Plasma 25-hydroxyvitamin D and progression to diabetes in patients at risk for diabetes: an ancillary analysis in the Diabetes Prevention Program

FoxO1 as a tissue-specific therapeutic target for type 2 diabetes

Forkhead box O (FoxO) proteins are transcription factors that mediate many aspects of physiology and thus have been targeted as therapeutics for several diseases including metabolic disorders such as type 2 diabetes mellitus (T2D). The role of FoxO1 in metabolism has been well studied, but recently FoxO1's potential for diabetes prevention and therapy has been debated. For example, studies have shown that increased FoxO1 activity in certain tissue types contributes to T2D pathology, symptoms, and comorbidities, yet in other tissue types elevated FoxO1 has been reported to alleviate symptoms associated with diabetes. Furthermore, studies have reported opposite effects of active FoxO1 in the same tissue type. For example, in the liver, FoxO1 contributes to T2D by increasing hepatic glucose production. However, FoxO1 has been shown to either increase or decrease hepatic lipogenesis as well as adipogenesis in white adipose tissue. In skeletal muscle, FoxO1 reduces glucose uptake and oxidation, promotes lipid uptake and oxidation, and increases muscle atrophy. While many studies show that FoxO1 lowers pancreatic insulin production and secretion, others show the opposite, especially in response to oxidative stress and inflammation. Elevated FoxO1 in the hypothalamus increases the risk of developing T2D. However, increased FoxO1 may mitigate Alzheimer's disease, a neurodegenerative disease strongly associated with T2D. Conversely, accumulating evidence implicates increased FoxO1 with Parkinson's disease pathogenesis. Here we review FoxO1's actions in T2D conditions in metabolic tissues that abundantly express FoxO1 and highlight some of the current studies targeting FoxO1 for T2D treatment.

Vitamin D and Metabolic Syndrome in Working Age Subjects from an Obesity Clinic

Serum vitamin D (VitD) levels have been inversely related with metabolic syndrome (MetS), although the direct impact of VitD is still debated. This study examined 879 subjects of working age from an obesity and occupational clinic in Milan, Italy. Among these participants, 316 had MetS, while 563 did not. A multiple logistic regression analysis was conducted to determine the odds ratios (ORs) and the corresponding 95% confidence intervals (CIs) for MetS in relation to serum VitD levels. After controlling for age, sex, leisure time physical activity, and body mass index (BMI), individuals with VitD levels between 20 and 29.9 ng/dL, or at least 30 ng/dL, had approximately half the risk of developing MetS (OR: 0.52, 95% CI: 0.32-0.86 and OR: 0.50, 95% CI: 0.25-0.99, respectively) compared to those with VitD levels below 10 ng/dL. This study presents further evidence of the beneficial effect of adequate VitD levels on the risk of MetS in a population of overweight/obese workers, even after adjusting for BMI. This study supports the importance of testing for and-if required-supplementing VitD in individuals with metabolic risk factors.

The Association Between Glycated Hemoglobin (HbA1c) Level and Vitamin D Level in Diabetes Mellitus Patients: A Cross-Sectional Study

BACKGROUND

Prior research has established noteworthy correlations between inadequate glycemic management and a multitude of problems in individuals diagnosed with diabetes mellitus (DM).

METHODS

This is a cross-sectional retrospective study that was conducted at the Jeddah Center for the Care of Diabetes and Blood Pressure Patients, Jeddah, Kingdom of Saudi Arabia. The medical records of patients diagnosed with DM between 2015 and 2022 were identified and reviewed for the purpose of this study. Pearson correlation coefficient was used to examine the correlation between glycated haemoglobin (HbA1c) and vitamin D levels. Multiple linear regression analysis was applied to identify the association between HbA1c and vitamin D levels.

RESULTS

A total of 152 patients were included in this study. The mean HbA1c level for the patients in this study was 8.2% (SD: 1.7). The median vitamin D level for the patients was 20.9 ng/ml (interquartile range (IQR): 13-30.4). More than half of the patients (n= 92; 60.5%) were found to have vitamin D insufficiency. Pearson correlation coefficient identified that there is an inverse correlation between the level of HbA1c and vitamin D level (r= -0.21 (95%CI -0.36 to -0.06; p-value= 0.007). Multiple linear regression analysis (adjusting for age and type of DM) identified that poor glycaemic control has a negative association with vitamin D level (regression coefficient (B) = -0.027; 95%CI -0.053 to - 0.001; p-value= 0.039).

CONCLUSION

Poor glycaemic control is associated with vitamin D deficiency in DM patients. It is recommended that patients with DM adhere to their medications and maintain a healthy lifestyle in order to manage their condition. This will improve their overall health, specifically their vitamin D status.

Development of Machine Learning Models for Predicting Osteoporosis in Patients with Type 2 Diabetes Mellitus-A Preliminary Study

Purpose

Diagnosing osteoporosis in T2DM based on bone mineral density (BMD) remains challenging. We sought to develop prediction models employing machine learning algorithms for use as screening instruments for osteoporosis in T2DM patients.

Patients and Methods

Data were collected from 433 participants and analyzed using nine categorical machine learning algorithms to select features based on demographic and clinical variables. Multiple classification models were compared using the area under the receiver operating characteristic curve (ROC-AUC), accuracy, sensitivity, specificity, the average precision (AP), precision, F1 score, precision-recall curves, calibration plots, and decision curve analysis (DCA) to determine the best model. In addition, 5-fold cross-validation was utilized to optimize the model, followed by an evaluation of feature significance using Shapley Additive exPlanations (SHAP). Using latent class analysis (LCA), distinct subpopulations were identified by constructing several discrete clusters.

Results

In this study, nine feature variables were identified to construct predictive models for osteoporosis in individuals with T2DM. The machine learning algorithms achieved an AP range of 0.444-1.000. The XGBoost model was selected as the final prediction model with an AUROC of 0.940 in the training set, 0.772 in the validation set for 5-fold cross-validation, and 0.872 in the test set. Using SHAP methodology, 25(OH)D was identified as the most important risk factor. Additionally, a 3-Class model was constructed using LCA, which categorized individuals into high, medium, and low-risk groups.

Conclusion

Our study developed a predictive model with high accuracy and clinical validity for predicting osteoporosis in type 2 diabetes patients. We also identified three subpopulations with varying osteoporosis risk using clustering. However, limited sample size warrants cautious interpretation of results, and validation in larger cohorts is needed.

Longitudinal changes in vitamin D concentrations and the association with type 2 diabetes mellitus: the Tromsø Study

AIM

We aimed to investigate the relationship between pre- and post-diagnostic 25-hydroxyvitamin D (25(OH)D) concentrations and type 2 diabetes (T2DM) over a period of 30 years in individuals who developed T2DM compared to healthy controls.

METHODS

This case-control study included 254 participants with blood samples collected at five different time-points (T1-T5) between 1986 and 2016. Of the 254 participants, 116 were diagnosed with T2DM between T3 and T4, and were considered cases; the remaining 138 were controls. Linear mixed regression models were used to examine pre- and post-diagnostic changes in 25(OH)D concentrations, and logistic regression was used to examine associations between these concentrations and T2DM at each time-point.

RESULTS

25(OH)D concentrations at different time-points and the longitudinal change in concentrations differed between cases and controls, and by sex. For women, each 5-nmol/l increase in 25(OH)D concentrations was inversely associated with T2DM at T3 (odds-ratio, OR, 0.79), whereas for men, this same increase was positively associated with T2DM at T1 (OR 1.12). Cases experienced a significant decrease in pre-diagnostic 25(OH)D concentrations (p value < 0.01 for women, p value = 0.02 for men) and a significant increase in post-diagnostic 25(OH)D concentrations (p value < 0.01 for women, p value = 0.01 for men). As such, each 1-unit increase in month-specific z-score change between T1 and T3 was significantly inversely associated with T2DM (OR 0.51 for women, OR 0.52 for men), and each such increase between T3 and T5 was significantly positively associated with T2DM in women (OR 2.48).

CONCLUSIONS

25(OH)D concentrations seem to be affected by disease progression and type 2 diabetes diagnosis.

Adherence to the Dietary Approaches to Stop Hypertension (DASH) Eating Pattern Reduces the Risk of Head and Neck Cancer in American Adults Aged 55 Years and Above: A Prospective Cohort Study

OBJECTIVES

Dietary Approaches to Stop Hypertension (DASH) pattern has been found to aid in the reduction of obesity, oxidative stress, and chronic inflammation, which are all strongly linked to the development of head and neck cancer (HNC). Nevertheless, no epidemiological studies have investigated the association between this dietary pattern and HNC risk. This study was conducted with the purpose of bridging this gap in knowledge.

DESIGN

A prospective cohort study involving 98,459 American adults aged 55 years and older.

SETTING AND PARTICIPANTS

Data were drawn from the Prostate, Lung, Colorectal, and Ovarian (PLCO) Trial. In the present study, participants with dependable energy intake data who furnished baseline and dietary history information were identified as the study population.

