Association of 25-hydroxyvitamin D with type 2 diabetes among patients undergoing coronary angiography: cross-sectional findings from the LUdwigshafen Risk and Cardiovascular Health (LURIC) Study

Association between vitamin D deficiency and lipid profiles in overweight and obese adults: a systematic review and meta-analysis

OBJECTIVE

The association between vitamin D deficiency and lipid profiles in adults with overweight or obesity remains unclear and inconsistent. The aim of our study was to determine the relationship between lipid profiles and vitamin D deficiency in the overweight and obese adults.

METHODS

Four databases, including PubMed, the Web of Science, EMBASE and the Cochrane Library, were used to identify all studies on vitamin D status and lipid levels, including the serum levels of triglycerides (TGs), total cholesterol (TC), low-density lipoprotein cholesterol (LDL), and high-density lipoprotein cholesterol (HDL). The Weighted mean difference (WMD) with 95% confidence intervals (CIs) using random-effects models was used to assess the association between the lipid profile and vitamin D deficiency.

RESULTS

Twenty-one articles that included a total of 7952 adults with overweight or obesity (BMI ≥ 25 kg/m2) were included. The overall results revealed that compared with the controls, individuals with vitamin D deficiency showed higher levels of TG (WMD = 15.01; 95%CI, 2.51-27.52) and TC (WMD = 8.61; 95%CI, 1.31-15.92). Moreover, vitamin D deficiency was related to an increased level of LDL (WMD = 6.12; 95%CI, 0.02-12.23). HDL level was inversely associated with the vitamin D deficiency status (WMD = -2.57; 95%CI, -4.26, -0.88).

CONCLUSIONS

Among the adults with overweight or obesity, the vitamin D deficient group displayed impaired lipid profiles, including increased TG, TC and LDL levels and reduced HDL level.

Vitamin D Metabolites: Analytical Challenges and Clinical Relevance

Recent research activities have provided new insights in vitamin D metabolism in various conditions. Furthermore, substantial progress has been made in the analysis of vitamin D metabolites and related biomarkers, such as vitamin D binding protein. Liquid chromatography tandem mass spectrometric (LC-MS/MS) methods are capable of accurately measuring multiple vitamin D metabolites in parallel. Nevertheless, only 25(OH)D and the biologically active form 1,25(OH)2D are routinely measured in clinical practice. While 25(OH)D remains the analyte of choice for the diagnosis of vitamin D deficiency, 1,25(OH)2D is only recommended in a few conditions with a dysregulated D metabolism. 24,25(OH)2D, free and bioavailable 25(OH)D, and the vitamin D metabolite ratio (VMR) have shown promising results, but technical pitfalls in their quantification, limited clinical data and the lack of reference values, impede their use in clinical practice. LC-MS/MS is the preferred method for the measurement of all vitamin D related analytes as it offers high sensitivity and specificity. In particular, 25(OH)D and 24,25(OH)2D can accurately be measured with this technology. When interpreted together, they seem to provide a functional measure of vitamin D metabolism beyond the analysis of 25(OH)D alone. The determination of VDBP, free and bioavailable 25(OH)D is compromised by unresolved analytical issues, lacking reference intervals and insufficient clinical data. Therefore, future research activities should focus on analytical standardization and exploration of their clinical value. This review provides an overview on established and new vitamin D related biomarkers including their pathophysiological role, preanalytical and analytical aspects, expected values, indications and influencing conditions.

Vitamin D Deficiency Is Inversely Associated with Homeostatic Model Assessment of Insulin Resistance

The study was conducted to comprehensively assess the association of the concentration of vitamin D in the blood and insulin resistance in non-diabetic subjects. The objective was to pool the results from all observational studies from the beginning of 1980 to August 2021. PubMed, Medline and Embase were systematically searched for the observational studies. Filters were used for more focused results. A total of 2248 articles were found after raw search which were narrowed down to 32 articles by the systematic selection of related articles. Homeostatic Model Assessment of Insulin Resistance (HOMAIR) was used as the measure of insulin resistance and correlation coefficient was used as a measure of the relationship between vitamin D levels and the insulin resistance. Risk of bias tables and summary plots were built using Revman software version 5.3 while Comprehensive meta-analysis version 3 was used for the construction of forest plot. The results showed an inverse association between the status of vitamin D and insulin resistance (r = -0.217; 95% CI = -0.161 to -0.272; p = 0.000). A supplement of vitamin D can help reduce the risk of insulin resistance; however further studies, like randomized controlled trials are needed to confirm the results.

