Vitamin D status is inversely associated with markers of risk for type 2 diabetes: A population based study in Victoria, Australia

Additive Interaction Between Insulin Resistance, Chronic Low-Grade Inflammation and Vitamin D Deficiency on the Risk of Type 2 Diabetes Mellitus: A Cohort Study

OBJECTIVES

The aim of this study was to explore, on an additive scale, the combined effect of the association between insulin resistance (IR), chronic low-grade inflammation (CLGI) and vitamin D deficiency (VDD) on the risk of type 2 Diabetes Mellitus (T2DM).

METHODS

This is a cohort study, including 1484 non-diabetic subjects, followed for a period of four years. 25 hydroxy-vitamin D (25OHD), hypersensitive C-reactive protein (HsCRP) and triglyceride-glucose index were assessed. Based on VDD and CLGI, the population was subdivided into 4 exposure groups. Analysis was performed both in the case of IR and without IR. Cox proportional regression and additive interaction were applied to explore cumulative effects of exposure.

RESULTS

At follow-up, 162 newly diagnosed cases of T2DM were identified. TYG index (RR = 4.0[2.8-5.6]), HsCRP (RR = 1.6 [1.4-1.7]) and 25OHD (RR = 0.96 [0.39-0.98]) were all significantly associated with the risk of T2DM (p < 0.01). The highest excess risk was recorded in patients cumulating simultaneously IR, CLGI and VDD (RR= 8.4[3.6-19.8], p < 0.0001). The additive interaction was significant, the excess risk linked to the interaction RERI = 10.5[1.43-19.7], the proportion attributable to the combined effect: AP = 0.61[0.37-0.85], and the interaction was synergistic: synergy index: 2.8[1.42-5.69].

CONCLUSION

Baseline levels of TYG index, 25OHD and HsCRP are strongly predictive of future T2DM, and their joint effects are additive and synergistic. Interventional studies are therefore warranted in order to evaluate whether vitamin D supplementation, combined with appropriate anti-inflammatory therapies, is effective as a preventive strategy to reduce the risk of T2DM.

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

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

Vitamin D deficiency and hyperglycemia in male rotating shift workers: A disturbed circadian rhythms influence

BACKGROUND

Shift work is related to several negative impacts on the health of workers. This study aimed to evaluate the association between vitamin D deficiency (VDD) and hyperglycemia in shift workers.

METHODOLOGY

This cross-sectional study included male rotating shift workers in an iron ore extraction company. Participants were classified as VDD when 25(OH)D < 20 ng/mL for a healthy population and 25(OH)D < 30 ng/mL for groups at risk for VDD. Hyperglycemia was classified when fasting glucose ≥100 mg/dL or HbA1c ≥ 5.7%. Data were compared using chi-square analysis with Cramer's V as effect size, and Bonferroni correction. Multivariate logistic regression, from a model of determination, was performed to investigate whether VDD was associated with hyperglycemia.

RESULTS

The study evaluated 1411 workers, most workers were aged 30-39 years (53.2%), and 77.5% self-declared as black, brown, with up to complete high school (71.4%) and working alternate shifts for more than 5 years (76.1%). Regarding glucose and vitamin D, 32.0% and 29.1% of the workers had hyperglycemia and VDD, respectively. In multivariate analysis, controlled for confounding factors, workers with VDD had a 119% increased chance of hyperglycemia (OR: 2.19; IC95%: 1.56-3.08). Furthermore, vitamin D levels in distribution quintiles showed a dose-response gradient in relation to hyperglycemia, where increased vitamin D values were associated with a reduction in the occurrence of hyperglycemia.

CONCLUSION

Rotating shift workers with vitamin D deficiency are more likely to have hyperglycemia.

Fasting plasma glucose and serum 25-hydroxy vitamin D levels in individuals with Middle Eastern and Swedish descent

Purpose

To determine fasting plasma glucose and serum 25-hydroxyvitamin D (s-25(OH)D) levels and associations between abnormal fasting plasma glucose levels and inadequate s-25(OH)D levels in individuals of Middle Eastern and Swedish descent.

Methods

Observational study with individuals without a diabetes diagnosis, 54.5% of Swedish descent and 45.5% of Middle Eastern descent. In total, 830 participants from two primary healthcare centres in Flemingsberg and Jakobsberg, which are southern and northern suburbs, respectively, of Stockholm, Sweden were included in the study.