METHODS

Diet was assessed by food frequency questionnaires and the DASH score was calculated to assess each participant's adherence to DASH eating pattern. Cox proportional hazards models were used to calculate multivariable adjusted hazard ratios (HRs) and 95% confidence intervals (CIs) for the occurrence of HNC. To visualize the variation in cancer risk for HNC and its subtypes across the entire spectrum of DASH scores, restricted cubic spline plots were utilized. Additionally, a series of predefined subgroup analyses were performed to identify potential effect modifiers, and several sensitivity analyses were conducted to assess the stability of the findings.

RESULTS

During a follow-up period of 871,879.6 person-years, 268 cases of HNC were identified, comprising 161 cases pertaining to oral cavity and pharynx cancers, as well as 96 cases of larynx cancer. In the fully adjusted model, adherence to the DASH diet was associated with a remarkable 57% reduction in the risk of HNC when comparing extreme quartiles (HR quartile 4 vs 1: 0.43; 95% CI: 0.28, 0.66; P for trend < 0.001). The restricted cubic spline plots demonstrated a linear dose-response relationship between the DASH score and the risk of HNC as well as its subtypes. Subgroup analysis revealed that the protective effect of the DASH diet against HNC was particularly pronounced in individuals with lower daily energy intake. The primary association remained robust in the sensitivity analysis.

CONCLUSIONS

In American middle-aged and older population, adherence to the DASH diet may help prevent HNC, particularly for individuals with lower daily energy intake.

Vitamin D deficiency in patients with diabetes and its correlation with water fluoride levels

Chronic exposure to fluoride through drinking water has been linked to insulin resistance and resulting type 2 diabetes mellitus (T2DM). Here, we aim to study the impact of water fluoride levels on blood glucose and vitamin D levels. A hospital-based study was conducted on diabetic patients (n = 303) at All India Institute of Medical Sciences (AIIMS), Raebareli outstation patient department (OPD). The relationship between vitamin D or fasting blood glucose levels (BGLs) with water fluoride levels was estimated through Spearman's rank correlation. We found a significant negative correlation between water fluoride and vitamin D levels [r_s = -0.777, p-value < 0.001] and a positive correlation between water fluoride and fasting BGLs [r_s = 0.178, p-value <0.05]. The participants residing in fluoride-endemic areas (F > 1.5 mg/L) had higher odds of severe vitamin D deficiency (odds ratio: 5.07, 95% CI: 1.9-13.2, p-value = 0.0009). The results demonstrate that vitamin D deficiency and fasting BGLs are significantly associated with water fluoride levels. This study signifies the role of fluoride toxicity in poor glycemic control and derived vitamin D deficiency. Vitamin D supplementation and the application of standard household water purification devices are recommended to tackle vitamin D deficiency in fluoride-endemic areas.

The modification of individual factors on association between serum 25(OH)D and incident type 2 diabetes: Results from a prospective cohort study

Several epidemiological studies have suggested an association between low vitamin D status and increased risk for type 2 diabetes (T2D). This study aimed to explore the dose-response relationship of serum 25-hydroxyvitamin D [25(OH)D] concentrations with incident T2D and the interaction between serum 25(OH)D with individual factors on T2D risk. A total of 1,926 adults without diabetes (mean age: 52.08 ± 13.82 years; 42% men) were prospectively followed for 36 months. Cox proportional hazards model and restricted cubic spline analysis were performed to assess the association and dose-response relationship between serum 25(OH)D and T2D incidence. Both additive and multiplicative interactions were calculated between serum 25(OH)D and individual factors. The net reclassification index (NRI) was used to evaluate the improvement of risk prediction of T2D by adding serum 25(OH)D to traditional risk factors. There were 114 new T2D cases over a mean follow-up of 36 months. Serum 25(OH)D was not associated with T2D incidence, and no significant dose-response relationship was found in the total population. However, stratified analyses suggested a non-linear inverse relationship among individuals with baseline fasting plasma glucose (FPG) <5.6 mmol/L (P _overall = 0.061, P _non-linear = 0.048). And a significant multiplicative interaction was observed between serum 25(OH)D and FPG on T2D risk (P = 0.005). In addition, we found a significant additive interaction of low serum 25(OH)D with older age (RERI = 0.897, 95% CI: 0.080-1.714; AP = 0.468, 95% CI: 0.054-0.881), male (AP = 0.441, 95% CI: 0.010-0.871), and insufficient physical activity (RERI = 0.875, 95% CI: 0.204-1.545; AP = 0.575, 95% CI: 0.039-1.111) on T2D risk. Significant additive interactions were also observed between vitamin D deficiency/insufficiency with male, overweight/obesity, and insufficient physical activity on T2D risk. Moreover, adding low serum 25(OH)D to a model containing established risk factors yielded significant improvements in the risk reclassification of T2D (NRI = 0.205, 95% CI: 0.019-0.391). Our results indicated a non-linear relationship of serum 25(OH)D concentrations with T2D risk among individuals with normal FPG and additive interactions of serum 25(OH)D with gender, overweight/obesity, and physical activity on T2D risk, suggesting the importance of outdoor exercise.

The association of serum vitamin D with incident diabetes in an African American population

BACKGROUND

Incident diabetes risk is inversely proportional to 25-hydroxyvitamin D [25(OH)D] levels among non-Hispanic white but is unclear among African American (AA) populations. Serum 25(OH)D2 may be an important component of total 25(OH)D among AA populations due to higher levels of melanin.

OBJECTIVE

To assess the association of serum 25(OH)D with incident diabetes among AAs and stratify by detectable 25(OH)D2.

DESIGN

Serum 25(OH)D2 and 25(OH)D3 were collected from 2000 to 2004 among AA participants in the Jackson Heart Study. A cosinor model was used to adjust for the seasonality of 25(OH)D3; 25(OH)D3 and 25(OH)D2 were combined to ascertain total 25(OH)D. Incident diabetes (fasting glucose ≥126 mg/dl, use of diabetes drugs, or HbA1c ≥6.5%) was assessed over 12 years among adults without diabetes at baseline. Participants with missing baseline covariates or diabetes follow-up were excluded. Hazard ratios (HR) were estimated using Cox modeling, adjusting for age, sex, education, occupation, smoking, physical activity, alcohol use, aldosterone, and body-mass index.

RESULTS

Among 3311 adults (mean age 53.3 years, 63% female) 584 participants developed diabetes over a median of 7.7 years. After adjustment, 25(OH)D ≥20 compared to <12 ng/ml was associated with a HR 0.78 (95% CI: 0.61, 1.00). Among participants with detectable 25(OH)D2 and 25(OH)D3 (n = 1671), 25(OH)D ≥ 20 ng/ml compared to <12 ng/ml was associated with a 35% (HR 0.65, 95% CI: 0.46, 0.91) lower risk of diabetes.

CONCLUSIONS

Higher levels of 25(OH)D may be protective against the development of diabetes among AA individuals, particularly among those with detectable 25(OH)D2 and 25(OH)D3.

The Role of Forkhead Box O in Pathogenesis and Therapy of Diabetes Mellitus

Type 2 diabetes is a disease that causes numerous complications disrupting the functioning of the entire body. Therefore, new treatments for the disease are being sought. Studies in recent years have shown that forkhead box O (FOXO) proteins may be a promising target for diabetes therapy. FOXO proteins are transcription factors involved in numerous physiological processes and in various pathological conditions, including cardiovascular diseases and diabetes. Their roles include regulating the cell cycle, DNA repair, influencing apoptosis, glucose metabolism, autophagy processes and ageing. FOXO1 is an important regulator of pancreatic beta-cell function affecting pancreatic beta cells under conditions of insulin resistance. FOXO1 also protects beta cells from damage resulting from oxidative stress associated with glucose and lipid overload. FOXO has been shown to affect a number of processes involved in the development of diabetes and its complications. FOXO regulates pancreatic β-cell function during metabolic stress and also plays an important role in regulating wound healing. Therefore, the pharmacological regulation of FOXO proteins is a promising approach to developing treatments for many diseases, including diabetes mellitus. In this review, we describe the role of FOXO proteins in the pathogenesis of diabetes and the role of the modulation of FOXO function in the therapy of this disease.

Association of Serum 25-Hydroxyvitamin D With Cardiovascular Outcomes and All-Cause Mortality in Individuals With Prediabetes and Diabetes: Results From the UK Biobank Prospective Cohort Study

OBJECTIVE

To examine the associations of circulating 25-hydroxyvitamin D (25[OH]D) concentrations with cardiovascular disease (CVD) and all-cause mortality in individuals with prediabetes and diabetes from the large population-based UK Biobank cohort study.

RESEARCH DESIGN AND METHODS

A total of 67,789 individuals diagnosed with prediabetes and 24,311 with diabetes who had no CVD or cancer at baseline were included in the current study. Serum 25(OH)D concentrations were measured at baseline. Cox proportional hazard models were used to calculate hazard ratios (HRs) and 95% CIs for cardiovascular outcomes and mortality after 10-14 years.

