin D supplementation may only be present when vitamin D concentration was below a particular threshold.

OBJECTIVES

To investigate the associations of serum 25-hydroxyvitamin D [25(OH)D] concentrations and genetic factors with risks of total and subtypes of CVD in individuals with type 2 diabetes (T2D), among whom vitamin D deficiency or insufficiency is particularly common.

METHODS

This prospective study included 15,103 individuals with T2D, initially free of CVD and with serum 25(OH)D measurements in UK Biobank. Incidence of total and subtypes of CVD, including ischemic heart disease (IHD) and stroke, were ascertained via electronic health records. Weighted genetic risk scores (GRSs) were constructed for IHD and stroke, respectively.

RESULTS

The mean (standard deviation) of serum 25(OH)D concentration was 43.4 (20.4) nmol/L, and 65.7% participants had vitamin D below 50 nmol/L. During a median of 11.2 years of follow-up, 3,534 incident CVD events were documented. Compared with individuals with 25(OH)D <25 nmol/L, participants with 25(OH)D ≥75 nmol/L had an HR of 0.75 (0.64, 0.88) for CVD, 0.69 (0.56, 0.84) for IHD, and 0.74 (0.52, 1.06) for stroke. Participants with 25(OH)D ≥50 nmol/L and low GRS, as compared with individuals with 25(OH)D <25 nmol/L and high GRS, had a 50% (39%, 65%) lower risk of IHD. No significant interactions between serum 25(OH)D and the GRSs and genetic variants in vitamin D receptor (VDR) were demonstrated.

CONCLUSIONS

Higher serum 25(OH)D concentrations were significantly associated with lower risks of total CVD and IHD among patients with T2D, regardless of genetic susceptibility and genetic variants in VDR. Risk reductions tended to plateau at serum 25(OH)D levels around 50 nmol/L. These findings suggest that maintaining adequate vitamin D status and avoiding deficiency may help to prevent CVD complications among patients with T2D.

Hypovitaminosis D and cardiovascular outcomes: A systematic review and meta-analysis

Background

The relation between blood vitamin D levels and the risk of cardiovascular outcomes is debatable. To our knowledge this is the first comparative meta-analysis of more than 100,000 patients' data with the aim to inspect the relevance of low vitamin D levels with adverse cardiovascular events.

Methods

Online databases including PubMed, Embase and Cochrane Central were queried to compare the cardiovascular outcomes among hypovitaminosis D (HVD) and control group. The outcomes assessed included differences in major adverse cardiovascular events (MACE), mortality, myocardial infarction, and heart failure. Unadjusted odds ratios (OR) were calculated using a random-effect model with a 95% confidence interval (CI) and P less than 0.05 as a statistical significance.

Results

A total of 8 studies including 426,039 patients were included in this analysis. HVD group was associated with a higher incidence of MACE (OR 1.92, 95% CI 1.24 to 2.98, p = 0.003), while there was no significant association of HVD and all-cause mortality (OR 1.77, 95% CI 0.75 to 4.17, p = 0.19), risk of myocardial infarction (OR 0.69, 95% CI 0.39 to 1.24, p = 0.22), and heart failure (OR 1.20, 95% CI 0.34 to 4.25, p = 0.78).

Conclusions

This meta-analysis suggested that low blood levels of vitamin D are associated with MACE, but no such difference in all-cause mortality, myocardial infarction or heart failure was observed. Appropriate supplementation of vitamin D in selected populations might be cardioprotective in nature and warrants extensive trials.

Association of Serum 25(OH)D, Cadmium, CRP With All-Cause, Cause-Specific Mortality: A Prospective Cohort Study

Introduction

To explore the relationship between serum 25(OH)D, cadmium, and CRP with all-cause mortality among people in diabetic and non-diabetic.

Methods

This study used data from the NHANES (2001–2010). Cox regression was used to analyze the relationship between Serum 25(OH)D, cadmium, CRP, and all-cause, cause-specific mortality. We used restricted cubic splines to explore the dose-response relationship between serum 25(OH)D, cadmium, CRP, and all-cause mortality.

Results

During a mean follow-up of 9.1 years, the study included 20,221 participants, 2,945 people with diabetes, and 17,276 people without diabetes. Compared with serum 25(OH)D deficiency group in diabetic patients, the sufficient serum 25(OH)D group was associated with lower all-cause mortality (HR = 0.41, 95%CI 0.28-0.60, P < 0.001) and cardiovascular mortality (HR = 0.46, 95%CI 0.22–0.95, P = 0.04). Compared with the low cadmium group, the high cadmium group was associated with higher all-cause mortality (HR = 1.49, 95%CI 1.06–2.09, P = 0.02). Compared with the low CRP group, the high CRP group was associated with higher all-cause mortality (HR = 1.65, 95%CI 1.24–2.19, P = 0.001) and cancer mortality (HR = 3.25, 95%CI 1.82–5.80, P < 0.001). Restricted cubic splines analysis showed a significant nonlinear association between serum 25(OH)D (P-nonlinearity P < 0.001), cadmium (P-nonlinearity = 0.002), CRP (P-nonlinearity = 0.003), and HR for all-cause mortality risk in diabetic patients. The results were similar among non-diabetic patients, but with different levels of risk. Sensitivity analysis and subgroup analysis presented the results of population studies with different follow-up times, different genders and ages.

Conclusions

In diabetic patients, serum 25(OH)D, cadmium, and CRP were related to all-cause mortality; serum 25(OH)D was related to cardiovascular mortality; CRP was related to cancer mortality. The results were similar among non-diabetic patients, but with different levels of risk.

Vitamin D, Oxidative Stress and Glycaemic Control in Subjects with Type 2 Diabetes Mellitus: Systematic Review

Background:

Diabetes mellitus (DM) is a metabolic and chronic disorder which causes high blood glucose concentrations and dysfunctional pancreatic beta-cells characterized by decreased insulin secretion and signalling. Scientific evidence suggests that vitamin D supplementation may help patients with type 2 diabetes mellitus (T2DM) improve glycaemic control, increasing insulin secretion and decreasing HbA1c concentrations. Additionally, this supplementation improves antioxidant enzyme concentrations, such as superoxide dismutase (SOD), glutathione peroxidase (GPX), catalase (CAT) and total antioxidant capacity (TAC). Finally, some studies have reported that supplementation decreases oxidative markers such as malondialdehyde (MDA).

Materials and methods:

This systematic review was conducted following Reporting Items for Systematic Reviews and Meta-Analyses framework (PRISMA) in terms of study selection, data collection, data analysis, and result reporting. Several databases were reviewed from 2013 to 2020: Google Scholar, REDALYC, Scielo, Scopus and PubMed, among others; word combinations and MeSH keywords were used to find scientific evidence on vitamin D supplementation in patients with T2DM and their relationship with oxidative stress.

Objective:

To review the effect of vitamin D supplementation on glycaemic control and oxidative stress markers in patients with T2DM. Inclusion criteria involved adult patients with T2DM, oral vitamin D supplementation with different dosages and undefined time. Studies in children or animals and with other pathology, were excluded.

Results:

After making a detailed selection of the studies according to its title and abstract, 120 articles were selected for reading the full text. Consequently, 21 studies and 1 report were included in this review including systematic review and meta-analysis.

Conclusion:

Supplementation with vitamin D may help decrease glucose, glycosylated haemoglobin and improve insulin secretion. Subjects with T2DM have higher oxidative stress concentrations and lower antioxidants than healthy subjects; vitamin D supplementation may help improve oxidative and antioxidant markers.

Association of vitamin D receptor gene polymorphism with the occurrence of low bone density, osteopenia, and osteoporosis in patients with type 2 diabetes

Purpose

This study aims to analyze the association between VDR gene polymorphism and the occurrence of "low bone density (LBD)/osteopenia/osteoporosis" or LBDOO in type 2 diabetes (T2D) patients among a clustered population in northwest of Iran. The studied VDR gene polymorphism included ApaI (rs7975232), BsmI (rs1544410), FokI (rs2228570), EcoRV (rs4516035) and, TaqI (rs731236).