Results

Prevalence of inadequate s-25(OH)D levels (at or below 50 nmol/L) was 67.2% among those of Middle Eastern descent and 20.5% among those of Swedish descent (P < 0.001). S-25(OH)D levels correlated weakly positively with fasting plasma glucose levels (ρ = 0.20, P = 0.002) in individuals of Middle Eastern descent. Being of Middle Eastern descent (OR 6.7, 95% CI 4.3-10.4) and having abnormal fasting plasma glucose (OR 1.8, 95% CI 1.2-2.9) were independent predictors of having inadequate s-25(OH)D levels.

Conclusions

Healthcare in Sweden should consider testing fasting plasma glucose and s-25(OH)D levels, particularly in individuals of Middle Eastern descent. The unclear relationship between vitamin D and glucose levels warrants investigation.

Supplementary Information

The online version contains supplementary material available at 10.1007/s40200-023-01226-0.

Fish consumption in multiple health outcomes: an umbrella review of meta-analyses of observational and clinical studies

Background

Omega-3 polyunsaturated fatty acids are known to be associated with numbers of health benefits, and which can be uptake from fish. The aim of this study was to evaluate the current evidence of associations between consumption of fish and diverse health outcomes. Here, we performed an umbrella review to summarize the breadth, strength, and validity of the evidence derived from meta-analyses and systematic reviews of fish consumption on all health outcomes.

Methods

The methodological quality of the included meta-analyses and the quality of the evidence were assessed by the Assessment of Multiple Systematic Reviews (AMSTAR) and the grading of recommendations, assessment, development, and evaluation (GRADE) tools, respectively. The umbrella review identified 91 meta-analyses with 66 unique health outcomes, of which 32 outcomes were beneficial, 34 showed nonsignificant associations and only one was harmful (myeloid leukemia).

Results

A total of 17 beneficial associations [all-cause mortality, prostate cancer mortality, cardiovascular disease (CVD) mortality, esophageal squamous cell carcinoma (ESCC), glioma, non-Hodgkin lymphoma (NHL), oral cancer, acute coronary syndrome (ACS), cerebrovascular disease, metabolic syndrome, age-related macular degeneration (AMD), inflammatory bowel disease (IBD), Crohn's disease (CD), triglycerides, vitamin D, high-density lipoprotein (HDL)-cholesterol, and multiple sclerosis (MS)], and eight nonsignificant associations [colorectal cancer (CRC) mortality, esophageal adenocarcinoma (EAC), prostate cancer, renal cancer, ovarian cancer, hypertension, ulcerative colitis (UC), and rheumatoid arthritis (RA)] were evaluated as moderate/high quality of evidence. According to dose-response analyses, consumption of fish, especially fatty types, seems generally safe at one-two servings per week and could exert protective effects.

Conclusions

Fish consumption is often associated with a variety of health outcomes, both beneficial and harmless, but only about 34% of the associations were graded as based on a moderate/high quality of evidence, and additional multicenter high quality randomized controlled trials (RCTs) with a large sample size are needed to verify these findings in the future.

Vitamin D Deficiency During the First Trimester of Pregnancy and the Risk of Developing Gestational Diabetes Mellitus

OBJECTIVE

To investigate the relationships among various factors that affect serum vitamin D levels and vitamin D in the first trimester and the risk of developing gestational diabetes mellitus (GDM).

DESIGN

A prospective cohort design.

SETTING

The family health center of Ankara, Turkey.

PARTICIPANTS

Out of 889 pregnant women who participated in the study in the first trimester (6-13 weeks gestation), 814 participated in GDM screening in the second trimester (24-28 weeks gestation).

METHODS

We determined serum vitamin D levels, demographic data, various biochemical and anthropometric parameters, and factors that affect vitamin D synthesis of participants in the first trimester and used logistic regression analysis to analyze the effects of the associations among vitamin D deficiency and the other variables on the occurrence of GDM.