RESULTS

After multivariable adjustment, higher serum 25(OH)D levels were significantly and nonlinearly associated with lower risk of cardiovascular outcomes and all-cause mortality among participants with prediabetes and diabetes (all P nonlinearity < 0.05). Compared with those in the lowest category of 25(OH)D levels (<25 nmol/L), participants with prediabetes in the highest category of 25(OH)D levels (≥75 nmol/L) had a significant association with lower risk of cardiovascular events (HR 0.78; 95% CI 0.71-0.86), coronary heart disease (CHD) (HR 0.79; 95% CI 0.71-0.89), heart failure (HR 0.66; 95% CI 0.54-0.81), stroke (HR 0.75; 95% CI 0.61-0.93), CVD mortality (HR 0.43; 95% CI 0.32-0.59), and all-cause mortality (HR 0.66; 95% CI 0.58-0.75). Likewise, these associations with cardiovascular events, CHD, heart failure, CVD mortality, and all-cause mortality were observed among participants with diabetes, except for stroke.

CONCLUSIONS

These findings highlight the importance of monitoring and correcting vitamin D deficiency in the prevention of CVD and mortality among adults with prediabetes and diabetes.

Vitamin D deficiency associated with risk of prediabetes among older adults: Data from the National Health and Nutrition Examination Survey (NHANES), 2007-2012

AIM

To examine the association between vitamin D (25(OH)D) deficiency and risk of prediabetes in Americans 50+ years of age.

MATERIALS AND METHODS

This was a cross-sectional analysis of NHANES (2007-2012) subjects aged 50+ years, free of kidney/liver diseases and diabetes. Prediabetes was defined as: HbA1c level 5.7%-6.4%, or fasting plasma glucose level 100-125 mg/dL, or Oral Glucose Tolerance Test result 140-199 mg/dL, with no laboratory value in the diabetic range. The comparison group had normal glucose tolerance (NGT) with no marker in the prediabetes/diabetes range. Total serum 25(OH)D levels were deficient at <50 nmol/L, insufficient 50-75 nmol/L, and sufficient >75 nmol/L. Logistic regression included strata, cluster and weight variables. Models were adjusted for body mass index (BMI), ethnicity, age and gender.

RESULTS

The final sample was 2286 adults, predominantly White (80.4%) and female (56.6%), with a mean age of 62.3 years. Within the sample, 1387 had prediabetes (59.1%) and 899 were NGT (40.9%). Individuals classified within a lower serum vitamin D category were more likely to have prediabetes (p = 0.03). Those with 25(OH)D deficiency were more likely to have prediabetes compared to 25(OH)D sufficient individuals (crude OR = 1.48, 95% CI 1.15-1.91), and this association remained significant after adjustment for ethnicity, BMI, age and gender (aOR = 1.39, 95% CI 1.02-1.89). There was no effect modification by BMI, gender or ethnicity.

CONCLUSIONS

Vitamin D status was associated with risk of prediabetes in this sample of Americans 50+ years of age. Future research should seek to understand the potential mechanistic relationship between vitamin D and prediabetes.

Sirt1 Mediates Vitamin D Deficiency-Driven Gluconeogenesis in the Liver via mTorc2/Akt Signaling

As an active form of vitamin D (VD), 1,25-dihydroxyvitamin D (1,25(OH)₂D₃) is involved in the development of many metabolic diseases, such as diabetes, autoimmune diseases, and tumours. While prospective epidemiological studies have consistently implicated VD deficiency in the regulation of glucose metabolism and insulin sensitivity, the specific mechanism remains unclear. Here, we generated 1α(OH)ase-null mice (targeted ablation of the 25-hydroxyvitamin D 1α hydroxylase enzyme) and found that these mice developed hepatic glucose overproduction, glucose intolerance, and hepatic insulin resistance accompanied by reduced Sirtuin 1 (Sirt1) expression. The chromatin immunoprecipitation (ChIP) and a luciferase reporter assay revealed that 1,25(OH)₂D₃-activated VD receptor (VDR) directly interacted with one VD response element (VDRE) in the Sirt1 promoter to upregulate Sirt1 transcription, triggering a cascade of serine/threonine kinase (AKT) phosphorylation at S473 and FOXO1 phosphorylation at S256. This phosphorylation cascade reduced the expression of gluconeogenic genes, eventually attenuating glucose overproduction in the liver. In addition, a signaling pathway was found to modulate gluconeogenesis involving VDR, Sirt1, Rictor (a component of mTOR complex 2 [mTorc2]), AKT, and FOXO1, and Sirt1 and FOXO1 were identified as key modulators of dysregulated gluconeogenesis due to VD deficiency.

Investigating the Efficiency of Vitamin D Administration with Buccal Spray in the Treatment of Vitamin D Deficiency in Children and Adolescents

OBJECTIVE

The aim of this study was to evaluate the efficiency of a buccal spray form of vitamin D compared to single oral dose (stoss therapy) and oral drops therapy in the treatment of vitamin D deficiency.

METHODS

Ninety healthy children and adolescents (3-18 years) with vitamin D deficiency [serum level of 25-hydroxyvitamin D (25(OH) D) <12 ng/mL] were randomized to receive vitamin D3 buccal spray (2000 U, n=30, group 1) for six weeks, oral drops (2000 U, n=30, group 2) for six weeks and a single oral dose (300 000 U) vitamin D3 (n=30, group 3). Serum calcium, phosphorus, alkaline phosphatase, parathyroid hormone and 25(OH)D levels of the patients were measured at baseline and after the treatment on the 42^nd day.

RESULTS

All three groups had a significant increase in serum 25(OH)D concentrations (p<0.001). In group 1, baseline mean 25(OH)D was 8.0±0.41 ng/mL, which rose to 22.1 (17.8-28.2) ng/mL after treatment with a mean increase of 15.6±1.3 ng/mL. Similarly in group 2, baseline, post-treatment and mean increase in 25(OH)D concentrations were 7.9±0.45 ng/mL, 24.4 (20.6-29.6) ng/mL and 17.3±1.1 ng/mL while for group 3 these values were 7.6±0.47 ng/mL, 40.3 (29.4-58.4) ng/mL and 34.3±3.2 ng/mL, respectively.

CONCLUSION

We conclude that vitamin D3 supplementation with buccal spray and oral drops is equally effective in terms of raising vitamin D concentrations in short-term treatment of vitamin D deficiency.

Serum 25-hydroxyvitamin D and Metabolic Parameters in Healthy Korean Adults: Korean National Health and Nutrition Examination Survey VI

Purpose

Studies investigating the association between vitamin D and metabolic parameters have reported inconsistent results depending on the characteristics of the subjects. We aimed to investigate the association between vitamin D levels and various metabolic indicators in healthy Korean adults by using nationally representative data.

Methods

A total of 3640 participants were included after excluding subjects who were ≤19 years of age and had a history of treatment for dyslipidemia, hypertension, or diabetes and a history of other chronic diseases such as liver and kidney diseases. After dividing the 25-hydroxyvitamin D (25(OH)D) level into quartiles, the risk of having each metabolic parameter higher than the median value was determined according to the 25(OH)D quartile by using regression analysis.

Results

In a multivariate regression analysis, a higher 25(OH)D quartile tended to have a significantly lower risk of having a triglyceride (TG) level higher than the median value (103.1 mg/dl). As the quartile increased, the risk of having a waist circumference or body mass index higher than the median value also decreased, but the difference was not statistically significant. No significant changes were observed in fasting glucose or glycated hemoglobin level according to quartile.

Conclusion

We demonstrated that subjects with a higher 25(OH)D quartile exhibited a significantly lower risk of having a TG level higher than the median value in a representative Korean population. More evidence from a prospective study on whether vitamin D supplementation improves serum TG levels in healthy adults is needed.

Vitamin D Supplementation for Prevention of Type 2 Diabetes Mellitus: To D or Not to D?

CONTEXT

Over the last decade, vitamin D has emerged as a risk determinant for type 2 diabetes and vitamin D supplementation has been hypothesized as a potential intervention to lower diabetes risk. Recently, several trials have reported on the effect of vitamin D supplementation on diabetes prevention in people with prediabetes.

EVIDENCE ACQUISITION

A comprehensive literature review was performed using PubMed, Embase, and ClinicalTrials.gov to identify: (1) recent meta-analyses of longitudinal observational studies that report on the association between blood 25-hydroxyvitamin D (25[OH]D) level and incident diabetes, and (2) clinical trials of adults with prediabetes that have reported on the effect of vitamin D supplementation on incident diabetes.

EVIDENCE SYNTHESIS

Longitudinal observational studies report highly consistent associations between higher blood 25(OH)D levels and a lower risk of incident diabetes in diverse populations, including populations with prediabetes. Trials in persons with prediabetes show risk reduction in incident diabetes with vitamin D supplementation. In the 3 large trials that were specifically designed and conducted for the prevention of diabetes, vitamin D supplementation, when compared with placebo, reduced the risk of developing diabetes by 10% to 13% in persons with prediabetes not selected for vitamin D deficiency.