Insulin Resistance Is Inversely Associated with the Status of Vitamin D in Both Diabetic and Non-Diabetic Populations

Vitamin D has been implicated in the regulation of glucose metabolism and insulin resistance. We designed this study to provide evidence that insulin resistance is dependent on the concentration of vitamin D in the body. Forty observational studies of both type 2 diabetes mellitus patients and healthy subjects were included in this meta-analysis. Related articles were searched from Embase, PubMed, and Medline through January 2021. Filters for search were used to obtain more focused results. We used Comprehensive Meta-Analysis Version 3 for the construction of forest plots. RevMan software version 5.3 was used to build the risk of bias tables and summary plots. The observational studies included in this systematic review and meta-analysis showed an inverse relationship of insulin resistance with the status of vitamin D both in non-diabetic (r = -0.188; 95% CI = -0.141 to -0.234; p = 0.000) and diabetic (r = -0.255; 95% CI = -0.392 to -0.107, p = 0.001) populations. From the meta-analysis we concluded that hypovitaminosis D is related to increased levels of insulin resistance in both type 2 diabetes patients and the healthy population all over the world.

Intronic Variants in OCT1 are Associated with All-Cause and Cardiovascular Mortality in Metformin Users with Type 2 Diabetes

PURPOSE

Organic cation transporters (Octs) use cations like endogenous compounds, toxins, and drugs, such as metformin, as substrates. Therefore, these proteins determine the pharmacokinetics and -dynamics of metformin and thus its efficacy. Of note, metformin is today the most commonly used pharmaceutical in the treatment of type 2 diabetes (T2DM) with nevertheless a great variability in clinical response, which attributes to genetic variances. The aim of this study was to determine the influence of intronic OCT1 SNPs on prevalence of all-cause and cardiovascular death.

PATIENTS AND METHODS

Genotypes of 27 intronic SNPs in OCT1 were investigated in the LURIC study, a prospective cohort of 3316 participants scheduled for coronary angiography. We investigated whether these variants were associated with all-cause and cardiovascular death in 73 individuals with T2DM under metformin therapy, in individuals without diabetes, individuals with T2DM and individuals with T2DM without metformin therapy.

RESULTS

In a multivariate Cox regression analysis adjusted for classical cardiovascular risk factors, 4 intronic OCT1 SNPs were significantly associated with all-cause and cardiovascular mortality in individuals with T2DM on metformin therapy.

CONCLUSION

According to their OCT1 genotype, some individuals with T2DM on metformin therapy might be prone to an increased risk of cardiovascular death.

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

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

High Dose Supplementation of Vitamin D Affects Measures of Systemic Inflammation: Reductions in High Sensitivity C-Reactive Protein Level and Neutrophil to Lymphocyte Ratio (NLR) Distribution

The prevalence of Vitamin D deficiency is increasing worldwide, which has be shown to be associated with increased risk of cardiovascular disease (CVD), autoimmune disease, and metabolic syndrome. These conditions are also associated with a heightened state of inflammation. The aim of the current study was to evaluate the effect of vitamin D supplementation on serum C-Reactive Protein (CRP) level and Neutrophil-to-lymphocyte ratio (NLR) distribution in a large cohort of adolescent girls. A total of 580 adolescent girls were recruited follow by evaluation of CRP and hematological parameters before and after supplementation with vitamin D supplements as 9 of 50000 IU cholecalciferol capsules for 9 weeks taken at weekly intervals. At baseline, serum hs-CRP level was 0.9 (95%CI: 0.5-1.8), while this value after intervention was reduced to 0.8 (95%CI: 0.3-1.6; P = 0.007). Similar results were also detected for NLR (e.g., NLR level was 1.66 ± 0.72 and 1.53 ± 0.67, P = 0.002, before and after therapy with compliance rate of >95.2%). Moreover, we found an association between hs-CRP and BMI, triglyceride, white blood cell count, and lymphocytes. Interestingly we observed a significant reduction in neutrophil count and CRP level after high dose vitamin D supplementation. Our findings showed that the high dose supplementation of vitamin D affects measures of systemic inflammation: reductions in High Sensitivity C-Reactive Protein level and Neutrophil-to-lymphocyte ratio (NLR) distribution. J. Cell. Biochem. 118: 4317-4322, 2017. © 2017 Wiley Periodicals, Inc.