RESULTS

Vitamin D deficiency in the first trimester was present in 425 (82.5%) participants. In the second trimester, 198 participants (24.3%) were diagnosed with GDM through oral glucose tolerance test screening. We detected GDM in the second trimester in 5.7% of participants who had vitamin D deficiency in the first trimester. Even after adjustment for vitamin D intake, clothing style, and duration of exposure to the sun, the risk of GDM was significantly greater in participants who were vitamin D deficient than those who were not deficient. The risk of GDM among women with vitamin D deficiency was sustained or increased significantly after we adjusted for age, parity, prepregnancy body mass index, history of diabetes, triglyceride levels, vitamin D intake, clothing style, and length of sun exposure, OR = 10.60, p < .001, 95% confidence interval [2.82, 39.76].

CONCLUSIONS

Our results suggest that vitamin D deficiency in the first trimester may significantly increase the risk of developing GDM.

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.

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.

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

Background

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

Objective

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

Methods

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

Results

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

Conclusion

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

Directional Relationship Between Vitamin D Status and Prediabetes: A New Approach from Artificial Neural Network in a Cohort of Workers with Overweight-Obesity

Objective: Despite the increasing literature on the association of diabetes with inflammation, cardiovascular risk, and vitamin D (25(OH)D) concentrations, strong evidence on the direction of causality among these factors is still lacking. This gap could be addressed by means of artificial neural networks (ANN) analysis.Methods: Retrospective observational study was carried out by means of an innovative data mining analysis-known as auto-contractive map (AutoCM)-and semantic mapping followed by Activation and Competition System on data of workers referring to an occupational-health outpatient clinic. Parameters analyzed included weight, height, waist circumference, body mass index (BMI), percentage of fat mass, glucose, insulin, glycated hemoglobin (HbA1c), creatinine, total cholesterol, low- and high-density lipoprotein cholesterol, triglycerides, uric acid, fibrinogen, homocysteine, C-reactive protein (CRP), diastolic and systolic blood pressure, and 25(OH)D.Results: The study included 309 workers. Of these, 23.6% were overweight, 40.5% were classified into the first class of obesity, 23.3% were in the second class, and 12.6% were in the third class (BMI > 40 kg/m ). All mean biochemical values were in normal range, except for total cholesterol, low- and high-density lipoprotein cholesterol, CRP, and 25(OH)D. HbA1c was between 39 and 46 mmol/mol in 51.78%. 25(OH)D levels were sufficient in only 12.6%. Highest inverse correlation for hyperglycemia onset was with BMI and waist circumference, suggesting a protective role of 25(OH)D against their increase. AutoCM processing and the semantic map evidenced direct association of 25(OH)D with high link strength (0.99) to low CRP levels and low high-density lipoprotein cholesterol levels. Low 25(OH)D led to changes in glucose, which affected metabolic syndrome biomarkers, first of which was homeostatic model assessment index and blood glucose, but not 25(OH)D.Conclusions: The use of ANN suggests a key role of 25(OH)D respect to all considered metabolic parameters in the development of diabetes and evidences a causation between low 25(OH)D and high glucose concentrations.

The association between types of seafood intake and the risk of type 2 diabetes: a systematic review and meta-analysis of prospective cohort studies

Background: Seafood is the main source of long-chain n-3 polyunsaturated fatty acids (n-3PUFAs) with beneficial health effects; however, findings on the association between the consumption of different types of seafood and type 2 diabetes mellitus (T2DM) are conflicting. Our objective was to perform a systematic review and meta-analysis examining the relationship between different types of fish/seafood and the risk of T2DM in adult populations. Methods: A systematic search of PubMed/Medline, Scopus, and Web of Science (ISI) databases was performed for cohort studies, published in English, before 1 September 2017. Multivariate adjusted relative risk (RR) estimates with 95% confidence intervals (CIs) for each category of seafood were pooled to examine the association. Results: Comparing the highest vs. lowest fatty fish intake categories indicated that there was a significant inverse association between the consumption of fatty fish and onset of T2DM (RR:0.89; 95 % CI: 0.82, 0.98; I2: 0%, P=0.54). However, after performing sensitivity analysis, we found that eliminating one study resulted in a non-significant association (RR: 0.93; 95 % CI:0.80, 1.09). There were no significant associations between lean fish (RR: 1.03; 95% CI: 0.87,1.22, I2: 51.0%, P=0.08), seafood other than fish (RR: 0.95; 95% CI: 0.83, 1.10, I2: 71.2%,P=0.002), fish products (RR: 0.96; 95% CI: 0.82, 1.13, I2:0%, P=0.62), and fried fish (RR: 1.02;95% CI: 0.83, 1.26, I2:71.2%, P=0.06) and T2DM risk. Conclusion: The risk of T2DM was not associated with the intake of lean fish, seafood other than fish, and fish products. However, due to the low robustness of findings regarding protective roles of oily fish, more longitudinal studies are needed to clarify this association.