CONCLUSIONS

Results from recent trials are congruent with a large body of evidence from observational studies indicating that vitamin D has a role in modulating diabetes risk. Participant-level meta-analysis of the 3 largest trials should provide a more refined estimate of risk reduction and identify patient populations that are likely to benefit the most from vitamin D supplementation.

Low Vitamin D Levels and Frailty Status in Older Adults: A Systematic Review and Meta-Analysis

Serum vitamin D deficiency is widespread among older adults and is a potential modifiable risk factor for frailty. Moreover, frailty has been suggested as an intermediate step in the association between low levels of vitamin D and mortality. Hence, we conducted a systematic review of the literature and meta-analysis to test the possible association of low concentrations of serum 25-hydroxyvitamin D (25(OH)D), a marker of vitamin D status, with frailty in later life. We reviewed cross-sectional or longitudinal studies evaluating populations of older adults and identifying frailty by a currently validated scale. Meta-analyses were restricted to cross-sectional data from studies using Fried’s phenotype to identify frailty. Twenty-six studies were considered in the qualitative synthesis, and thirteen studies were included in the meta-analyses. Quantitative analyses showed significant differences in the comparisons of frail (standardized mean difference (SMD)—1.31, 95% confidence interval (CI) (−2.47, −0.15), p = 0.0271) and pre-frail (SMD—0.79, 95% CI (−1.58, −0.003), p = 0.0491) subjects vs. non-frail subjects. Sensitivity analyses reduced heterogeneity, resulting in a smaller but still highly significant between-groups difference. Results obtained indicate that lower 25(OH)D levels are significantly associated with increasing frailty severity. Future challenges include interventional studies testing the possible benefits of vitamin D supplementation in older adults to prevent/palliate frailty and its associated outcomes.

The Relationship Between Vitamin D Deficiency and Glycated Hemoglobin Levels in Patients with Type 2 Diabetes Mellitus

PURPOSE

The aims of this study were to determine the relationship between 25-hydroxyvitamin D [25(OH) D] and glycated hemoglobin (HbA1c) levels in male and female patients with type 2 diabetes mellitus (T2DM).

PATIENTS AND METHODS

The participants were adults diagnosed with T2DM recruited from Hebei General Hospital. Patient information and information regarding blood indicators were collected. The subjects were divided into no vitamin D deficiency group [25(OH) D >20 ng/mL] and vitamin D deficiency group [25(OH) D <20 ng/mL], and these groups were then further subdivided into male-only or female-only subgroups. And then, the subjects were divided into male group and female group in different 25(OH) D levels.

RESULTS

HbA1c levels in the vitamin D deficiency group were significantly higher than those in the no vitamin D deficiency group for all subjects. The same was true for female patients but not for male patients. There was no difference in HbA1c levels between male and female patients with T2DM, regardless of 25(OH) D deficiency. A negative correlation existed between 25(OH) D and HbA1c in all subjects, as well as in the male-only and female-only subgroups. Vitamin D deficiency was associated with high HbA1c levels before and after adjusting for confounding factors in all participants and in the female-only subgroup, but not in the male-only subgroup.

CONCLUSION

This study confirmed that vitamin D deficiency was related with high HbA1c levels in patients with T2DM, and this relationship differs between female and male patients.

Current Knowledge Regarding the Interaction Between Oral Bone Metabolic Disorders and Diabetes Mellitus

Diabetes mellitus, a major chronic disease affecting human health, has been increasing in prevalence in recent years. Diabetes mellitus can cause bone metabolic disorders in patients, leading to osteoporosis, a higher risk of traumatic fracture, and other bone diseases. Bone metabolic disorders in the oral cavity principally manifest as periodontitis, loss of alveolar bone, and failure of implant osseointegration. In recent years, numerous studies have shown that there is a complex interaction between bone metabolic disorders and diabetes mellitus. This paper reviews the adverse effects of diabetes on oral bone metabolism disorders such as alveolar osteoporosis and bone loss in patients with periodontitis, discusses the potential mechanisms of diabetic bone loss, and suggests potential ways to prevent and treat oral bone loss in patients with diabetes mellitus.

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.

The prevalence of vitamin D deficiency among patients with type 2 diabetes seen at a referral hospital in Kenya

Introduction

The prevalence of diabetes mellitus is rising at an alarming rate, calling for more insights into its pathogenetic mechanisms, and other factors involved in its progression. The prevalence of vitamin D deficiency is higher in diabetic compared to non-diabetic patients, and is associated with poor glycaemic control. This has not been documented among diabetic patients in Kenya. Aims: to determine the prevalence of hypovitaminosis D among type 2 diabetic patients at Kenyatta National Hospital in Nairobi, Kenya.

Methods

We recruited type 2 diabetic patients on follow-up at Kenyatta National Hospital. Measurements of height, weight and waist/hip ratios were taken. We drew 6mls of peripheral blood to determine vitamin D, zinc and HbA1c levels.

Results

A total of 151 participants were recruited, with 69.5% females and mean age of 58.2 years. Hypertension was found in 72.8% of the participants, and obesity in 37.7%. The mean HbA1c levels were 8.46%, and 62.9% had poor glycaemic control. The mean vitamin D level was 31.40ng/ml. Vitamin D deficiency and insufficiency was found in 38.4% and 21.9% of the participants respectively. We found a significant inverse correlation between vitamin D and glycaemic control (r = -0.09, p = 0.044) and vitamin D and BMI (r = - 0.145, p = 0.045).

Conclusion

In this study population on long-term follow-up for diabetes, there was high prevalence of vitamin D deficiency. This forms a basis for further management of patients with poor glycaemic control. Further studies are needed to document the causal association between poor glycaemic control and vitamin D deficiency.

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.

Urinary metabolic profiles after vitamin D2 versus vitamin D3 supplementation in prediabetes

Aim

To assess the potential biological differences between vitamin D₂ and D₃ using urinary metabolite profiles in response to vitamin D₃ or D₂ supplementation.

Method

Subjects consisted of 29 subjects with impaired fasting glucose and/or impaired glucose tolerance. Subjects were randomized into two groups, vitamin D₂ (20,000 IU weekly, n = 14) or vitamin D₃ (15,000 IU weekly, n = 15). Urine and serum samples were taken at two different time points for each subject (at baseline and at 12 weeks). Urinary metabolite profiling was performed by liquid chromatography electrospray ionization quadrupole time-of-flight mass spectrometry (LC-ESI-QTOF-MS). Serum calcium was analyzed on an automated biochemical analyzer and serum intact parathyroid hormone was determined by electrochemiluminescence immunoassay.

Results

At baseline, there was no statistically significant difference in clinical characteristics including age, gender, body mass index, waist circumference and 25-hydroxyvitamin D (25(OH)D) levels between the 2 groups. Weekly administration of 20,000 U D₂ for 12 weeks resulted in comparable 25(OH)D concentrations as compared to weekly 15,000 U D₃ supplementation (97.8 ± 305 vs. 96.8 ± 3.4 nmol/L, p = 0.84). No difference in serum calcium (2.3 ± 0.03 vs. 2.2 ± 0.03 nmol/L, p = 0.52) or intact parathyroid hormone (5.3 ± 0.3 vs. 4.9 ± 0.5 pmol/L, p = 0.54) at 12 weeks was found. Principle component analysis did not reveal apparent segregation of metabolites according to D₂ or D₃ supplementation. Moreover, using partial least square regression, no apparent separation between the D₂ and the D₃ group was found. No important metabolite influencing the separation of the D₂ from the D₃ group was found using variables importance on projection analysis.

Conclusions

At comparable circulating 25(OH)D concentrations, vitamin D₂ or D₃ supplementation does not appear to result in different urinary metabolite profiles. Our finding does not support a biological difference between vitamin D₂ and D₃.

Vitamin D receptor rs7975232, rs731236 and rs1544410 single nucleotide polymorphisms, and 25-hydroxyvitamin D levels in Egyptian children with type 1 diabetes mellitus: effect of vitamin D co-therapy

Purpose: We aimed to examine the possible association role of vitamin D and vitamin D receptor (VDR) single nucleotide polymorphisms (SNPs) in type 1 diabetes mellitus (T1DM) development, glycemic control and complications among a cohort of Egyptian children. Subjects and methods: A prospective case-control study has been conducted on 50 Egyptian children with T1DM who were comparable with 50 controls. Vitamin D and HbA1c were measured. VDR-SNPs [ApaI (rs7975232), TaqI (rs731236) and BsmI (rs1544410)] detection was done by polymerase chain reaction through restriction fragment length polymorphism (PCR-RFLP) technique. Vitamin D supplements were given to the included T1DM children with low vitamin D and reassessments of both HbA1c% and 25(OH)D serum levels were performed in those children three months later. Results: Eighty percent of the included diabetic patients have poor glycemic control. Vitamin D was deficient in 68% and insufficient in 16% of diabetic patients. Significant improvements in both vitamin D and glycemic status among T1DM children, who have low vitamin D and received vitamin D supplementations. There were significantly negative correlations between serum levels of vitamin D with both HbA1c % (r= -0.358, P˂0.05) and daily insulin dose (r=-0.473, P˂0.05). Compared with controls, T1DM children presented more commonly with ApaI a allele (OR: 2.87; 95%CI: 1.39-5.91, P˂0.05) and BsmI b allele (OR: 4.38; 95%CI: 2.30-8.33, P˂0.05). TaqI t allele wasn't significantly differing among patients and controls (P˃0.05). Aa+aa and Bb+bb genotypes were significantly higher among T1DM vs the controls (OR: 3.08;, 95%CI: 1.33-7.15, P˂0.05 and OR: 9.33; 95%CI: 3.61-24.17, P˂0.05respectively). Conclusion: ApaI and BsmI were associated with risk of T1DM development among Egyptian children. Low vitamin D status was frequently occurring among T1DM with significant improvement in the glycemic control of such children when adding vitamin D supplements to the standard insulin therapy.