Methods

In this population-based cross-sectional study, patients with T2D were identified within a group of 1266 participants based on self-report of diabetes, history of diabetes medication, and recorded laboratory data. Separately for each polymorphism and gender, crude and adjusted (age, BMI) odds ratios (ORs) were calculated for participants with T2D through logistic regression analysis.

Results

The prevalence of T2D was 16.41% in people residing in the city of Sanandaj in 2011. Of the participants with T2D, 13.92% and 81.29% had osteoporosis and vitamin D deficiency, respectively. In women, the tt genotype of the TaqI gene significantly decreased the risk of LBDOO versus the Tt genotype, after adjusting for BMI and age (adjusted OR:0.18, CI_95%: 0.03-0.97). Conversely, the EE genotype of the EcoRV gene enhanced the risk of LBDOO versus the Ee genotype (adjusted OR:7.64, CI_95%: 2.03-28.72).

Conclusion

The polymorphism of both TaqI and EcoRV genes was associated with the risk of LBDOO in women with T2D. This is the first time a study has highlighted this effect for the polymorphism of the EcoRV gene; we believe that this study would serve as a basis for future studies.

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.

Association of Serum 25-Hydroxyvitamin D Concentrations With All-Cause and Cause-Specific Mortality Among Individuals With Diabetes

OBJECTIVE

The evidence regarding vitamin D status and mortality among people with diabetes is scarce. This study aimed to examine the association of serum 25-hydroxyvitamin D [25(OH)D] concentrations with all-cause and cause-specific mortality among adults with diabetes.

RESEARCH DESIGN AND METHODS

This study included 6,329 adults with diabetes from the Third National Health and Nutrition Examination Survey (NHANES III) and NHANES 2001-2014. Death outcomes were ascertained by linkage to National Death Index records through 31 December 2015. Cox proportional hazards models were used to estimate hazard ratios (HR) and 95% CIs for mortality from all causes, cardiovascular disease (CVD), and cancer.

RESULTS

The weighted mean (95% CI) level of serum 25(OH)D was 57.7 (56.6, 58.8) nmol/L, and 46.6% had deficient vitamin D (<50 nmol/L [20 ng/mL]). Higher serum 25(OH)D levels were significantly associated with lower levels of glucose, insulin, HOMA of insulin resistance, HbA_1c, blood lipids, and C-reactive protein at baseline (all P _trend < 0.05). During 55,126 person-years of follow-up, 2,056 deaths were documented, including 605 CVD deaths and 309 cancer deaths. After multivariate adjustment, higher serum 25(OH)D levels were significantly and linearly associated with lower all-cause and CVD mortality: there was a 31% reduced risk of all-cause mortality and a 38% reduced risk of CVD mortality per one-unit increment in natural log-transformed 25(OH)D (both P < 0.001). Compared with participants with 25(OH)D <25 nmol/L, the multivariate-adjusted HRs and 95% CI for participants with 25(OH)D >75 nmol/L were 0.59 (0.43, 0.83) for all-cause mortality (P _trend = 0.003), 0.50 (0.29, 0.86) for CVD mortality (P _trend = 0.02), and 0.49 (0.23, 1.04) for cancer mortality (P _trend = 0.12).

CONCLUSIONS

Higher serum 25(OH)D levels were significantly associated with lower all-cause and CVD mortality. These findings suggest that maintaining adequate vitamin D status may lower mortality risk in individuals with diabetes.

Low Vitamin D Levels are Associated with Vascular Endothelial Dysfunction in Patients with Poorly Controlled Type 2 Diabetes: A Retrospective Study

AIM

This study aimed to determine the association between serum 25-hydroxyvitamin D (25(OH)D) levels and vascular endothelial function in patients with type 2 diabetes (T2D).

METHODS

This retrospective study included 113 patients with poorly controlled T2D who were admitted for in-hospital diabetes educational program and underwent measurements of serum 25(OH)D levels and reactive hyperemia index (RHI).

RESULTS

Serum 25(OH)D levels significantly correlated with RHI in T2D patients. Receiver operating characteristic (ROC) curve analysis showed that serum 25(OH)D level of 16.5 ng/mL is the optimal cutoff level for predicting vascular endothelial dysfunction (RHI＜1.67), with a sensitivity of 68.5%, specificity of 67.9%, and area under the ROC curve of 0.668 (95% confidence interval [CI]: 0.566-0.770, p=0.002). The mean RHI was significantly lower (1.70±0.54) in patients with low 25(OH)D levels (n=56, 25(OH)D levels ＜16.5 ng/mL) than that (1.99±0.58; p＜0.001) in patients with high 25(OH)D levels (n=57, 25(OH)D level ≥ 16.5 ng/mL). The proportion of patients with RHI＜1.67 was higher in the low 25(OH)D group than in the high 25(OH)D group (38% vs. 18%; p＜0.001). Multivariate logistic regression analysis identified that serum 25(OH)D level ＜16.5 ng/mL was associated with increased odds of RHI ＜1.67 (odds ratio 4.598, 95% CI 1.961-10.783, p＜0.001).

CONCLUSION

The results demonstrated the association of serum 25(OH)D levels with endothelial function in poorly controlled T2D patients and identified serum 25(OH)D level of ＜16.5 ng/mL as a predictor of RHI ＜1.67. Serum 25(OH)D level is a potentially useful marker of vascular endothelial dysfunction in poorly controlled T2D patients.

A Nonlinear Relationship Between Serum 25-Hydroxyvitamin D and Urine Albumin to Creatinine Ratio in Type 2 Diabetes: A Cross-Sectional Study in China

BACKGROUND

Diabetic kidney disease often presents as increased urine albumin to creatinine ratio (UACR). 25-hydroxyvitamin D (25(OH)D) is considered as the best indicator of vitamin D status. Previous studies have shown that 25(OH)D is related to the UACR. However, evidence concerning the connection between 25(OH)D and UACR is still limited in the Chinese population.

MATERIALS AND METHODS

A total of 549 participants with type 2 diabetes were enrolled in the study from Shenzhen People's Hospital, China. The participants were grouped by the tertiles of 25(OH)D level. The association between 25(OH)D and UACR was examined by multiple linear regression. A generalized additive model (GAM) was used to verify a non-linear relationship. We conducted a subgroup analysis to evaluate the robustness of the results.

RESULTS

After adjusting for relevant variables, 25(OH)D was negatively correlated with UACR (β = -8.7, 95% CI (-12.0, -5.4)). A non-linear relationship was discovered between 25(OH)D and UACR, and the 25(OH)D threshold was 67. The effect sizes and confidence intervals on the left and right sides of the inflection point were -13.9 (-18.2, -9.6) and 8.9 (-1.1, 18.9), respectively. Subgroup analysis showed a stronger correlation could be detected in males. The same trend also could be found in patients older than 70 years old, those with using ACEI/ARB, with history of hypertension, with SBP ≥140 mmHg and eGFR <60 mL/min/1.73m².

CONCLUSION

The relationship between 25(OH)D and UACR is non-linear. 25(OH)D was negatively related to UACR when 25(OH)D is less than 67 nmol/L.

Plasma 25-Hydroxyvitamin D3 Concentrations and Risk of New-Onset Proteinuria in Patients With Hypertension

OBJECTIVE

We aimed to evaluate the relationship of plasma 25-hydroxyvitamin D3 (25[OH]D3) with the risk of new-onset proteinuria and examine the possible effect modifiers in patients with hypertension and without chronic kidney disease at baseline.

METHODS

This is a post hoc analysis of the renal substudy of the China Stroke Primary Prevention Trial. A total of 1655 patients with hypertension, who had plasma 25(OH)D3 measurements, as well as without proteinuria and with an estimated glomerular filtration rate of ≥60 mL/min/1.73 m² at baseline, were included in the present study. The main outcome was new-onset proteinuria, defined as a urine dipstick reading of ≥1+ at the exit visit.