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

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

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

AIMS

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

Higher serum levels of vitamin D are associated with lower blood glucose levels

OBJECTIVE

Vitamin D plays an important role in bone metabolism. There is now evidence that a higher serum level of 25-hydroxyvitamin D (25[OH]D) is associated with a lower risk of developing type 2 diabetes mellitus, because it provides better glycemic control, possibly by promoting greater insulin sensitivity, and also by improving pancreatic beta cell function. The objective of the present study was to evaluate the possible association between 25(OH)D sufficiency and glycemia.

METHODS

This was a cross-sectional study involving 680 women, 35 to 74 years of age, selected through systematic sampling. From each participant, fasting blood samples were collected for the determination of 25(OH)D and glucose levels.

RESULTS

The mean fasting blood glucose level was 105 mg/dL (range 26-401 mg/dL). Fasting serum levels of 25(OH)D were <30 ng/mL in 65.4% of the participants and <20 ng/mL in 25.6%. A serum 25(OH)D level <30 ng/mL was positively associated with a blood glucose level ≥100 mg/dL (odds ratio [OR] 1.29, 95% confidence interval [CI] 1.05-1.57), as was a serum 25(OH)D level <20 ng/mL (OR 1.25, 95% CI 1.04-1.50).

CONCLUSIONS

Lower serum 25(OH)D concentrations appear to be associated with a high blood glucose levels.

New Insights on Low Vitamin D Plasma Concentration as a Potential Cardiovascular Risk Factor

The role of Vitamin D hormone in human health and disease is still debated. Recently, growing attention has been paid to its putative role in cardiovascular system homeostasis with several studies that suggested a correlation between low vitamin D levels and increased cardiovascular risk. Several mechanisms are involved in the development of cardiovascular diseases: systemic inflammation, endothelial dysfunction, arterial hypertension and insulin resistance. In the present paper, we have revised the current literature supporting a role for vitamin D in the development of these pathogenetic processes. Finally, we have evaluated the current evidence linking vitamin D to atherosclerosis and its natural consequence, cardiovascular diseases.

Sex-specific correlation of IGFBP-2 and IGFBP-3 with vitamin D status in adults with obesity: a cross-sectional serum proteomics study

Objective

Subjects with low vitamin D levels are at risk of cardiometabolic disease. The aim of this study was to identify novel serological markers linking vitamin D status with cardiometabolic profile in non-diabetic adults with obesity.

Methods

For the discovery phase, we used quantitative serum proteomics in sex-matched, age-matched and BMI-matched subjects with obesity [BMI: 25–35 kg/m²] and low [25(OH)D < 50 nmol/L] vs. high vitamin D status [25(OH)D > 50 nmol/L] (n = 16). For the validation phase, we performed ELISA in a larger cohort with similar characteristics (n = 179).

Results

We identified 423 and 549 differentially expressed proteins in the high vs. low vitamin D groups of the male and female cohorts, respectively. The small molecule biochemistry protein networks and the glycolysis|gluconeogenesis pathway were significantly enriched in the DEPs of both sexes. As surrogate markers to these processes, the insulin-like growth factor binding protein -2  (IGFBP-2) was upregulated in males, whereas   IGFBP-3 was upregulated in females from the high Vitamin D status. This sex-specific trend  was confirmed using Luminex ELISA to an independent but clinically analogous cohort of males (n = 84, p = 0.002) and females (n = 95, p = 0.03).

Conclusions

The high Vitamin D status correlated with the serological upregulation of IGFBP-2 in males and IGFBP-3 in females with obesity and may constitute surrogate markers of risk reduction of cardiometabolic disease.

Associations of vitamin D status with markers of metabolic health: A community-based study in Shanghai, China

AIMS

This study investigated the associations of vitamin D status (i.e., serum 25(OH)D concentration) with markers of metabolic health and metabolic syndrome (MS), as well as possible gender differences in these associations, with metabolic syndrome (MS) for a sample from Shanghai, China.