Vitamin D Status, Calcium Intake and Risk of Developing Type 2 Diabetes: An Unresolved Issue

The relationship between vitamin D status, calcium intake and the risk of developing type 2 diabetes (T2D) is a topic of growing interest. One of the most interesting non-skeletal functions of vitamin D is its potential role in glucose homeostasis. This possible association is related to the secretion of insulin by pancreatic beta cells, insulin resistance in different tissues and its influence on systemic inflammation. However, despite multiple observational studies and several meta-analyses that have shown a positive association between circulating 25-hydroxyvitamin D concentrations and the risk of T2D, no randomized clinical trials supplementing with different doses of vitamin D have confirmed this hypothesis definitively. An important question is the identification of what 25-hydroxyvitamin D levels are necessary to influence glycemic homeostasis and the risk of developing T2D. These values of vitamin D can be significantly higher than vitamin D levels required for bone health, but the currently available data do not allow us to answer this question adequately. Furthermore, a large number of observational studies show that dairy consumption is linked to a lower risk of T2D, but the components responsible for this relationship are not well established. Therefore, the importance of calcium intake in the risk of developing T2D has not yet been established. Although there is a biological plausibility linking the status of vitamin D and calcium intake with the risk of T2D, well-designed randomized clinical trials are necessary to answer this important question.

Vitamin D receptor gene polymorphisms and 25(OH) vitamin D: Lack of association to glycemic control and metabolic parameters in type 2 diabetic Egyptian patients

Background

Vitamin D deficiency and vitamin D receptor (VDR) gene polymorphisms have been linked to type 2 diabetes mellitus (T2DM) and its metabolic parameters, however there are conflicting results therefore we aimed to evaluate VDR gene polymorphisms (Fok1, Bsm1 and Taq1) and vitamin D status in Egyptian patients with T2DM and to detect the associations of these polymorphisms to their metabolic parameters and glycemic control.

Methods

50 patients with T2DM and 50 healthy age matched control subjects were enrolled. FBG, 2 h -PPG, fasting lipids, Hb A1c, calcium, phosphorus, urea, creatinine, ALT, AST were measured. BMI has calculated. Serum 25 hydroxy vitamin D [25(OH)D] has measured by ELISA. VDR gene polymorphisms detection has done by polymerase chain reaction through restriction fragment length polymorphism (PCR-RFLP) technique.

Results

Our study has shown lower mean levels of 25(OH)D in patients with T2DM (28.54 ± 10.02) in comparison with control subjects (44.65 ± 7.19), p < 0.001. Vitamin D insufficiency was more prevalent in T2DM 58% than in healthy control subjects 4%. There were statistically significant differences between patients with type 2 diabetes and controls regarding the distribution of FokI genotypes and alleles (p = 0.005) and non significant difference regarding Bsm1 and Taq1. Neither VDR gene polymorphisms nor 25(OH)D showed significant association with glycemic control, fasting lipids and BMI in patients with T2DM.

Conclusions

Vitamin D deficiency is prevalent in Egyptian patients with T2DM. Associations were found only between VDR FokI gene polymorphism and susceptibility to Egyptian patients with T2DM. Non significant differences in VDR gene polymorphisms distribution has found regarding glycemic control and metabolic parameters.

Oxidative-Nitrative Stress and Poly (ADP-Ribose) Polymerase Activation 3 Years after Pregnancy

Background

Oxidative-nitrative stress and poly (ADP-ribose) polymerase activation have been previously observed in healthy and gestational diabetic pregnancies, and they were also linked to the development of metabolic diseases. The aim of the present study was to examine these parameters and their correlation to known metabolic risk factors following healthy and gestational diabetic pregnancies.

Methods

Fasting and 2 h postload plasma total peroxide level, protein tyrosine nitration, and poly (ADP-ribose) polymerase activation were measured in circulating leukocytes three years after delivery in women following healthy, "mild" (diet-treated) or "severe" (insulin-treated) gestational diabetic pregnancy during a standard 75 g OGTT. Nulliparous women and men served as control groups.

Results

Fasting plasma total peroxide level was significantly elevated in women with previous pregnancy (B = 0.52 ± 0.13; p < 0.001), with further increase in women with insulin-treated gestational diabetes (B = 0.36 ± 0.17; p < 0.05) (R² = 0.419). Its level was independently related to previous pregnancy (B = 0.47 ± 0.14; p < 0.01) and current CRP levels (B = 0.06 ± 0.02; p < 0.05) (R² = 0.306).

Conclusions

Elevated oxidative stress but not nitrative stress or poly (ADP-ribose) polymerase activation can be measured three years after pregnancy. The increased oxidative stress may reflect the cost of reproduction and possibly play a role in the increased metabolic risk observed in women with a history of severe gestational diabetes mellitus.

The association of VDR polymorphisms and type 2 diabetes in older people living in community in Santiago de Chile

INTRODUCTION

Several polymorphisms have been associated with obesity and type 2 diabetes in different populations.

OBJECTIVE

To investigate the frequencies of a genetic polymorphism of vitamin D receptor (FokI and BsmI) in patients with T2D.

METHODS

The case-control study was conducted in 138 patients with T2D and 172 control subjects, men and women (60-79 years old). The genotype and allele frequency determination of VDR polymorphisms were determined in these subjects.

RESULTS

The frequency of the C allele of the FokI polymorphism was significantly higher in the T2D group than in healthy subjects (p = 0.025). The frequencies of the BsmI variant were similar in subjects with and without T2D (p = 0.747). Consistent with these data, there was an association of the C allele with T2D (OR = 1.74, 95% CI = 1.003-3.084, p = 0.036), but not the AG + GG variants for BsmI (OR = 1.02, 95% CI = 0.635-1.649, p = 0.916). We can observe a significant association between carrier of the T > C variant of FokI and type 2 diabetes, adjusted for vitamin D, age, obesity (overweight and obesity), seasonality, sex and Homa-IR. Here, we show a significant association between the FokI polymorphisms (TC + CC) and T2D with an odds ratio of 1.9001 (95% CI (1.0970-3.6838), p = 0.041).

CONCLUSION

Our study suggests that the C allele (TC + CC) of the VDR-FokI gene is a possible risk factor for T2D in older people living in a community in Santiago de Chile.

Plasma 25-hydroxyvitamin D concentration and risk of type 2 diabetes and pre-diabetes: 12-year cohort study

BACKGROUND

It has been reported that higher plasma 25-hydroxyvitamin D is associated with lower risk of type 2 diabetes. However the results to date have been mixed and no adequate data based on a cohort are available for the high end of the normal range, above approximately 32 ng/ml or 80 nmol/L.

METHODS

We performed a cohort study of 903 adults who were known to be free of diabetes or pre-diabetes during a 1997-1999 visit to a NIH Lipid Research Centers clinic. Plasma 25(OH)D was measured at Visit 8 in 1977-1979. The mean age was 74 years. The visit also included fasting plasma glucose and oral glucose tolerance testing. Follow-up continued through 2009.

RESULTS

There were 47 cases of diabetes and 337 cases of pre-diabetes. Higher 25(OH)D concentrations (> 30 ng/ml) were associated with lower hazard ratios (HR) for diabetes: 30-39 ng/ml or 75-98 nmol/L: HR = 0.31, 95% CI = 0.14-0.70; for 40-49 ng/ml or 100-122 nmol/L: HR = 0.29, CI = 0.12-0.68; for > 50 ng/ml or 125 nmol/L: HR = 0.19, CI = 0.06-0.56. All HRs are compared to < 30 ng/ml or 75 nmol/L. There was an inverse dose-response gradient between 25(OH)D concentration and risk of diabetes with a p for trend of 0.005. Each 10 ng/mL or 25 nmol/L higher 25(OH)D concentration was associated with a HR of 0.64, CI = 0.48-0.86. 25(OH)D concentrations were more weakly inversely associated with pre-diabetes risk, and the trend was not significant.

CONCLUSION

Further research is needed on whether high 25(OH)D might prevent type 2 diabetes or transition of prediabetes to diabetes.