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.

Inverse Association between Vitamin D Status and Diabetes in a Clinic Based Sample of Hispanic Adults in Puerto Rico

BACKGROUND

Vitamin D deficiency is a public health problem around the world. Diabetes has been associated with vitamin D deficiency. We aimed to examine the association between the vitamin D status and diabetes in a clinic based sample of Hispanic adults in Puerto Rico.

METHODS

Demographics and laboratory test results for serum 25(OH)D, Fasting Blood Glucose (FBG), and Haemoglobin A1C (HbAlc) were extracted from medical records. Vitamin D status was classified as deficient (<12 ng/ml); inadequate (12-20 ng/ml); insufficient (21-29 ng/ml) and optimal (≥30 ng/ml) using serum 25(OH)D levels.

RESULTS

A total of 716 records were included in the analyses. Most were females (63.3%), with mean age of 54.1±14.9 y, mean BMI 30.1±6.3 kg/m2 and mean serum 25(OH)D levels of 24.3±8.6 ng/ml. Most were classified as diabetics (41.1%). Those with diabetes had lower 25(OH)D levels compared to pre-diabetic and normal glucose status (p<0.05). Serum 25(OH) D levels were inversely correlated to FBG and HbA1c in the total sample and in men (p<0.05). After adjusting for age, gender, BMI and seasonality, there was a greater risk of diabetes, but not prediabetes, in those with serum 25(OH)D levels <30 ng/ml. This risk increased from 1.8 times in those with vitamin D insufficiency to 4.2 times in those with vitamin D deficiency (<12 ng/ml).

CONCLUSION

Diabetes risk significantly increased as serum 25(OH)D levels decreased in this group of Hispanic adults, underscoring the importance of routinely screening high risk individuals for vitamin D deficiency and offer supplementation to normalize serum levels.

Association of vitamin D levels with type 2 diabetes in older working adults

OBJECTIVES

Increasing evidence suggests that vitamin D plays a role in the development of chronic diseases including type 2 diabetes (DM). Aim of the study was to explore the association of vitamin D levels with prevalent DM in a sample of predominantly healthy working adults older than 45 years.

METHODS

This cross-sectional study (2009-2011) involved 1821 employees of a German engineering company (83.1% male, mean age 51.9 ±5.6 years). Sociodemographics and medical history were assessed by self-report. Clinical characteristics were obtained including blood samples to determine vitamin D levels and diabetes status by fasting plasma glucose (FPG) and glycosylated hemoglobin (HbA1c). Vitamin D was grouped into one of four categories (<10 ng/ml, 10-19.9 ng/ml, 20-29.9 ng/ml, ≥30 ng/ml). Bivariate associations between vitamin D categories and a composite indicator for DM (FPG ≥126 mg/dl or HbA1c ≥6.5% or self-reported diagnosis) were calculated; multivariable models tested this association further, controlling for potential confounders.

RESULTS

Severe vitamin D deficiency (<10 ng/ml) was associated with increasing FPG (β 3.13; 95% CI: 0.78, 5.47; p≤0.01) and HbA1c (β 0.15; 95% CI: 0.08, 0.23; p≤0.001) values in adjusted linear regression models. In multivariable models, severe vitamin D deficiency was associated with DM (OR 2.55; 95%CI 1.16, 5.62; p≤0.05) after controlling for potential confounders.