RESULTS

The mean (standard deviation) 25(OH)D3 level at baseline was 18.6 (7.5) ng/mL. The median follow-up duration was 4.4 years. Overall, there was a significant inverse association between plasma 25(OH)D3 and the risk of new-onset proteinuria (per standard deviation increment; [odds ratio] OR: 0.70; 95% confidence interval [CI]: 0.50, 0.97). Accordingly, when 25(OH)D3 was assessed as quartiles, a significantly lower risk of new-onset proteinuria was found in participants in quartiles 3-4 (≥17.8 ng/mL; OR: 0.45; 95% CI: 0.23, 0.87), compared with those in quartile 1 (<13.1 ng/mL). Furthermore, a stronger inverse relationship of plasma 25(OH)D3 and new-onset proteinuria was observed in nondiabetic participants (per standard deviation increment; OR: 0.57; 95% CI: 0.39, 0.83; vs. diabetics: OR: 1.48; 95% CI: 0.67, 3.28; P for interaction = 0.028).

CONCLUSION

There was a significant inverse association between plasma 25(OH)D3 and the risk of proteinuria in patients with hypertension, especially in those without diabetes.

The correlation between proinsulin, true insulin, proinsulin: True insulin ratio, 25(OH) D3, waist circumference and risk of prediabetes in Hainan Han adults

Purpose

Diabetes mellitus is a kind of highly prevalent chronic disease in the world. The intervention measures on the risk factors of prediabetes contribute to control and reduce the occurrence of diabetes. This study aimed to investigate the correlation between proinsulin (PI), true insulin (TI), PI/TI, 25(OH) D3, waist circumference (WC), and risk of prediabetes.

Methods

In this cross-sectional study, 1662 subjects including 615 prediabetes and 1047 non-prediabetes were recruited. Spearman’s correlation analysis was used to explore the association of PI, TI, PI/TI, 25(OH) D3, and waist circumference with prediabetes. Odds ratios (OR) and 95% confidence intervals (CI) were calculated by logistic regression. Receiver-Operator Characteristic (ROC) curve was used to evaluate the risk of prediabetes.

Results

Our study showed that FPI, 2hPI, FTI, 2hTI, FPI/FTI, and WC could enhance the risk of prediabetes (OR 1.034; OR 1.007; OR 1.005; OR 1.002; OR 3.577, OR 1.053, respectively; all p< 0.001). Stratified analyses indicated that FPI/FTI associated with an increased risk of prediabetes in men (OR 2.080, p = 0.042). FTI have a weak association with prediabetes risk in men and women (OR 0.987, p = 0.001; OR 0.994, p = 0.004, respectively). 2hPI could decrease prediabetes in women (OR 0.995, p = 0.037). Interesting, the sensitivity (86.0%) and AUC (0.942, p< 0.001) of combination (FPI+FTI+2hPI+2hTI+25(OH) D3+WC) were higher than the diagnostic value of these alone diagnoses. The optimal cutoff point of FPI, FTI, 2hPI, 2hTI, 25(OH) D3, and WC for indicating prediabetes were 15.5 mU/l, 66.5 mU/l, 71.5 mU/l, 460.5 mU/l, 35.5 ng/ml, and 80.5 cm, respectively. What’s more, the combination (FPI+FTI+2hPI+2hTI+25(OH) D3+WC) significantly improved the diagnostic value beyond the alone diagnoses of prediabetes in men and women (AUC 0.771; AUC 0.760, respectively).

Conclusion

The FPI, 2hPI, FTI, 2hTI, FPI/FTI, and WC significantly associated with an increased risk of prediabetes. The combination of FPI, FTI, 2hPI, 2hTI, 25(OH) D3, and WC might be used as diagnostic indicators for prediabetes.

The relationship between serum 25-hydroxy vitamin D and blood pressure and quality of life in overweight and obese patients with type 2 diabetes mellitus compared with healthy subjects

Background:

Vitamin D is one of the known lipoprotein hormones with metabolic properties. We aimed to determine the serum 25-hydroxy vitamin D concentration in overweight/obese subjects with diabetes mellitus type Ⅱ (DM Ⅱ) in association with systolic and diastolic blood pressure and quality of life compared with healthy participants.

Methods:

The current case-control study was carried out among 80 overweight/obese subjects with DM Ⅱ, and 77 healthy subjects matched by sex, age and body mass index (BMI). Serum 25-hydroxyvitamin D concentration was measured by ELISA method. In order to examine the quality of life, the Persian version of SF36 questionnaire was used.

Results:

There was significant difference between diabetic and healthy subjects considering serum 25-hydroxyvitamin D concentration (p=0.012). Serum 25-hydroxyvitamin D concentration was inversely correlated with diastolic blood pressure (p=0.02) and positively associated with physical function (p<0.001), social function (p<0.001) and general health (p<0.001) components of quality of life in diabetic subjects and physical health sub-scale (p=0.004) in all participants.

Conclusion:

Serum 25-hydroxyvitamin D concentration was significantly lower in diabetic subjects in comparison with healthy controls. There was a significant reverse relationship between serum concentrations of 25-hydroxyvitamin D with diastolic blood pressure and on the other hand, a significant positive relationship with physical function, social function and general health components and physical health subscale of quality of life in participants with DM Ⅱ.

Assessment of the Role of Serum 25-Hydroxy Vitamin D Level on Coronary Heart Disease Risk With Stratification Among Patients With Type 2 Diabetes Mellitus

We investigated the role of vitamin D on glycemic regulation and cardiac complications in patients with type 2 diabetes mellitus (T2DM). A total of 1139 patients (49.3% males vs 50.7% females) were included. Information on sociodemographic lifestyle, family history, blood pressure (BP), and coronary heart disease (CHD) complications was collected. Significant differences were found between males and females regarding age-groups (P = .002), body mass index (BMI; P = .008), physical activity (P = .010), sheesha smoking (P = .016), cigarette smoking (P = .002), hypertension (P = .050), metabolic syndrome (P = .026), and CHD (P = .020). There were significant differences between vitamin D deficiency, insufficiency, and sufficiency in relation to age-group (P = .002), income (P = .002), waist circumference (P = .002), hip circumference (P = .028), waist-hip ratio (P = .002), and BMI (P = .002). Further, mean values of hemoglobin, magnesium, creatinine, hemoglobin A_1c (HbA_1c), total cholesterol, uric acid, and diastolic BP were significantly higher among patients with vitamin D deficiency compared with those with insufficiency and sufficiency. Multiple logistic regression analysis revealed that 25-hydroxy vitamin D, 25(OH)D, HbA_1c, waist circumference, uric acid, duration of T2DM, total cholesterol, systolic and diastolic BP, and BMI were strong predictor risk factors for CHD among patients with T2DM. The present study supports that 25(OH)D may have a direct effect on CHD and on its risk factors.

Risk Factors of Hypovitaminosis D in HIV-Infected Patients on Suppressive Antiretroviral Therapy

Low serum vitamin D levels are very common in human immunodeficiency virus (HIV)-infected patients. In our cross-sectional study, we investigated the association between 25-hydroxyvitamin D (25(OH)D) levels and serum inflammation markers [C-reactive protein (CRP), white blood cells (WBC), D-dimers, platelet count (PLT)] in 148 HIV-infected patients on combined antiretroviral therapy [28 on tenofovir alafenamide (TAF)] and 40 healthy controls. The controls were significantly older (56.6 ± 19.1 years for HIV(-) vs. 45.1 ± 11.8 years for HIV(+); p = .001) and more females were observed in this group (65% for HIV(-) vs. 16.7% for HIV(+); p = .001). The vitamin D serum level was comparable in the two studied groups (74.2 ± 35.9 nmol/L for HIV(+) vs. 78.0 ± 27.6 nnmol/L for HIV(-), p = .545). In HIV-infected group, a significant positive correlation between CD4+ cell percentage and vitamin D level was observed (r = 0.17; p = .036). Furthermore, the significant negative correlation between vitamin D level and CD8+ cell percentage, PLT, CRP, and D-dimers was seen. In univariate analysis, only TAF use and AIDS status was associated with vitamin D level deficiency. No other antiretroviral (ARV) drug nor gender or smoking had influence on vitamin D serum level. In multivariate analysis, only AIDS status and CRP level were correlated with vitamin D level (slope estimate = 11.6 and p = .032 and slope estimate = -0.83 and p = .002; respectively). In summary, we report that low vitamin D level may be associated with high CRP level in HIV-infected patients on suppressive antiretroviral therapy, especially in AIDS phase. More larger studies are required to assess our observation concerning TAF use and vitamin D level in HIV-positive patients.