Lower vitamin D levels in Saudi pregnant women are associated with higher risk of developing GDM

BACKGROUND

Gestational diabetes mellitus (GDM) has serious consequences such as increased risks of preeclampsia, macrosomia and cesarean delivery. Even though the mechanistic basis of GDM has not been completely understood, several risk factors have been identified and one of these is vitamin D. However, the link between vitamin D deficiency and development of GDM is yet to be proven with certainty.

METHODS

This study aimed to investigate the link between the incidence of GDM and serum vitamin D level in pregnant women of Saudi Arabia. 515 Saudi women (ages 18-46) in their 24-28th week of pregnancy, visiting various hospitals of Riyadh, participated in this study. Serum vitamin D and various biochemical and anthropometric parameters were determined in the first trimester and the recruits were screened for GDM by OGTT according to IADPSG criteria in their 2nd trimester. The association between vitamin D deficiency and development of GDM was calculated based on odds ratio of the incidence of GDM among vitamin D deficient and normal women.

RESULTS

In this study cohort of 515 pregnant women, in the first trimester vitamin D deficiency (< 50 nmol/l) was detected in 425 (82.5%). On their 2nd visit (2nd trimester), 116 (27.7%) were diagnosed with GDM out of 419 with OGTT, according to IADPSG criteria. GDM risk was significantly higher among vitamin D deficient than non-deficient women (Odds Ratio: 2.87; Confidence Interval: 1.32-6.25; P = 0.008) even after adjusting for season, sun exposure and vitamin D intake (OR: 2.9; CI: 1.07-7.89). Of the various anthropometric and biochemical parameters, the GDM women differed significantly from non-GDM women with respect to serum levels of triglycerides (in mmol/l) (1.3 ± 0.6; 1.5 ± 0.6, p = 0.018) and fasting glucose (in mmol/l) [4.7 (4.3-5.2); 5.1 (4.6-5.6), p < 0.01]. Also, fasting glucose level in the 2nd trimester correlated inversely to serum vitamin D level determined during the 1st trimester (r = - 0.121; p = 0.014).

CONCLUSIONS

Results of our study reveal a significantly higher risk of development of GDM among pregnant women having deficient vitamin D status.

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

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

Vitamin D Deficiency and Immune Disorders in Combined Endocrine Pathology

Introduction: Combined endocrine pathology is a serious healthcare problem in Ukraine. This prospective study assessed the blood levels of 25-hydroxyvitamin D [25(OH)D] and markers of immune function in response to vitamin D intervention in patients with type 1 and type 2 diabetes mellitus (T1DM and T2DM, respectively) and autoimmune thyroiditis (AIT). Objective: This study evaluated the relationship between the metabolic and immune status of DM + AIT patients with respect to their vitamin D status and changes after vitamin D₃ supplementation. Material and Methods: Patients with type 1 or type 2 DM in combination with AIT and decreased circulating levels of 25(OH)D were divided into two groups of 30 patients each. All patients with AIT were euthyroid and receiving hormonal replacement therapy. The levels of carbohydrate and fat metabolism markers, Immunologic markers, namely, Th1-type cytokines [interferon (IFN)-γ, tumor necrosis factor (TNF)-α, interleukin (IL)-2, IL-6, IL-12], Th2-type cytokines (IL-4, IL-5), IL-10, and IL-17 were measured before and after vitamin D₃ supplementation. The vitamin D status was assessed according to the level of 25(OH)D. Results: Patients with combined endocrine disorders (DM and AIT) with a decreased vitamin D status had significantly increased background concentrations of Th1-type cytokines and reduced concentrations of Th2-type cytokines (IL-4 and IL-5), IL-10, and IL-17. The results of our study showed that vitamin D₃ supplementation in patients with T1DM and T2DM reduced the concentrations of the inflammatory Th1-type cytokines and increased the levels of Th2-type cytokines. Conclusion: The presence of two endocrine diseases, aggravated by decreased circulating levels of 25(OH)D, leads to disorders wherein the immune status is markedly changed. These decreased levels of 25(OH)D contribute to an autoimmune inflammatory process and to the progression of complications in addition to the metabolic disorders. A vitamin D intervention resulted in significant changes in the blood levels of 25(OH)D that are related to parameters of autoimmunity and glucose metabolism. Vitamin D₃ supplementation should be considered for the prevention and treatment of combined endocrine pathology.

Non-musculoskeletal benefits of vitamin D

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

Relationship Between Vitamin D Deficiency and the Components of Metabolic Syndrome in Patients with Morbid Obesity, Before and 1 Year After Laparoscopic Roux-en-Y Gastric Bypass or Sleeve Gastrectomy

BACKGROUND

Vitamin D deficiency (VDD) is associated with obesity and metabolic syndrome (MS). After bariatric surgery (BS), high rates of VDD often persist and some patients are refractory to the resolution of comorbidities. The aim of the present study is to analyse the relationship between the levels of vitamin D and the persistence of MS components at 12 months after BS, according to the surgical technique used.

METHODS

We performed a retrospective study of 46 patients undergoing BS: 23 underwent laparoscopic Roux-en-Y gastric bypass (LRYGBP) and 23 laparoscopic sleeve gastrectomy (LSG). These patients had an average BMI of 45 kg/m² (34-63). Levels of vitamin D were classified as deficient (<20 ng/dl), insufficient (20-30 ng/dl) or normal (>30 ng/dl) and analysed in relation to the components of MS (high blood pressure (HBP), dyslipidaemia (DL) and type 2 diabetes mellitus (T2DM) preoperatively and 12 months after surgery.

RESULTS

VDD was observed in 77% of the patients prior to surgery. There were no significant associations between predisposing factors and baseline vitamin D. After surgery, plasma levels of vitamin D increased in both groups, but only 18% of the patients achieved normal values. Both groups had achieved significant improvements in MS components. Thus, 63% of all the patients achieved complete resolution of HBP, 54% that of DL and 77% that of T2DM. Moreover, MS was present in 11% of the patients, compared to 63% at baseline, and the MS resolution rate was 83%, with no significant differences between LRYGBP and LSG.

CONCLUSIONS

There is a relationship between VDD and persistence of MS, and particularly so with T2DM. VDD could represent a predictor of MS persistence at 12 months after surgery.

Association of Glycosylated Hemoglobin Levels With Vitamin D Status

Background

The discovery of vitamin D is one of medicine’s great achievements. Despite all the positive evidence emerging about the beneficial effect of vitamin D, we still find many are vitamin D deficient. The purposes of this study were to examine the association between serum 25-hydroxyvitamin D (25(OH)D) and glycosylated hemoglobin (HbA1c) levels, to test the hypothesis that lower 25(OH)D levels are associated with poorer glucose control in diabetes mellitus (DM) patients and to investigate the effect of vitamin D supplementation on HbA1c levels.

Methods

This was a prospective observational cohort study of all patients with type 1 and type 2 diabetes (above 12 years) who attended the outpatient clinics of a tertiary center in Riyadh. HbA1c and vitamin D levels were recorded prior to supplementation and after 9 months of supplementation with vitamin D. All patients were divided into four groups according to their vitamin D level and an association between 25(OH)D and HbA1c was tested.

Results

Results showed that 73.1% of the patients had 25(OH)D levels < 50 nmol/L. We observed lowering of HbA1c after vitamin D supplementation (from mean HbA1c of 10.55 to 7.70). We found HbA1c to be inversely related to serum vitamin D levels (r = -0.14 (P < 0.0000002) before supplementation and -0.16 (P < 0.000001) after supplementation with vitamin D).

Conclusions

Advising patients with higher HbA1c to test their vitamin D level and correct any deficiency will result in better blood glucose control and benefit the patient’s overall health.

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.

No effect of vitamin D supplementation on cardiovascular risk factors in subjects with metabolic syndrome: a pilot randomised study

Introduction

Patients with metabolic syndrome (MetS) may have lower 25-hydroxyvitamin D (25(OH)VitD) serum levels compared with non-MetS individuals. Vitamin D (VitD) deficiency is associated with various cardiovascular disease (CVD) risk factors. Yet, the effect of VitD supplementation on MetS remains uncertain. Our aim was to examine the effect of VitD supplementation on CVD risk factors in MetS subjects.

Material and methods

This pilot study had a PROBE (prospective, randomised, open-label, blinded end-point) design. Fifty patients with MetS were included and randomised either to dietary instructions (n = 25) (control group) or dietary instructions plus VitD 2000 IU/day (n = 25) (VitD group) for 3 months. This study is registered in ClinicalTrials.gov (NCT01237769).

Results

In both groups a similar small weight reduction was achieved. In the VitD group serum 25(OH)VitD levels significantly increased by 91% (from 16.0 (3.0–35.0) to 30.6 (8.4–67.0) ng/ml, p < 0.001), while in the control group no significant change was observed (from 10.0 (4.0–39.6) to 13.0 (3.5–37.0) ng/ml). In both groups triglycerides, high-density lipoprotein cholesterol, low-density lipoprotein cholesterol, fasting glucose, haemoglobin A_1c, homeostasis model assessment index and diastolic blood pressure did not significantly change. Systolic blood pressure decreased by 3.7% (from 134 ±14 to 129 ±13 mm Hg, p = 0.05) in the VitD group, while it decreased by 1.5% (from 132 ±13 to 130 ±16 mm Hg, p = NS) in the control group (p = NS between groups). In the VitD group serum 25(OH)VitD increase was negatively correlated with SBP decrease (r = –0.398, p = 0.049).