METHODS

Demographic and anthropometric data, as well as 25-hydroxyvitamin D (serum 25(OH)D), blood glucose, and lipid concentrations were obtained for 508 urban residents aged 19-70 years. After grouping into tertiles according to their serum 25(OH)D concentrations, linear and logistic regressions were used to evaluate associations between serum 25(OH)D concentration and risk factors for MS across tertiles.

RESULTS

A 1 ng/mL increase in 25(OH)D was associated with a significant decrease in total cholesterol by 0.25 mmol/L [95% CI: (-0.44, -0.05); P = 0.014] for the third tertile, with reference to the first tertile. Also, 1 ng/mL increase in 25(OH)D was associated with a significant decrease in LDL by 0.18 mmol/L [95% CI: (-0.35, -0.02); P = 0.026] for the third tertile. In addition, participants in the third tertile had a 54% reduction in the OR for MS [95% CI: (-1.10,- 0.02), P = 0.041]. Lastly, while there was no gender difference in vitamin D deficiency status, the non-MS women had significantly higher 25(OH)D level than those with MS (30.1 ± 5.8 vs. 28.5 ± 5.9 ng/mL, P = 0.035), while no such difference was observed for men.

CONCLUSIONS

Higher serum 25(OH)D concentration was associated with a better metabolic profile and thus a lower risk for developing MS in urban Shanghai residents of China.

Efficacy of Vitamin D interventional strategies in saudi children and adults

Despite the amount of sunshine in Saudi Arabia, vitamin D (25(OH)D) deficiency is highly prevalent among Saudis. Several strategies are known to improve 25(OH)D status. The aim of this study was to evaluate the efficacy of different interventional strategies in improving 25(OH)D status in Saudi children and adults. This interventional study was undertaken among 593 out of 1152 Saudi subjects [530 students (aged 13-17 years) and 63 teachers (aged 26-46 years)] over a 6-month period from different secondary schools in Riyadh, Saudi Arabia. 25(OH)D status was taken at baseline and after 6 months post interventions. Subjects were divided into 3 groups and requested to implement different vitamin D correction schemes: sun-exposure, vitamin D-fortified milk consumption, and oral vitamin D supplementation (1000IU/day). Follow-up results revealed that all correction strategies used could decrease the deficiency of serum 25(OH)D with different potencies, with the highest positive percentage change observed in oral supplementation in both adults and children (11% men, 17% women, 16% boys and 8% girls). The oral vitamin D supplementation strategy also showed significant positive associations between delta (Δ) changes and HDL-cholesterol in both adults and children. In conclusion, oral vitamin D supplementation was the most effective strategy in improving vitamin D status in Saudi adults and children than sunlight exposure or consumption of vitamin D-fortified dairy products.

Effect of vitamin D supplementation on fasting plasma glucose, insulin resistance and prevention of type 2 diabetes mellitus in non-diabetics: A systematic review and meta-analysis

Increasing epidemiological studies suggest that there is an association between vitamin D deficiency and risk of type 2 diabetes mellitus (T2DM). Therefore, randomized clinical trials (RCTs) have been performed to observe the effect of vitamin D supplementation on preventing T2DM, decreasing fasting plasma glucose (FPG) and improving insulin resistance to confirm the association between vitamin D and T2DM. However, the results of RCTs on controlling FPG level, improving insulin resistance and preventing T2DM in non-diabetics are inconsistent. In the present study, a systematic meta-analysis considering individual variation and intervention strategy was conducted to establish an objective and definitive conclusion. The results suggested that vitamin D supplementation had no significant effect on controlling FPG level, improving insulin resistance or preventing T2DM in non-diabetics in a pooled meta-analysis of 23 articles (containing 28 RCTs). However, stratified analysis indicated that supplementation of vitamin D had differential effects on FPG control, insulin sensitivity improvement and T2DM prevention in individuals with different baseline states: FPG was decreased for those with BMI <25 (P=0.048) or 20≤ 25(OH)D <30 ng/ml (P=0.002); insulin resistance was improved for those with 25(OH)D ≥30 ng/ml (P=0.021); and risk of T2DM was lower for pre-diabetic individuals (P=0.047) or for those with 25≤ BMI <30 (P=0.032). Additionally, the effect on T2DM prevention was improved when the supplement dose was >2,000 IU/day (P=0.047) and with intervention without calcium (P=0.047). Thus, further trials should focus on individual baselines and the supplementation strategy of vitamin D in the prevention of T2DM.