CONCLUSIONS

Vitamin D deficiency is associated with prevalent DM in working older adults. The findings highlight that the workplace may be a unique location for conducting large-scale health screening to identify those at risk of DM using vitamin D.

Correlations between serum levels of 25-hydroxyvitamin D and carotid atherosclerosis in patients with type 2 diabetes in Shanghai

OBJECTIVE

To explore the potential association between the serum levels of 25-hydroxyvitamin D [25(OH)D] and carotid atherosclerosis in patients with type 2 diabetes.

MATERIAL AND METHODS

Three hundred and fifty patients with type 2 diabetes were enrolled in this study in Shanghai, China. B-mode ultrasound was used to detect carotid plaques as indicators of atherosclerosis and measure carotid artery intima-media wall thickness (C-IMT) at two sites of carotid artery. Subjects were divided into group A (patients with carotid plaques) and group B (patients without carotid plaques) and be assessed clinically. Serum levels of 25(OH)D and other clinical parameters were measured. Multivariate logistic regression was performed to find predictors of carotid atherosclerosis in the entire group.

RESULTS

The levels of serum 25(OH)D were lower in group A than in group B[19.60 (13.30-25.73) vs 23.19 (18.10-30.06)ng/ml, P<0.001]. The C-IMT levels [(1.00±0.17 vs 0.88±0.20)mm, Ptrend<0.001] and proportion of people with carotid plaques(44/88 vs 20/87, Ptrend<0.001) in the lowest quartile of 25(OH)D were higher than in the highest quartile. Vitamin D concentrations were inversely associated with HbA1c in women(r=-0.194, P=0.006), and C-IMT in men(r=-0.409, P<0.001). Logistic regression analysis showed age, male sex, current smoke, history of hypertension, SBP, LDL-C and lg[25(OH)D] (OR: 0.924, 95%CI: 0.893-0.955, P<0.001) were independently associated with the presence of carotid plaques in T2DM.

CONCLUSIONS

Serum vitamin D level is significantly and independently associated with carotid atherosclerosis in patients with T2DM in Shanghai, China.

Effects of vitamin D supplementation on glucose metabolism, lipid concentrations, inflammation, and oxidative stress in gestational diabetes: a double-blind randomized controlled clinical trial

BACKGROUND

To our knowledge, there is no study that has examined the effects of vitamin D supplementation on metabolic status in gestational diabetes mellitus (GDM).

OBJECTIVE

This study was designed to assess the effects of vitamin D supplementation on metabolic profiles, high-sensitivity C-reactive protein, and biomarkers of oxidative stress in pregnant women with GDM.

DESIGN

This randomized, double-blind, placebo-controlled clinical trial was conducted in 54 women with GDM. Subjects were randomly assigned to receive either vitamin D supplements or placebo. Individuals in the vitamin D group (n = 27) received capsules containing 50,000 IU vitamin D₃ 2 times during the study (at baseline and at day 21 of the intervention) and those in the placebo group (n = 27) received 2 placebos at the same times. Fasting blood samples were collected at baseline and after 6 wk of the intervention to quantify relevant variables.

RESULTS

Cholecalciferol supplementation resulted in increased serum 25-hydroxyvitamin D concentrations compared with placebo (+18.5 ± 20.4 compared with +0.5 ± 6.1 ng/mL; P < 0.001). Furthermore, intake of vitamin D supplements led to a significant decrease in concentrations of fasting plasma glucose (-17.1 ± 14.8 compared with -0.9 ± 16.6 mg/dL; P < 0.001) and serum insulin (-3.08 ± 6.62 compared with +1.34 ± 6.51 μIU/mL; P = 0.01) and homeostasis model of assessment-insulin resistance (-1.28 ± 1.41 compared with +0.34 ± 1.79; P < 0.001) and a significant increase in the Quantitative Insulin Sensitivity Check Index (+0.03 ± 0.03 compared with -0.001 ± 0.02; P = 0.003) compared with placebo. A significant reduction in concentrations of total (-11.0 ± 23.5 compared with +9.5 ± 36.5 mg/dL; P = 0.01) and low-density lipoprotein (LDL) (-10.8 ± 22.4 compared with +10.4 ± 28.0 mg/dL; P = 0.003) cholesterol was also seen after vitamin D supplementation.