Conclusions

VitD supplementation (2000 IU/day) did not affect various CVD risk factors in patients with MetS.

Determination of Vitamin D Status in a Population of Ecuadorian Subjects

INTRODUCTION

Vitamin D is a preprohormone known to play a key role in phosphocalcic metabolism; its main source comes from the synthesis at the skin level by ultraviolet (UV) radiation.

OBJECTIVE

The purpose of this study was to determine the levels of vitamin D in an Ecuadorian population.

MATERIALS AND METHODS

Retrospective study of Ecuadorian subjects from the city of Guayaquil, who had an initial study of 25 (OH)-D serum, as the indicator of Vitamin D status, in the period of 2015-2016.

RESULTS

A total of 269 Ecuadorian subjects were analyzed, with a mean age of 54.73 ± 16.58; 85% (229) were females and 15% (41) males; mean vitamin D was 27.29 ± 10.12 ng/dl [6.41-88.74]; 70% of the population showed levels below 30 ng/dL of vitamin D, whereas only 30% (81) had normal values. 69% (185) had levels between 29 and 10 ng/dl and 1% (3) levels below 10 ng/dl. High levels of vitamin D were evidenced in the summer months in relation to the winter months.

CONCLUSION

It is evident that, despite the location of Ecuador and the intensity of UV rays it receives throughout the year, Ecuadorian subjects have insufficient levels of vitamin D.

Association of Vitamin D Receptor Gene Polymorphism in Adults With Type 2 Diabetes in the Kashmir Valley

OBJECTIVES

Approx 1 billion people across various ethnic and age groups have vitamin D deficiency. The high prevalence of such a deficiency is an imperative public health issue because hypovitaminosis D is an autonomous risk factor for mortality in the general population. Beyond bone integrity and calcium homeostasis, it is involved in numerous physiologic and pathologic processes. The role of vitamin D in the pathogenesis and prevention of type 2 diabetes mellitus has sparked universal interest.

METHODS

This hospital-based case-control study was designed to study the association between 25-hydroxy vitamin D (25[OH]D) levels and the vitamin D receptor (VDR) gene polymorphism with diabetes and to evaluate their roles as risk factors for diabetes. 100 cases and controls were taken. 25(OH)D levels were analyzed by the chemilumenescence method using a Siemens ADVIA Centaur analyzer. Genomic DNA was extracted and Taq-1 and Bsm-1 genotyping in the VDR gene was done by using the polymerase chain reaction followed by restriction fragment length polymorphism (PCR-RFLP).

RESULTS

25(OH)D levels of patients with diabetes were significantly lower than those of controls (19.26±0.95 ng/mL vs. 25.49±1.02 ng/mL; p=0.001). 25(OH)D levels were found to be inversely associated with glycated hemoglobin percentages in cases (r²=0.74). The results suggested that the single nucleotide polymorphisms Taq-1 t(T) allele and b (G allele) in Bsm-1 might be a susceptibility allele for diabetes in the Kashmiri population.

CONCLUSIONS

VDR gene polymorphisms appear to be an important genetic determinant in the progression of diabetes. Considering the important predisposition risk factor, we observed that Taq-1 and Bsm-1 were strongly associated with diabetes in northern Indians. But requires further study as a probable genetic risk marker for diabetes.

Special considerations for vitamin D in the south Asian population in the UK

The human requirement for vitamin D is achieved primarily through the synthesis of this prehormone in the skin during exposure to ultraviolet B (UVB) radiation, with only a minor contribution from the diet, year round. Achieving optimal vitamin D status is therefore largely dependent upon adequate exposure of the skin to sunlight, however, the length of exposure required varies with latitude and season, and is also dependent upon skin pigmentation, with darker skin requiring greater exposure than fair skin due to the protective effects of melanin against UVB radiation. In northern European latitudes, where UVB radiation between the months of October and March is of insufficient intensity for the synthesis of vitamin D via this route, vitamin D deficiency is a public health concern, particularly for south Asian diaspora and other dark-skinned ethnic minority communities. The consequences of vitamin D deficiency include poor bone health, including rickets and osteomalacia. In addition, there is increasing awareness of an important role for vitamin D in the development and progression of chronic diseases, including type 2 diabetes, which is prevalent in south Asian populations. The aim of this review is to examine some of the most recent reports of vitamin D status in south Asian diaspora communities, and to explore its impact on bone health. In addition, we will examine the putative association between type 2 diabetes and vitamin D deficiency in south Asian populations and the current guidelines for treatment of vitamin D deficiency of south Asians in primary care settings.

Study of Glycated Haemoglobin (HbA1c) In Non-Diabetic Subjects with Subclinical Hypothyroidism

INTRODUCTION

India has the higher prevalence of prediabetes, diabetes and hypothyroidism. Subclinical Hypothyroidism (SH) is more prevalent in the females than in the males. Studies have shown the elevated HbA1c in the non-diabetic hypothyroid patients. SH is defined by normal serum triiodothyronine (T₃), thyroxine (T₄) levels and serum Thyroid Stimulating Hormone (TSH) level falling between 4.2 to 10 mU/L.

AIM

To study the HbA1c level in the non-diabetic SH patients and to compare the HbA1c level with the controls.

MATERIALS AND METHODS

This case-control study was conducted on 200 subjects. A total of 100 subjects of the SH without diabetes were selected on the basis of the serum TSH (> 4.2 to < 10 mU/L), Fasting Blood Sugar (FBS) (< 110 mg/dl) level and another 100 age and sex matched normal healthy individuals were selected as the control. The HbA1c levels were measured using Immunoturbidimetry method in the Cobas Integra 400 plus. An independent t-test is applied to find out the statistically significant difference in the level of HbA1c in the case and the control groups.

RESULTS

Subjects with the non-diabetic SH had a significant higher level (5.70±0.35 %) of the HbA1c than the controls (5.26±0.17 %) (p<0.0001). There was no significant difference between the cases and the controls for the age, sex, FBS, vitamin D₃, Haemoglobin (Hb), serum T₃ and serum T₄ levels.

CONCLUSION

Our data suggest that the non-diabetic subjects with SH show misleadingly high levels of the HbA1c. Therefore, the effect of altered levels of the serum TSH on the HbA1c must be considered when interpreting the HbA1c for the diagnosis of diabetes in the SH patients.

Association of serum 25-hydroxyvitamin D3 with adipokines and inflammatory marker in persons with prediabetes mellitus

BACKGROUND

The association of vitamin D status and inflammation prediabetes mellitus (PreDM) individuals has not been investigated. We investigated the association of serum 25-hydroxyvitamin D₃ (25(OH) D₃) with adipokines and inflammatory markers in persons with PreDM.

METHODS

In this cross-sectional study, we stratified 418 nondiabetic subjects as having PreDM or normal fasting glucose (NFG), and divided PreDM or NFG subjects into vitamin D sufficient, vitamin D insufficient and vitamin D deficient subgroups. 25(OH) D₃ concentrations were determined by HPLC. Serum tumor necrosis factor-α (TNF-α), interleiukin-6 (IL-6) and high-sensitivity C-reactive protein (hs-CRP), adiponectin, leptin and resistin were measured by ELISA.

RESULTS

In the PreDM group, compared with those in the vitamin D sufficient subgroup, vitamin D insufficient subgroup and vitamin D deficient subgroup had higher concentrations of hs-CRP and leptin (P<0.05). In the PreDM-deficient or PreDM-insufficient subgroup, mean hs-CRP and leptin concentration was higher than in the PreDM-sufficient, NFG-deficient, NFG-insufficient and NFG-sufficient subgroups (P<0.05). Serum 25(OH) D₃ concentrations were inversely associated with hs-CRP and leptin concentrations after adjusted the BMI only in the PreDM group (P<0.05). At the multivariate analysis, hs-CRP and leptin were the major determinant of 25(OH) D₃ concentration (β=-0.174 and β=-0.171, respectively).

CONCLUSIONS

25(OH) D₃ status in PreDM individuals was inversely correlated with concentrations of hs-CRP and leptin, suggesting their involvement in the inflammation response between vitamin D status and PreDM.