Association of vitamin D status with metabolic syndrome and its components: A cross-sectional study in a population of high educated Iranian adults

AIM

We aimed to assess the association of vitamin D status with metabolic syndrome and its components among high educated Iranian adults.

METHOD

In this cross-sectional study, 352 faculty members with age of 35 years or more, belong to Tarbiat Modares University, Tehran, Islamic Republic of Iran, were recruited during 2016 and 2017. Fasting blood samples were obtained to quantify serum 25(OH)D concentrations, glycemic indicators and lipid profile. Metabolic syndrome was defined based on the guidelines of the National Cholesterol Education Program Adult Treatment Panel III (ATP III). Multivariate logistic regression adjusted for potential confounders was used to evaluate the association between vitamin D status and metabolic syndrome.

RESULT

Metabolic syndrome and vitamin D insufficiency were prevalent among 26% and 60.2% of subjects, respectively. There was no statistically significant difference in the prevalence of metabolic syndrome across quartiles of 25(OH)D levels either before or after adjusting for potential confounders (OR: 0.94, 95% CI: 0.43-1.95). In terms of metabolic syndrome components, subjects in the highest quartile of vitamin D levels had 59% decreased risk of abdominal obesity compared with those in the lowest quartile (OR: 0.41, 95% CI: 0.17-0.99), after adjusting for potential confounders. Such inverse relationship was also seen for elevated blood pressure (OR: 0.37, 95% CI: 0.14-0.99), and abnormal glucose homeostasis (OR: 0.40, 95% CI: 0.19-0.85).

CONCLUSION

Serum levels of 25(OH)D was inversely associated with the risk of abdominal obesity, hypertension, and abnormal glucose homeostasis. However, no significant relationship was seen for metabolic syndrome.

Methylation in 3' near region of GC gene and its association with the level of vitamin D binding protein and type 2 diabetes mellitus

As the major vitamin D binding protein (DBP), the group-specific component (GC) plays an important role in the bioactivity of vitamin D. Abnormal expression of GC gene may be associated with vitamin D related disease, type 2 diabetes mellitus (T2DM). DNA methylation is an important regulator of gene expression. It has been reported that methylation in 3' untranslated region played a role in regulation of protein expression via interaction with miRNA. This study hypothesized that DNA methylation of 3' near region of GC gene (3'GC) might be associated with T2DM. The methylation status of the 3'GC was assessed with high resolution melt method. Logistic regression was applied to assess the risk of T2DM at different levels of 3'GC methylation. The results showed that methylation level of the 3'GC was higher in T2DM patients than in non-T2DM individuals (P=.038). There was a significant association between 3'GC methylation level and T2DM (adjusted OR 1.282; 95% CI 1.062-1.548; P=.01). The association was independent upon serum glucose and insulin (adjusted OR 1.561; 95% CI 1.083-2.249; P=.017). Furthermore, there was a positive correlation between methylation level and the level of DBP in T2DM patients (r=0.126, P=.036). The association was also significant after adjusting the potential impact of rs705117 (P=.044). Besides, a positive correlation between methylation level and the level of fasting serum insulin was observed in non-T2DM (r=0.101, P<.001). These results suggest that methylation status of the 3'GC is most likely associated with DBP expression, insulin secretion, and T2DM.

Transmission disequilibrium of rs4809957 in type 2 diabetes mellitus families and its association with vitamin D deficiency: A family-based case-control study

AIMS

Association between T2DM and vitamin D was found in many epidemiologic reports. And 24-hydroxylase encoded by CYP24A1 is the very enzyme that degrades the active vitamin D metabolite. We aimed to investigate the association between rs4809957 in CYP24A1 and T2DM, as well as vitamin D level.

METHODS

A total of 419 pedigrees containing 1556 participants were included. T2DM diagnosis, 25(OH)D measurement and genotyping of rs4809957 were conducted for all the individual. Then association between rs4809957 and T2DM, as well as 25(OH)D level, was investigated by family-based association test (FBAT) and 1:1 matched case-control study.