Diabetes Mellitus and Vitamin D Deficiency:Comparable Effect on Survival and a DeadlyAssociation after a Myocardial Infarction

Survivors after a myocardial infarction (MI), especially those with diabetes mellitus (DM),remain at high risk of further events. Identifying and treating factors that may influence survivalmay open new therapeutic strategies. We assessed the impact on prognosis of DM andhypovitaminosis D (hypovitD), alone or combined. In this prospective, observational study, 1081patients were enrolled surviving an MI and divided into four groups according to their diabetic andVitD status. The primary end-point was composite of all-cause mortality, angina/MI and heartfailure (HF). Secondary outcomes were mortality, HF and angina/MI. During a follow-up of 26.1months (IQR 6.6-64.5), 391 subjects experienced the primary end-point. Patients with DM orhypovitD had similar rate of the composite end-point. Patients with only hypovitD or DM did notdiffer regarding components of composite end-point (angina p = 0.97, HF p = 0.29, mortality p = 0.62).DM and VitD deficiency had similarly adjusted risks for primary end-point (HR 1.3, 95%CI 1.05-1.61; HR 1.3, 95% CI 1.04-1.64). The adjusted HR for primary composite end-point for patients withhypovitD and DM was 1.69 (95%CI 1.25-2.29, p = 0.001) in comparison to patients with neitherhypoD nor DM. In conclusion, DM and hypovitD, individually and synergistically, are associatedwith a worse outcome after MI.

Bone health and hyperglycemia in pediatric populations

The impact of prediabetes and diabetes on skeletal health in the context of increased risk of fragility fractures in adults has been studied recently. However, the prevalence of diabetes, overweight, and obesity have also increased in younger subjects. Current data concerning bone metabolism based on assessment of markers for bone turnover and of bone quality in diabetes patients in diverse age groups appears to be inconsistent. This review synthesizes the current data on the assessment of bone turnover based on the use of circulating bone markers recommended by international organizations; the effects of age, gender, and other factors on the interpretation of the data; and the effects of type 1 and type 2 diabetes as well as hyperglycemia on bone quality and turnover with particular emphasis on the pediatric population. Early intervention in the pediatric population is necessary to prevent the progression of metabolic disturbances that accompany prediabetes and diabetes in the context of common low vitamin D status that may interfere with bone growth.

Association Between Vitamin D Status and Diabetic Complications in Patients With Type 2 Diabetes Mellitus: A Cross-Sectional Study in Hunan China

Background: Vitamin D status has been linked to diabetes-related complications due to multiple extraskeletal effects. We aimed to investigate the association between vitamin D deficiency (VDD) and diabetic vascular complications, including diabetic retinopathy (DR), diabetic kidney disease (DKD), and diabetic foot ulcers (DFU). Methods: A total of 4,284 Chinese patients with type 2 diabetic mellitus (T2DM) were enrolled into the cross-sectional study. VDD was defined as serum 25-hydroxyvitamin D <50 nmol/L. Demographic data, physical measurements, laboratory measurements, comorbidities, and related medications were collected and analyzed by VDD status. Poisson regression with robust variance estimation and binary logistic regression were performed to explore the relationship between VDD and diabetic complications. Results: The prevalence of VDD, DR, DKD, DFU accounted to 71.7% (95% confidence intervals [CI]: 70.3-73.0%), 28.5% (95% CI: 27.2-29.9%), 28.2% (95% CI: 26.8-29.5%), and 5.7% (95% CI: 5.1-6.5%), respectively. The prevalence ratios (95% CI) for DR and DKD by VDD status, adjusted for demographics, physical measurements, laboratory measurements, related complications, and comorbidities, and medications, were 1.093 (0.983-1.215) and 1.041 (0.937-1.156), respectively. The odds ratio (95% CI) for DFU by VDD status was 1.656 (1.159-2.367) in the final adjusted model. Meanwhile, the prevalence of VDD was significantly higher in patients with DFU compared with patients without DFU. Conclusions: The present study firstly indicated that VDD was significantly associated with a higher prevalence of DFU among Chinese T2DM patients. The association between VDD status and DR or DKD was not significant when adjusting for all potential covariates. Vitamin D screening or supplementation may be beneficial to prevent DFU and improve the prognosis of T2DM patients.

Shehata M, M. El-Kassas G, H. Mostafa H, M. Galal E, Refat El-Zayat S, Abd EL Ghaffar Mohammed3 N. Bone Health in Relation to Vitamin-D Status and Serum Adipokines in Obese Egyptian Children

Childhood obesity has been linked to an increase in fracture risk, so the impact of obesity on bone metabolism is becoming a focus of attention to identify factors that may affect bone health in obese children. Therefore, this study aimed to examine the association between serum 25-Hydroxy vitamin D [25(OH) D], adipokines and bone status in obese children. This case control study was executed in the Child Health Clinic in Medical and Scientific Centre of Excellence, National Research Centre (NRC), 100 obese and 80 non-obese age- and sex-matched children were enrolled in our study with mean age of (10.12±2.34 & 9.62±1.67 years) respectively. Anthropometric measurements, femoral neck bone mineral density (BMD) and its Z-score, bone mineral content (BMC) were measured using dual-energy X-ray absorptiometry (DXA) in relation to body weight (kg), we also determined serum 25(OH) D, adiponectin, leptin and lipid profile. HOMA-IR was calculated to assess insulin resistance. It was found that BMC and BMD Z-score adjusted for weight were significantly lower in obese children as compared to controls (all p<0.05). Obese children had lower levels of 25(OH) D and adiponectin (P<0.01), while higher levels of leptin, total cholesterol (TC) and triglycerides (TG) compared to controls (P<0.01). Both BMC and BMD Z-score showed positive association with 25(OH) D and adiponectin (P<0.01) and negative association with HOMA-IR, TG and TC (P<0.05). Linear regression analysis showed that 25(OH) D was the most effective factor predicting BMD Z-score and BMC in obese children. It is concluded that, obesity is negatively related to bone health in childhood. Those obese children are at increased risk for vitamin D insufficiency, which shows an obvious relationship to lower bone mass, raising the question of supplementation to prevent the deleterious effect of its deficiency on bones and reducing future risk of fracture and osteoporosis.

Type 2 Diabetes Mellitus, Insulin Resistance, and Vitamin D

PURPOSE OF REVIEW

There is a growing, largely inconsistent, literature on the role of vitamin D in association with type 2 diabetes, insulin resistance/insulin secretion, glycemic indices, and complications of type 2 diabetes. Pathophysiologic, bystander, preventive, and treatment roles of vitamin D have all been proposed. In this focused review, we attempt to organize and clarify our current information in this area.

RECENT FINDINGS

Clinical study interpretation is difficult because of variability in dosage, dosage form, study duration, and populations studied, as well as recently reported normal human polymorphisms in vitamin D synthesis and catabolism, vitamin D-binding protein, and vitamin D receptors in addition to a host of potential epigenetic confounders. Low vitamin D status appears to be associated with type 2 diabetes and most other insulin resistance disorders reported to date. The extraskeletal benefits of supplementation/repletion in these disorders in our species, with a few highlighted exceptions, remain to be established. This focused review attempts to summarize our current knowledge in this burgeoning area through a review of key meta-analyses, observational studies, randomized control trials, and Mendelian randomization studies and will hopefully serve as a guide to indicate future research directions and current best practice.

Evaluation of the relationship between microalbuminuria and 25-(OH) vitamin D levels in patients with type 2 diabetes mellitus

BACKGROUND

25-(OH) vitamin D (VD) deficiency has been described as potential risk factor for the development of diabetes in many epidemiological studies. 25-(OH) VD deficiency and insulin resistance associated with this deficiency are common findings in patients with type 2 diabetes mellitus. The objective of this study is to evaluate the relationship between 25-(OH) VD levels and microalbuminuria.

METHODS

The patients with type 2 diabetes mellitus aged between 40 and 65 years, who were admitted to the diabetes outpatient clinics of our hospital, were evaluated in two different groups. The first group consisted of 119 patients with insufficient 25-(OH) VD levels (10-30 ng/mL) and the second group consisted of 121 patients with 25-(OH) VD deficiency (≤10 ng/mL). The relationship between 25-(OH) VD levels and the level of microalbuminuria was evaluated in the two groups.