CONCLUSIONS

Vitamin D supplementation in pregnant women with GDM had beneficial effects on glycemia and total and LDL-cholesterol concentrations but did not affect inflammation and oxidative stress. This trial was registered at www.irct.ir as IRCT201305115623N7.

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.

Vitamin D supplementation affects serum high-sensitivity C-reactive protein, insulin resistance, and biomarkers of oxidative stress in pregnant women

Unfavorable metabolic profiles and oxidative stress in pregnancy are associated with several complications. This study was conducted to determine the effects of vitamin D supplementation on serum concentrations of high-sensitivity C-reactive protein (hs-CRP), metabolic profiles, and biomarkers of oxidative stress in healthy pregnant women. This randomized, double-blind, placebo-controlled clinical trial was conducted in 48 pregnant women aged 18-40 y old at 25 wk of gestation. Participants were randomly assigned to receive either 400 IU/d cholecalciferol supplements (n = 24) or placebo (n = 24) for 9 wk. Fasting blood samples were taken at study baseline and after 9 wk of intervention to quantify serum concentrations of hs-CRP, lipid concentrations, insulin, and biomarkers of oxidative stress. After 9 wk of intervention, the increases in serum 25-hydroxyvitamin D and calcium concentrations were greater in the vitamin D group (+3.7 μg/L and +0.20 mg/dL, respectively) than in the placebo group (-1.2 μg/L and -0.12 mg/dL, respectively; P < 0.001 for both). Vitamin D supplementation resulted in a significant decrease in serum hs-CRP (vitamin D vs. placebo groups: -1.41 vs. +1.50 μg/mL; P-interaction = 0.01) and insulin concentrations (vitamin D vs. placebo groups: -1.0 vs. +2.6 μIU/mL; P-interaction = 0.04) and a significant increase in the Quantitative Insulin Sensitivity Check Index score (vitamin D vs. placebo groups: +0.02 vs. -0.02; P-interaction = 0.006), plasma total antioxidant capacity (vitamin D vs. placebo groups: +152 vs. -20 mmol/L; P-interaction = 0.002), and total glutathione concentrations (vitamin D vs. placebo groups: +205 vs. -32 μmol/L; P-interaction = 0.02) compared with placebo. Intake of vitamin D supplements led to a significant decrease in fasting plasma glucose (vitamin D vs. placebo groups: -0.65 vs. -0.12 mmol/L; P-interaction = 0.01), systolic blood pressure (vitamin D vs. placebo groups: -0.2 vs. +5.5 mm Hg; P-interaction = 0.01), and diastolic blood pressure (vitamin D vs. placebo groups: -0.4 vs. +3.1 mm Hg; P-interaction = 0.01) compared with placebo. In conclusion, vitamin D supplementation for 9 wk among pregnant women has beneficial effects on metabolic status.

Role of vitamin D in the development of insulin resistance and type 2 diabetes

Vitamin D deficiency is mainly a consequence of insufficient sunlight induced vitamin D production in the skin and has been associated with various chronic diseases including type 2 diabetes. Experimental data have shown that vitamin D is important for glucose induced insulin secretion, improves insulin resistance, and exerts anti-inflammatory actions. Epidemiological studies have largely documented that a poor vitamin D status is associated with higher risk of insulin resistance and type 2 diabetes. The majority of randomized controlled trials (RCTs) in healthy or prediabetic individuals have, however, failed to demonstrate relevant vitamin D effects on insulin resistance or diabetes incidence. In patients with type 2 diabetes, a few RCTs reported some moderate effects of vitamin D on glycemic control and insulin resistance. While these findings warrant further in-depth studies, the current evidence is insufficient to recommend vitamin D supplementation for the prevention or treatment of type 2 diabetes.