RESULTS

The FBAT results revealed that there was transmission disequilibrium for allele G in T2DM families by both additive model (Z = 2.183, P = 0.029049) and recessive model (Z = 2.236, P = 0.025347). Allele G was also associated with 25(OH)D level in both additive model (Z = 2.549, P = 0.010811) and dominant model (Z = 2.012, P = 0.044187). On the other hand, results of case-control study suggested that vitamin D deficiency was a risk factor for T2DM (OR 1.987; 95%CI 1.331-2.964; P = 0.001). Further stratified analysis revealed that vitamin D deficiency increased T2DM risk in women (OR 2.347; 95%CI 1.373-4.012; P = 0.002), instead of men (OR 1.600; 95%CI 0.874-2.931; P = 0.127). In addition, T2DM patients with GG and AG genotypes were more susceptible to vitamin D deficiency than the control (P = 0.006 and P = 0.038, respectively).

CONCLUSION

There was transmission disequilibrium for allele G of rs4809957 in T2DM families, which was linked to vitamin D deficiency.

Effects of Glucan and Vitamin D Supplementation on Obesity and Lipid Metabolism in Diabetic Retinopathy

Background:

Diabetes mellitus is a chronic disease manifested by an increase of blood glucose.

Objective:

To evaluate the effects of glucan and vitamin D supplementation in patients with diabetic retinopathy.

Method:

We evaluated the effects of 3-month supplementation with glucan and vitamin D in 54 patients with diabetic retinopathy. We measured levels of vitamin D, cholesterol, HDL cholesterol, and triglycerides.

Results:

The supplementation strongly decreased the cholesterol levels and improved the levels of HDL cholesterol. In addition, vitamin D levels were strongly improved, but still not at optimal values.

Conclusion:

From our data, we concluded that glucan and vitamin D supplementation strongly influence lipid metabolism and have positive effects on human health.

Maternal transmission disequilibrium of rs2248359 in type 2 diabetes mellitus families and its association with vitamin D level in offspring

Association between T2DM and vitamin D deficiency has been reported in many epidemiologic studies. 24-hydroxylase encoded by CYP24A1 is the enzyme that degrades the active vitamin D metabolite. Variation in CYP24A1 may be associated with T2DM. This study investigates the association between rs2248359 in CYP24A1 and T2DM by a family-based association test (FBAT) and in a case-control study. The FBAT results revealed that there was transmission disequilibrium for allele T in both additive model (Z = 2.041, P = 0.041227) and dominant model (Z = 2.722, P = 0.006496). Results of the case-control study suggested that rs2248359 may be a risk factor for female T2DM (P = 0.036) but not for male T2DM (P = 0.816). Furthermore, excessive transmission of allele T in T2DM offspring was observed compared with the non-T2DM offspring (OR 1.392; 95%CI 1.024–1.894; P = 0.035). In addition, combination of maternal CT and paternal CC genotypes had significant synergistic effect on obtaining CT genotype for offspring with T2DM (OR 6.245; 95%CI 1.868–20.883; P = 0.004). Besides, lower level of 25(OH)D in T2DM offspring with genotype CT was observed as compared with the non-T2DM offspring (P = 0.013). These data suggest that maternal transmission disequilibrium of allele T may be a risk factor for T2DM and vitamin D deficiency in T2DM offspring.

Is Hypovitaminosis D Related to Incidence of Type 2 Diabetes and High Fasting Glucose Level in Healthy Subjects: A Systematic Review and Meta-Analysis of Observational Studies

There is evidence that vitamin D status is associated with type 2 diabetes. Many observational studies have been performed investigating the relationship of vitamin D status and circulating biomarkers of glycemic regulation. To find out whether this association holds, we conducted a systematic review and meta-analysis of cross sectional and longitudinal studies. We searched Pubmed, Medline and Embase, all through June 2017. The studies were selected to determine the effect of vitamin D on the parameters of glucose metabolism in diabetic and non-diabetic subjects. Correlation coefficients from all studies were pooled in a random effects meta-analysis. The risk of bias was assessed using Grading of Recommendations Assessment, Development and Evaluation (GRADE) system. We found significant inverse relationship of vitamin D status with glycemic level in both diabetic (r = -0.223, 95% CI = -0.184 to -0.261, p = 0.000) and non-diabetic (r = -0.073, 95% CI = -0.052 to -0.093, p = 0.000) subjects. This meta-analysis concludes that hypovitaminosis D is associated with increased risk of hyperglycemia both in diabetic and non-diabetic subjects. A future strategy for the prevention of impaired glycemic regulation could be individualized supplementation of vitamin D.