RESULTS

The mean 25-(OH) VD level was 11.5 ng/mL and the mean HbA1c level was 9.1%. When the patient groups were evaluated according to 25-(OH) VD levels, HbA1c values were significantly higher in patients with a 25-(OH) VD level of 10 ng/mL or lower (p = .039). 25-(OH) VD levels were not significantly different between patients with different stages of renal failure (p = .119), whereas the level of microalbuminuria was significantly different (p = .030).

CONCLUSIONS

This study found that the level of microalbuminuria was significantly higher in patients with 25-(OH) vitamin D deficiency compared to patients with 25-(OH) VD insufficiency.

Association of vitamin D status and the risk of cardiovascular disease as assessed by various cardiovascular risk scoring systems in patients with type 2 diabetes mellitus

OBJECTIVE

The aim of the present study was to evaluate the relationship between vitamin D (25[OH]D) status and the risk of cardiovascular disease as assessed by various cardiovascular risk scoring systems such as QRISK2, BNF, ASSING, SCORE, and Framingham in patients with type 2 diabetes mellitus(T2DM).

METHODS

The study included 108 patients with vitamin D insufficiency (25[OH]D ≥ 10-30 ng/mL) and 100 patients with vitamin D deficiency (25[OH]D < 10 ng/mL), who were admitted to the diabetes outpatient clinics due to T2DM and who were aged 45-65 years. QRISK2, BNF, ASSING, SCORE, and Framingham were calculated and compared between the two groups.

RESULTS

HbA1c levels were significantly higher in patients with vitamin D deficiency. Patients with vitamin D deficiency had significantly higher Framingham risk score (p < .001) and significantly lower BNF score (p < .001), whereas other scores did not significantly differ between the groups. There was a moderate, statistically significant correlation between 25[OH]D levels and Framingham risk score in negative direction (r = 0.537) and a weak but statistically significant correlation between 25[OH]D levels and BNF score (r = 0.295). 25[OH]D levels were significantly higher and HbA1c levels were significantly lower in patients with Framingham cardiovascular risk score ≤10%.

CONCLUSION

We found a close relationship with Framingham cardiovascular risk score in diabetic patients with very low serum vitamin D levels. Cardiovascular risk as assessed by the Framingham's scale increases with decreasing 25[OH]D levels. BNF score was negatively correlated with 25[OH]D levels.

Vitamin D deficiency increases risk of nephropathy and cardiovascular diseases in Type 2 diabetes mellitus patients

Background:

Vitamin D (VD) deficiency is associated with insulin function and secretion. It is linked with diabetes mellitus (DM) progression, and complications were also recorded. Therefore, the current study aimed to investigate serum VD level in Type 2 DM (T2DM) patients and its association with diabetic nephropathy and cardiovascular diseases (CVD).

Materials and Methods:

In this cross-sectional study, 205 patients with Type 2 diabetes age ranged from 39 to 75 years old were enrolled. Serum VD, high-sensitivity C-reactive protein (hs-CRP), and hemoglobin A1c (HbA1c) were measured. In addition, urinary albumin:creatinine ratio (ACR) was estimated.

Results:

Patients with Type 2 diabetes had a 78.5% VD level <30 ng/m. ACR and hs-CRP levels were significantly increased in patients with diabetes with VD <30 ng/m (P = 0.011 and P = 0.008, respectively). Female had significantly lower VD level than male P < 0.001. Patients exposed to sunlight had significantly higher VD level and lower hs-CRP levels compared with less-exposed, P value (0.001 and <0.001), respectively. Exercise significantly increased VD and decreased ACR levels in DM patients, P value (0.046 and 0.002), respectively. VD was positively associated with age (r = 0.355 P = 0.040) and negatively correlate with BMI (r = −0.502 P = 0.009), duration of disease (r = −0.498 P = 0.003), ACR (r = −0.384 P = 0.015), and HbA1c (r = −0.327 P = 0.032).

Conclusion:

The evidence from this study suggest that patients with Type 2 diabetes with VD deficiency are at higher risk for developing CVD and nephropathy.

Association between serum 25-hydroxyvitamin D and diabetic kidney disease in Chinese patients with type 2 diabetes

Objective

The objective was to assess the association between 25-hydroxyvitamin D (25OHD) level and diabetic kidney disease (DKD) in Chinese patients with type 2 diabetes.

Methods

Data pertaining to 351 in-patients with type 2 diabetes were collected. Subjects were classified into three groups based on the level of urinary albumin-to-creatinine ratio (UACR). UACR < 30 mg/g was defined as normoalbuminuria, while UACR levels of 30–300 mg/g and ≥ 300 mg/g were defined as microalbuminuria and macroalbuminuria, respectively. Serum 25OHD and other clinical characteristics among various UACR groups were compared. The relationship between albuminuiria and 25OHD was analyzed.

Results

The prevalence of 25OHD insufficiency in the microalbuminuria group was significantly higher than that in the normoalbuminuria group (25.1% vs. 19.6%; P < 0.05); patients with macroalbuminuria had the highest prevalence of 25OHD deficiency (37.8%; P < 0.01 versus normoalbuminuria). Logistic regression analyses demonstrated that low 25OHD levels were associated with DKD [odds ratio (OR) = 1.51, 95% confidence interval (CI) 1.16–1.97). The association was more robust after adjusting for sex, hypertension, increased systolic blood pressure, glycemic status, and hyperuricemia (OR = 1.62, 95% CI 1.19–2.20).

Conclusions

The prevalence of vitamin D insufficiency/deficiency in patients with albuminuria was overtly higher than that in patients without albuminuria among Chinese adults with type 2 diabetes. Vitamin D insufficiency/deficiency was independently associated with DKD in type 2 diabetes.

Comprehensive Review on Diabetes Associated Cardiovascular Complications - The Vitamin D Perspective

Vitamin D, a steroid hormone is primarily known for its role in calcium and bone mineral homeostasis. Over the years, vitamin D has been implicated in various non-skeletal diseases. The extraskeletal phenomenon can be attributed to the presence of vitamin D receptors (VDRs) in almost all cells and identification of 1-α hydroxylase in extrarenal tissues. The vitamin D deficiency (VDD) pandemic was globally reported with increasing evidence and paralleled the prevalence of diabetes, obesity and cardiovascular diseases (CVDs). A dependent link was proposed between hypovitaminosis D glycemic status, insulin resistance and also the other major factors associated with type 2 diabetes leading to CVDs. Insulin resistance plays a central role in both type 2 diabetes and insulin resistance syndrome. These 2 disorders are associated with distinct etiologies including hypertension, atherogenic dyslipidemia, and significant vascular abnormalities that could lead to endothelial dysfunction. Evidence from randomised clinical trials and meta-analysis, however, yielded conflicting results. This review summarizes the role of vitamin D in the regulation of glucose homeostasis with an emphasis on insulin resistance, blood pressure, dyslipidaemia, endothelial dysfunction and related cardiovascular diseases and also underline the plausible mechanisms for all the documented effects.

Non-traditional risk factors for coronary calcification and its progression in patients with type 2 diabetes: The impact of postprandial glycemia and fetuin-A

Objective

This study was performed to assess the impact of risk factors on the presence and progression of coronary calcification in patients with type 2 diabetes.

Methods

We prospectively enrolled 45 patients without cardiovascular or kidney disease. Coronary calcification was measured with multidetector computed tomography at baseline and 18 months. We also measured blood pressure; body mass index; serum levels of calcium, phosphate, and 25-hydroxyvitamin D; mineral bone density; and levels of alkaline phosphatase, parathormone, fetuin-A, high-sensitivity C-reactive protein, fibrinogen, albumin, homocysteine, lipids, HbA1c, and average preprandial and postprandial blood glucose at 18 months. Information about severe hypoglycemia and smoking was recorded. Spearman’s correlation coefficients were calculated. Multiple linear regression was used for the multivariate analysis.