25-Hydroxyvitamin D Status and Risk for Colorectal Cancer and Type 2 Diabetes Mellitus: A Systematic Review and Meta-Analysis of Epidemiological Studies

Epidemiological evidence suggests an association between low vitamin D status and risk for various outcomes including cardiovascular diseases, cancer, and type 2 diabetes mellitus (T2DM). Analyzing serum 25-hydroxyvitamin D [25(OH)D] is the most established means to evaluate an individual's vitamin D status. However, cutoff values for 25(OH)D insufficiency as well as for optimal 25(OH)D levels are controversial. This systematic review critically summarizes the epidemiological evidence regarding 25(OH)D levels and the risk for colorectal cancer and T2DM. The meta-analytical calculation revealed a pooled relative risk (RR) of 0.62 (CI 0.56-0.70; I² = 14.7%) for colorectal cancer and an RR of 0.66 (CI 0.61-0.73; I² = 38.6%) for T2DM when comparing individuals with the highest category of 25(OH)D with those in the lowest. A dose-response analysis showed an inverse association between 25(OH)D levels and RR for both outcomes up to concentrations of about 55 ng/mL for colorectal cancer and about 65 ng/mL for T2DM. At still higher 25(OH)D levels the RR increases slightly, consistent with a U-shaped association. In conclusion, a higher 25(OH)D status is associated with a lower risk for colorectal cancer and T2DM; however, this advantage is gradually lost as levels increase beyond 50-60 ng/mL.

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.

The role of vitamin D, obesity and physical exercise in regulation of glycemia in Type 2 Diabetes Mellitus patients

AIM

The aims of this study were to determine the role of vitamin D, obesity and physical exercise in the regulation of glycemia in Type 2 Diabetes Mellitus patients in a highly consanguineous population.

DESIGN

Case and control study.

SETTING

The survey was carried out at the Hamad General Hospital and Primary Health Care (PHC) centers in the State of Qatar.

SUBJECTS

The study was conducted from November 2012 to June 2014 among subjects above 30 years of age. Of the 2224 registered with diagnosed diabetes and free diseases attending Hamad General Hospital and PHC centers agreed and gave their consent to study.

METHODS

Questionnaire included socio-demographic variables, body mass index (BMI), consanguinity, lifestyle habits, family history of diabetes, blood pressure and development of diabetes complications such as retinopathy, nephropathy, and neuropathy were collected at regular intervals throughout the follow-up. Univariate and multivariate statistical analysis were performed.

RESULTS

There were statistically significant difference between patients with diabetic and control in terms of ethnicity (p=0.012), level of education (p=0.002), occupation (p<0.001), monthly income (p<0.001), BMI(p=0.024), sport activity (p=0.018), cigarette smoking (p<0.001), consanguinity (p=0.029) and family history of Diabetes Mellitus (p<0.001) and co-morbidity hypertension (p=0.041). Further, the biochemistry values in the studied subjects with T2DM compared to healthy controls and the study revealed that serum Vitamin D, BMI, fasting glucose level, calcium, HbA1c, total cholesterol HDL, LDL, bilirubin, triglycerides, uric acid and blood pressure systolic and diastolic were higher in T2DM compared to their counterparts. Multivariate logistic regression showed that vitamin D deficiency ng/mL, Family History of T2DM, BMI (kg/m²) hypertension, consanguinity, income, mother occupation, ethnicity, educational level and Lack of physical exercise variables were significant predictors of diabetes. In the group of Diabetes Mellitus Type 2 patients, 39.3% as opposed to 51.2% in the control group had vitamin D deficiency, 25(OH) D3 levels≤10ng/ml (p<0.001). In the group of Diabetes Mellitus Type 2 patients, 34.6% as opposed to 37.9% in the control group had vitamin D insufficiency, 25(OH)D3 levels <20ng/ml (p < 0.001). In the group of Diabetes Mellitus Type 2 patients, 22.8% as opposed to 14.2% in the control group had vitamin D sufficiency, 25(OH)D3 levels >30 10ng/ml (p < 0.001).

CONCLUSION

Vitamin D, family history of diabetes, consanguinity marriages' and hereditary gene-environment interactions and physical exercise may also contribute to the current diabetes epidemic in Qatari's Arab populations.

Rationale and design of Diabetes Prevention with active Vitamin D (DPVD): a randomised, double-blind, placebo-controlled study

INTRODUCTION

Recent research suggests that vitamin D deficiency may cause both bone diseases and a range of non-skeletal diseases. However, most of these data come from observational studies, and clinical trial data on the effects of vitamin D supplementation on individuals with pre-diabetes are scarce and inconsistent. The aim of the Diabetes Prevention with active Vitamin D (DPVD) study is to assess the effect of eldecalcitol, active vitamin D analogue, on the incidence of type 2 diabetes among individuals with pre-diabetes.

METHODS AND ANALYSIS

DPVD is an ongoing, prospective, multicentre, randomised, double-blind and placebo-controlled outcome study in individuals with impaired glucose tolerance. Participants, men and women aged ≥30 years, will be randomised to receive eldecalcitol or placebo. They will also be given a brief (5-10 min long) talk about appropriate calorie intake from diet and exercise at each 12-week visit. The primary end point is the cumulative incidence of type 2 diabetes. Secondary endpoint is the number of participants who achieve normoglycaemia at 48, 96 and 144 weeks. Follow-up is estimated to span 144 weeks.

ETHICS AND DISSEMINATION

All protocols and an informed consent form comply with the Ethics Guideline for Clinical Research (Japan Ministry of Health, Labour and Welfare). The study protocol has been approved by the Institutional Review Board at Kokura Medical Association and University of Occupational and Environmental Health. The study will be implemented in line with the CONSORT statement.

TRIAL REGISTRATION NUMBER

UMIN000010758; Pre-results.

Associations between Vitamin D Status and Type 2 Diabetes Measures among Inuit in Greenland May Be Affected by Other Factors

OBJECTIVE

Epidemiological studies have provided evidence of an association between vitamin D insufficiency and type 2 diabetes. Vitamin D levels have decreased among Inuit in Greenland, and type 2 diabetes is increasing. We hypothesized that the decline in vitamin D could have contributed to the increase in type 2 diabetes, and therefore investigated associations between serum 25(OH)D3 as a measure of vitamin D status and glucose homeostasis and glucose intolerance in an adult Inuit population.

METHODS

2877 Inuit (≥18 years) randomly selected for participation in the Inuit Health in Transition study were included. Fasting- and 2hour plasma glucose and insulin, C-peptide and HbA1c were measured, and associations with serum 25(OH)D3 were analysed using linear and logistic regression. A subsample of 330 individuals who also donated a blood sample in 1987, were furthermore included.

RESULTS

After adjustment, increasing serum 25(OH)D3 (per 10 nmol/L) was associated with higher fasting plasma glucose (0.02 mmol/L, p = 0.004), 2hour plasma glucose (0.05 nmol/L, p = 0.002) and HbA1c (0.39%, p<0.001), and with lower beta-cell function (-1.00 mmol/L, p<0.001). Serum 25(OH)D3 was positively associated with impaired fasting glycaemia (OR: 1.08, p = 0.001), but not with IGT or type 2 diabetes.

CONCLUSIONS

Our results did not support an association between low vitamin D levels and risk of type 2 diabetes. Instead, we found weak positive associations between vitamin D levels and fasting- and 2hour plasma glucose levels, HbA1c and impaired fasting glycaemia, and a negative association with beta-cell function, underlining the need for determination of the causal relationship.

Effect of vitamin D supplementation on insulin resistance and glycaemic control in prediabetes: a systematic review and meta-analysis

AIMS

To evaluate the effect of vitamin D on insulin resistance and glycaemic control in prediabetes.

METHODS

A literature search was conducted of MEDLINE, the Cochrane Library, Cumulative Index to Nursing and Allied Health Literature (CINAHL), Scopus, Web of Science and www.clinicaltrials.gov, together with a historical search through the reference lists of relevant articles until end of June 2014. Studies were included if they were randomized controlled trials of vitamin D or vitamin D analogues in prediabetes and if they reported homeostatic model assessment of insulin resistance or 2-h plasma glucose after oral glucose tolerance test. Treatment effect was estimated according to mean difference in the changes from baseline of homeostatic model assessment of insulin resistance, 2-h oral glucose tolerance test plasma glucose, fasting plasma glucose and HbA1c between vitamin D and control groups. Meta-analysis of eligible studies was performed.

RESULTS

A total of 10 randomized controlled trials were included. Vitamin D did not significantly improve homeostatic model assessment of insulin resistance and 2-h oral glucose tolerance test plasma glucose: the mean differences were -0.06 (95% CI -0.36 to 0.24) and -0.23 mmol/l (95% CI -0.65 to 0.19), respectively. Subgroup analysis suggested that vitamin D improved homeostatic model assessment of insulin resistance in a subgroup with baseline 25-hydroxyvitamin D ≥ 50 nmol/l [mean difference -0.59 (95% CI -1.14 to -0.04); P = 0.03] and improved 2-h oral glucose tolerance test plasma glucose in the subgroup with baseline 25-hydroxyvitamin D < 50 nmol/l [mean difference -0.68 mmol/l (95% CI -1.35 to -0.01); P = 0.05]. Vitamin D significantly reduced fasting plasma glucose and HbA1c levels. The mean differences were -0.10 mmol/l (95% CI -0.18 to -0.03), P = 0.006 and -1 mmol/mol (95% CI -2 to 0), P = 0.008, respectively.

CONCLUSIONS

No beneficial effect of vitamin D in improving insulin resistance was identified.