Results

The median baseline calcium score was 63, and that at 18 months was 100. In the univariate analysis, albumin was significantly correlated with the baseline calcium score. Fetuin-A and postprandial glycemia were correlated with calcium score progression. In the multivariate model, postprandial glycemia and fetuin-A were independently associated with calcium score progression.

Conclusions

Fetuin-A and postprandial glycemia influence coronary calcification progression in patients with type 2 diabetes. The absence of some correlations could be due to pharmacological treatments for cardiovascular risk reduction.

Recent Advances in Formulation Strategies for Efficient Delivery of Vitamin D

Deficiency of vitamin D is a global concern affecting a huge number of human populations. This deficiency has a serious impact on human health not only affecting bone mineral density but also becoming the reason for cardiovascular disorders, infectious diseases, autoimmune diseases and cancers. Exposure to sunlight is the major source of vitamin D, but due to the present day-to-day lifestyle of working in a shade arouses the need for exogenous sources of vitamin D. Ergocalciferol (vitamin D2) and cholecalciferol (vitamin D3) are the two major forms of vitamin D, which are hydrophobic in nature and highly susceptible to environmental conditions, like temperature and light. Therefore, novel drug delivery systems could be explored for efficient delivery of vitamin D. In this review, a brief account of vitamin D is provided followed by a detailed description of recent advances in various delivery systems, including solid lipid nanoparticles, nanoemulsion, self-emulsifying drug delivery systems, polymeric nanoparticles and solid dispersion, for the efficient delivery of vitamin D.

Vitamin D and metabolic disturbances in polycystic ovary syndrome (PCOS): A cross-sectional study

OBJECTIVE

To compare vitamin D status in women with PCOS versus fertile women and subsequently evaluate the association between vitamin D status and metabolic disturbances in PCOS women.

METHODS

We conducted a cross-sectional comparison study of 639 women with PCOS and 449 fertile women. Serum 25-hydroxyvitamin D (25(OH)D) was stratified into a severe deficient (< 25 nmol/l), insufficient (25-50 nmol/l), moderate (50-75 nmol/l) and adequate (> 75 nmol/l) status. The main outcome measures were the difference in vitamin D status between PCOS and fertile women, and the association between serum 25(OH)D and metabolic disturbances in PCOS women only.

RESULTS

Serum 25(OH)D was significantly lower in PCOS women compared to fertile controls (mean 25(OH)D of 49.0 nmol/l versus 64.5 nmol/l). An adjusted significant difference was seen between serum 25(OH)D and homeostasis model assessment (HOMA-IR) (β = 0.76; 95% CI: 0.63-0.91; p < 0.01), HDL-cholesterol (β = 0.20; 95% CI: 0.05-0.60, p < 0.01) and apolipoprotein A1 (β = 26.2; 95% CI: 7.5-45.0, p < 0.01) between the highest vitamin D group compared to the lowest vitamin D group.

CONCLUSIONS

This study demonstrates that women with PCOS have a significantly lower serum 25(OH)D compared to fertile controls. A compromised vitamin D status in PCOS women is associated with a higher HOMA-IR and an unfavourable lipid profile. Large randomized controlled trials are necessary to explore the causality of this linkage.

Variability in genes regulating vitamin D metabolism is associated with vitamin D levels in type 2 diabetes

Mortality rate is increased in type 2 diabetes (T2D). Low vitamin D levels are associated with increased mortality risk in T2D. In the general population, genetic variants affecting vitamin D metabolism (DHCR7 rs12785878, CYP2R1 rs10741657, GC rs4588) have been associated with serum vitamin D. We studied the association of these variants with serum vitamin D in 2163 patients with T2D from the “Sapienza University Mortality and Morbidity Event Rate (SUMMER) study in diabetes”. Measurements of serum vitamin D were centralised. Genotypes were obtained by Eco™ Real-Time PCR. Data were adjusted for gender, age, BMI, HbA1c, T2D therapy and sampling season.

DHCR7 rs12785878 (p = 1 x 10–4) and GC rs4588 (p = 1 x 10–6) but not CYP2R1 rs10741657 (p = 0.31) were significantly associated with vitamin D levels.

One unit of a weighted genotype risk score (GRS) was strongly associated with vitamin D levels (p = 1.1 x 10–11) and insufficiency (<30 ng/ml) (OR, 95%CI = 1.28, 1.16–1.41, p = 1.1 x 10–7).

In conclusion, DHCR7 rs12785878 and GC rs4588, but not CYP2R1 rs10741657, are significantly associated with vitamin D levels. When the 3 variants were considered together as GRS, a strong association with vitamin D levels and vitamin D insufficiency was observed, thus providing robust evidence that genes involved in vitamin D metabolism modulate serum vitamin D in T2D.

Vitamin D insufficiency predicts mortality among older men, but not women: A nationwide retrospective cohort from Thailand

AIM

Previous studies on the association between low vitamin D level and increased mortality mainly came from high-income countries. The primary objective of the present study was to examine the effect of sex on the association between 25-hydroxyvitamin D₂ and D₃ and mortality among community-dwelling older people in Thailand.

METHODS

A cohort of individuals aged ≥60 years from the Thai 4th National Health Examination Survey carried out in 2008 were followed and linked to a vital registry in 2015. Data regarding comorbid diseases, physical activity and serum vitamin D were obtained at the baseline assessment. Factors associated with all-cause mortality were determined using Cox proportional hazards models.

RESULTS

A total of 1268 participants with a median age of 74.0 years (interquartile range 67.0-81.0) were included. The prevalence of vitamin D insufficiency was 24.5% and 43.9% in men and women, respectively. Vitamin D insufficiency was significantly associated with all-cause mortality only among men (adjusted HR 1.77, 95% CI 1.25-2.51), but not women. Analysis of 25-hydroxyvitamin D3 divided into tertiles also showed an association with an adjusted HR of 1.83 (95% CI 1.23-2.72) for the lowest tertile in men. Diabetes was an effect modifier for low serum vitamin D and male sex, with HR 3.34 (95% CI 1.76-6.33, P < 0.001) in diabetic men with vitamin D insufficiency.

CONCLUSIONS

Low serum vitamin D is an independent risk factor for increased mortality in community-dwelling Thai older men. Further randomized controlled study to investigate the benefit of vitamin D3 supplementation in older persons, particularly men, is warranted. Geriatr Gerontol Int 2018; 18: 1585-1590.

Vitamin D Deficiency in Chronic Kidney Disease: Recent Evidence and Controversies

Vitamin D (VD) is a pro-hormone essential for life in higher animals. It is present in few types of foods and is produced endogenously in the skin by a photochemical reaction. The final step of VD activation occurs in the kidneys involving a second hydroxylation reaction to generate the biologically active metabolite 1,25(OH)₂-VD. Extrarenal 1α-hydroxylation has also been described to have an important role in autocrine and paracrine signaling. Vitamin D deficiency (VDD) has been in the spotlight as a major public healthcare issue with an estimated prevalence of more than a billion people worldwide. Among individuals with chronic kidney disease (CKD), VDD prevalence has been reported to be as high as 80%. Classically, VD plays a pivotal role in calcium and phosphorus homeostasis. Nevertheless, there is a growing body of evidence supporting the importance of VD in many vital non-skeletal biological processes such as endothelial function, renin-angiotensin-aldosterone system modulation, redox balance and innate and adaptive immunity. In individuals with CKD, VDD has been associated with albuminuria, faster progression of kidney disease and increased all-cause mortality. Recent guidelines support VD supplementation in CKD based on extrapolation from cohorts conducted in the general population. In this review, we discuss new insights on the multifactorial pathophysiology of VDD in CKD as well as how it may negatively modulate different organs and systems. We also critically review the latest evidence and controversies of VD monitoring and supplementation in CKD patients.

The Effect of Vitamin D Supplementation on Glycemic Control in Type 2 Diabetes Patients: A Systematic Review and Meta-Analysis

Observational studies have indicated an inverse association between vitamin D levels and the risk of diabetes, yet evidence from population interventions remains inconsistent. PubMed, EMBASE, Cochrane Library and ClinicalTrials.gov were searched up to September 2017. Data from studies regarding serum 25(OH)D, fasting blood glucose (FBG), hemoglobin A1c (HbA1c), fasting insulin and homeostasis model assessment of insulin resistance (HOMA-IR) were pooled. Twenty studies (n = 2703) were included in the meta-analysis. Vitamin D supplementation resulted in a significant improvement in serum 25(OH)D levels (weighted mean difference (WMD) = 33.98; 95%CI: 24.60-43.37) and HOMA-IR (standardized mean difference (SMD) = -0.57; 95%CI: -1.09~-0.04), but not in other outcomes. However, preferred changes were observed in subgroups as follows: short-term (WMD_FBG = -8.44; 95%CI: -12.72~-4.15), high dose (WMD_FBG = -8.70; 95%CI: -12.96~-4.44), non-obese (SMD_{Fasting insulin} = -1.80; 95%CI: -2.66~-0.95), Middle Easterners (WMD_FBG = -10.43; 95%CI: -14.80~-6.06), baseline vitamin D deficient individuals (WMD_FBG = -5.77; 95%CI: -10.48~-1.05) and well-controlled HbA1c individuals (WMD_FBG = -4.09; 95%CI: -15.44~7.27). Vitamin D supplementation was shown to increase serum 25(OH)D and reduce insulin resistance effectively. This effect was especially prominent when vitamin D was given in large doses and for a short period of time, and to patients who were non-obese, Middle Eastern, vitamin D deficient, or with optimal glycemic control at baseline.

Vitamin D deficiency is associated with poorer satisfaction with diabetes-related treatment and quality of life in patients with type 2 diabetes: a cross-sectional study

BACKGROUND

In this cross-sectional study, we assessed the possible association of vitamin D deficiency with self-reported treatment satisfaction and health-related quality of life in patients with type 2 diabetes.

METHODS

We performed a sub-analysis of a previous study and included a total of 292 type 2 diabetic patients. We evaluated treatment satisfaction and health-related quality of life through specific tools: the Diabetes Treatment Satisfaction Questionnaire and the Audit of Diabetes-Dependent Quality of Life. Vitamin D deficiency was defined as 25 (OH) D serum levels < 15 ng/mL.

RESULTS

Multivariable linear regression models were used to estimate the relationship of vitamin D deficiency with both outcomes once adjusted for self-reported patient characteristics. Vitamin D deficiency was significantly associated with the final score of the Diabetes Treatment Satisfaction Questionnaire and the single "diabetes-specific quality of life" dimension of the Audit of Diabetes-Dependent Quality of Life (p = 0.0198 and p = 0.0070, respectively). However, lower concentrations of 25-OH vitamin D were not associated with the overall quality of life score or the perceived frequency of hyperglycaemia and hypoglycaemia.

CONCLUSIONS

Our study shows the association between vitamin D deficiency and both the self-reported diabetes treatment satisfaction and the diabetes-specific quality of life in patients with type 2 diabetes.

Vitamin D levels in subjects with or without chronic kidney disease among Veterans with diabetes in North East United States

AIM

To evaluate the prevalence of vitamin D deficiency and its relation to diabetes and kidney disease in Veterans residing in the North East United States (VISN 2).

METHODS

In this retrospective study, we used data from the computerized patient record system at Stratton Veterans Administration Medical Center at Albany, NY (VHA) for those patients who had 25-hydroxyvitamin D levels and 1,25 (OH) vitamin D levels measured between 2007 and 2010. We collected demographic information including age, sex, body mass index and race; clinical data including diabetes, hypertension and CAD; and laboratory data including calcium, creatinine and parathyroid hormone (PTH) (intact). Vitamin D deficiency is defined as a serum 25-hydroxyvitamin D level of less than 20 ng/mL (50 nmol/L), and insufficiency is defined as a serum 25-hydroxyvitamin D level of 20 to 30 ng/mL (50 to 75 nmol/L).

RESULTS

Data was available for approximately 68000 subjects. We identified 64144 subjects for analysis after exclusion of duplicates. Among them, 27098 had diabetes. The mean age of subjects with diabetes was 68 ± 11 with a mean body mass index (BMI) of 32 ± 7 and duration of diabetes of 5.6 ± 3.2 years. The mean 25 (OH) vitamin D level among subjects with diabetes was 27 ± 11.6. There was no significant difference in 25 (OH) vitamin D levels between subjects with diabetes and glomerular filtration rate (e-GFR) < 60 compared to those with e-GFR ≥ 60. As expected, subjects with e-GFR < 60 had significantly lower 1,25 (OH) vitamin D levels and significantly elevated PTH-intact. Of the 64144 subjects, 580 had end-stage renal disease. Of those, 407 had diabetes and 173 did not. Vitamin D levels in both groups were in the insufficiency range and there was no significant difference irrespective of presence or absence of diabetes. Subjects with vitamin D levels less than 20 ng/mL had a higher BMI and elevated PTH, and higher HbA1C levels compared to those with vitamin D levels more than 20 ng/mL.

CONCLUSION

We conclude that we need to keep a close eye on vitamin D levels in subjects with mild chronic kidney disease as well as those with moderate control of diabetes.

Vitamin D, sub-inflammation and insulin resistance. A window on a potential role for the interaction between bone and glucose metabolism

Vitamin D is a key hormone involved in the regulation of calcium/phosphorous balance and recently it has been implicated in the pathogenesis of sub-inflammation, insulin resistance and obesity. The two main forms of vitamin D are cholecalciferol (Vitamin D3) and ergocalciferol (Vitamin D2): the active form (1,25-dihydroxyvitamin D) is the result of two hydroxylations that take place in liver, kidney, pancreas and immune cells. Vitamin D increases the production of some anti-inflammatory cytokines and reduces the release of some pro-inflammatory cytokines. Low levels of Vitamin D are also associated with an up-regulation of TLRs expression and a pro-inflammatory state. Regardless of the effect on inflammation, Vitamin D seems to directly increase insulin sensitivity and secretion, through different mechanisms. Considering the importance of low grade chronic inflammation in metabolic syndrome, obesity and diabetes, many authors hypothesized the involvement of this nutrient/hormone in the pathogenesis of these diseases. Vitamin D status could alter the balance between pro and anti-inflammatory cytokines and thus affect insulin action, lipid metabolism and adipose tissue function and structure. Numerous studies have shown that Vitamin D concentrations are inversely associated with pro-inflammatory markers, insulin resistance, glucose intolerance and obesity. Interestingly, some longitudinal trials suggested also an inverse association between vitamin D status and incident type 2 diabetes mellitus. However, vitamin D supplementation in humans showed controversial effects: with some studies demonstrating improvements in insulin sensitivity, glucose and lipid metabolism while others showing no beneficial effect on glycemic control and on inflammation. In conclusion, although the evidences of a significant role of Vitamin D on inflammation, insulin resistance and insulin secretion in the pathogenesis of obesity, metabolic syndrome and type 2 diabetes, its potential function in treatment and prevention of type 2 diabetes mellitus is unclear. Encouraging results have emerged from Vitamin D supplementation trials on patients at risk of developing diabetes and further studies are needed to fully explore and understand its clinical applications.

Changes in plasma concentrations of 25-hydroxyvitamin D and 1,25-dihydroxyvitamin D during pregnancy: a Brazilian cohort

PURPOSE

To characterize the physiological changes in 25-hydroxyvitamin D [25(OH)D] and 1,25-dihydroxyvitamin D [1,25(OH)₂D] throughout pregnancy.

METHODS

Prospective cohort of 229 apparently healthy pregnant women followed at 5th-13th, 20th-26th, and 30th-36th gestational weeks. 25(OH)D and 1,25(OH)₂D concentrations were measured by LC-MS/MS. Statistical analyses included longitudinal linear mixed-effects models adjusted for parity, season, education, self-reported skin color, and pre-pregnancy BMI. Vitamin D status was defined based on 25(OH)D concentrations according to the Endocrine Society Practice Guideline and Institute of Medicine (IOM) for adults.

RESULTS

The prevalence of 25(OH)D <75 nmol/L was 70.4, 41.0, and 33.9%; the prevalence of 25(OH)D <50 nmol/L was 16.1, 11.2, and 10.2%; and the prevalence of 25(OH)D <30 nmol/L was 2, 0, and 0.6%, at the first, second, and third trimesters, respectively. Unadjusted analysis showed an increase in 25(OH)D (β = 0.869; 95% CI 0.723-1.014; P < 0.001) and 1,25(OH)₂D (β = 3.878; 95% CI 3.136-4.620; P < 0.001) throughout pregnancy. Multiple adjusted analyses showed that women who started the study in winter (P < 0.001), spring (P < 0.001), or autumn (P = 0.028) presented a longitudinal increase in 25(OH)D concentrations, while women that started during summer did not. Increase of 1,25(OH)₂D concentrations over time in women with insufficient vitamin D (50-75 nmol/L) at baseline was higher compared to women with sufficient vitamin D (≥75 nmol/L) (P = 0.006).

CONCLUSIONS

The prevalence of vitamin D inadequacy varied significantly according to the adopted criteria. There was a seasonal variation of 25(OH)D during pregnancy. The women with insufficient vitamin D status present greater longitudinal increases in the concentrations of 1,25(OH)₂D in comparison to women with sufficiency.

Association between serum 25(OH)D3 and cardiovascular morbidity and mortality in people with Type 2 diabetes: a community-based cohort study

AIM

We aimed to explore the association between vitamin D and cardiovascular morbidity and mortality in people with Type 2 diabetes recruited from a community-based study because there is limited and inconsistent research of this group.

METHODS

A prospective community-based cohort study among people aged 55-66 years with Type 2 diabetes as part of The Cardiovascular Risk in Type 2 Diabetes - A Prospective Study in Primary Care (CARDIPP). We analysed serum 25-hydroxyvitamin D₃ [25(OH)D₃ ] at baseline. Cox regression analyses were used to calculate hazard ratios (HR) for the first myocardial infarction, stroke or cardiovascular mortality according to 25(OH)D₃ .

RESULTS

We examined 698 people with a mean follow-up of 7.3 years. Serum 25(OH)D₃ was inversely associated with the risk of cardiovascular morbidity and mortality: HR 0.98 [95% confidence interval (CI) 0.96 to 0.99, P = 0.001]. Compared with the fourth quartile (Q4) [25(OH)D₃ > 61.8 nmol/l], HR (with 95% CI) was 3.46 (1.60 to 7.47) in Q1 [25(OH)D₃ < 35.5 nmol/l] (P = 0.002); 2.26 (1.01 to 5.06) in Q2 [25(OH)D₃ 35.5-47.5 nmol/l] (P = 0.047); and 1.62 (0.70 to 3.76) in Q3 [25(OH)D₃ 47.5-61.8 nmol/l] (P = 0.26) when adjusting for age, sex and season. The results remained significant after adjusting also for cardiovascular risk factors, physiological variables including parathyroid hormone and previous cardiovascular disease (P = 0.027).

CONCLUSIONS

Low 25(OH)D₃ is associated with an increased risk of cardiovascular morbidity and mortality in people with Type 2 diabetes independent of parathyroid hormone. Vitamin D could be considered as a prognostic factor. Future studies are needed to explore whether vitamin D deficiency is a modifiable risk factor in Type 2 diabetes.

The Association of Vitamin D Status and Vitamin D Replacement Therapy with Glycemic Control, Serum Uric Acid Levels, and Microalbuminuria in Patients with Type 2 Diabetes and Chronic Kidney Disease

OBJECTIVE

To evaluate the relationship of vitamin D status and vitamin D replacement therapy with glycemic control, serum uric acid (SUA) levels, and microalbuminuria (MAU) in patients with type 2 diabetes (T2DM) and chronic kidney disease (CKD). Subjectsand Methods: A total of 1,463 patients with T2DM and CKD (aged 14-88 years), 927 females and 536 males, were included in this study. The serum data of 25-hydroxyvitamin D, i.e., 25(OH)D, level, SUA, hemoglobin (Hb)A1c, creatinine, estimated glomerular filtration rate, and urine albumin-to-creatinine ratio (UACR) were obtained from the medical records. The Mann-Whitney U test, the χ2 test, the Mantel-Haenszel test, and linear regression models were used for data analysis.

RESULTS

Vitamin D deficiency and insufficiency were evident in 770 (52.0%) and 357 (24.0%) patients, respectively. Median HbA1c levels (7.3 [IQR 3.9] vs. 6.5 [IQR 2.3]%; p < 0.01) were significantly higher in patients deficient in vitamin D than in those with a normal vitamin D status. A significantly low level of vitamin D was noted with a high UACR (β -0.01; 95% CI -0.01 to -0.001; p = 0.017) and HbA1c (β -1.1; 95% CI -1.6 to -0.6; p < 0.001), but with low levels of SUA (β 1.3; 95% CI 0.5-2.2; p = 0.002). Vitamin D replacement was associated with a significantly low level of HbA1c (7.4 [2.7] vs. 6.7 [1.9]%; p < 0.001].

CONCLUSION

In this study, there was a high prevalence of hypovitaminosis D among T2DM patients with CKD, with a higher UACR, higher HbA1c, and lower SUA being noted as playing a role in predicting a decrease in vitamin D levels and potential benefits of vitamin D replacement therapy on glycemic control in T2DM management.

MANAGEMENT OF ENDOCRINE DISEASE: The effect of vitamin D supplementation on glycaemic control in patients with type 2 diabetes mellitus: a systematic review and meta-analysis

OBJECTIVE

Epidemiologic studies suggest that vitamin D status plays a role in glycaemic control in patients with type 2 diabetes. However, intervention studies yielded inconsistent results. The aim of this study is to systematically review the effect of vitamin D supplementation on glycaemic control in patients with type 2 diabetes.

METHODS

Systematic review and meta-analysis. We searched Medline, Embase and the Cochrane Library for RCTs examining the effect of vitamin D supplementation on glycaemic control in patients with type 2 diabetes. A random-effects model meta-analysis was performed to obtain a summarized outcome of vitamin D supplementation on HbA_1c, fasting glucose and homeostasis model assessment - insulin resistance (HOMA-IR).

RESULTS

Twenty-three RCTs were included in this systematic review representing a total of 1797 patients with type 2 diabetes. Mean (± s.d.) change in serum 25-hydroxyvitamin D varied from 1.8 ± 10.2 nmol/L to 80.1 ± 54.0 nmol/L. Nineteen studies included HbA_1c as outcome variable. Combining these studies no significant effect in change of HbA_1c was seen after vitamin D intervention compared with placebo. A significant effect of vitamin D supplementation was seen on fasting glucose in a subgroup of studies (n = 4) with a mean baseline HbA_1c ≥ 8% (64 mmol/mol) (standardized difference in means: 0.36; 95% CI: 0.12-0.61, P = 0.003).

CONCLUSIONS

Current evidence of RCTs does not support short-term vitamin D supplementation in a heterogeneous population with type 2 diabetes. However, in patients with poorly controlled diabetes, a favourable effect of vitamin D is seen on fasting glucose.

Vitamin D Deficiency Is Associated with Severity of Acute Coronary Syndrome in Patients with Type 2 Diabetes and High Rates of Sun Exposure

BACKGROUND

Vitamin D deficiency has been associated with cardiovascular risk factors, including type 2 diabetes mellitus (T2DM). Evidence shows that patients with low serum 25-hydroxyvitamin D (25OHD) concentrations have a higher risk of developing coronary artery disease.

OBJECTIVE

The objective of this study was to assess vitamin D as a predictor of the severity in diabetics with acute coronary syndrome (ACS).

METHODS

A total of 166 patients were diagnosed with ACS. Serum 25OHD concentrations were analyzed, and risk factors for ACS were evaluated.

RESULTS

Patients diagnosed as having acute myocardial infarction with elevation of the ST segment had a higher rate of 25OHD, <20 ng/mL compared to ≥30 ng/mL (47.8% × 13.4%, P = 0.03). Diabetics with vitamin D deficiency had more multivessel lesions in the coronary angiography than non-diabetics (69% × 31.8%, P = 0.007). After adjustments for confounders, serum 25OHD remained associated with more severe disease.

CONCLUSION

Vitamin D deficiency is associated with more severe ACS and is a predictor of more extensive coronary lesions in patients with T2DM.