Vitamin D and Incidence of Prediabetes or Type 2 Diabetes: A Four-Year Follow-Up Community-Based Study

Surveillance and Evaluation of Vitamin D Nutrition and Its Health Impact in Chinese Older Adults

Vitamin D is an essential fat-soluble vitamin for humans and vitamin D deficiency (VDD) affects all age groups, with older adults being at high risk of VDD. A deficiency in vitamin D has been associated with a range of health concerns in older adults, including osteomalacia and osteoporosis. Additionally, there is limited evidence suggesting that VDD may be associated with increased risk of developing cognitive impairment, muscle-wasting disorders, cardiovascular disease, type 2 diabetes mellitus, and mortality. This review synthesizes the latest research advances in China and abroad to provide detailed information on the current status of vitamin D nutritional monitoring, causes of deficiency, health risks, and proposed intake for reducing risk of diet-related noncommunicable diseases in the Chinese older adults.

The interplay between vitamin D status, subclinical inflammation, and prediabetes

Vitamin D's role extends beyond classical calcium and phosphate homeostasis to encompass a pivotal influence on immune modulation and metabolic health. The mechanisms by which vitamin D exerts these effects involve its conversion to hormonally active calcitriol, which binds intracellular vitamin D receptors, initiating various downstream cascades. In this review, we tease out the evidence showing the relationship between vitamin D deficiency and prediabetes within the context of subclinical inflammation, with a special focus on the novel monocyte-to-HDL ratio (MHR), a novel inflammatory marker reflecting subclinical inflammation. This was based on a thorough literature review using reputable databases covering the period from 1980 to 2024. In light of this, we discuss calcitriol's anti-inflammatory effects and consequently link vitamin D deficiency to both overt and subclinical inflammation. Additionally, the utility of several biomarkers, notably MHR, in investigating this association is also discussed. We further reviewed the role of vitamin D deficiency in precipitating prediabetes and type 2 diabetes mellitus (T2DM) via insulin resistance, decreased insulin synthesis and secretion, and subclinical inflammation. Taken together, this mini review highlights that vitamin D deficiency is significantly associated with subclinical inflammation, playing a critical role in the development of prediabetes and the progression to T2DM. Addressing vitamin D deficiency through appropriate interventions may serve as a preventative measure against the development of prediabetes and T2DM.

Association between Vitamin D Deficiency and Prediabetes Phenotypes: A Population-Based Study in Henan, China

The evidence remains inconsistent regarding whether vitamin D deficiency (VDD) increases the risk of prediabetes. This study aimed to examine whether there is sex-specific association between VDD and impaired fasting glucose (IFG) or impaired glucose tolerance (IGT) in Henan. The data were sourced from the survey of chronic diseases and nutrition in Henan. Multinomial logistic regression models based on complex sampling design and weight were developed to estimate the odds ratio (OR) and confidence interval (95%CI) for measuring the association between VDD and IFG/IGT. The prevalence rate of IGT in men was 20.1% in the VDD group, significantly higher than that in the non-VDD group (10.5%), but no significant difference was observed in women between the VDD and non-VDD groups; there were no significant differences in IFG prevalence between the VDD and non-VDD groups in either men or women. It was found that the association between VDD and IGT was statistically significant in men. The adjusted OR (95%CI) of VDD was 1.99 (1.24-3.19) for IGT in men and 14.84 (4.14-53.20) for IGT in men having a family history of DM. Thus, men with VDD were more likely to live with IGT than those without VDD, especially for men having a family history of diabetes.

Investigating the relationship between vitamin-D deficiency and glycemia status and lipid profile in nondiabetics and prediabetics in Saudi population

Vitamin D deficiency increases the risk of developing diabetes, dyslipidemia, and other chronic diseases. We aimed to investigate the relationship between vitamin D deficiency, glycemic levels, and lipid profiles in individuals with prediabetes and nondiabetes. This observational cross-sectional study was conducted on 249 adults who were divided into 2 groups based on the American Diabetes Association classification: nondiabetics and prediabetics. The serum vitamin D levels, lipid profiles, fasting blood glucose levels, hemoglobin A1c levels, fasting insulin levels, and insulin resistance (IR) were evaluated. The prevalence of vitamin D deficiency in all participants was 30.9%, and mean vitamin D levels were significantly [P = .0004] lower in prediabetics, who were more common in females. Furthermore, prediabetics had significantly higher serum triglycerides [P = .0006], and significantly lower serum high-density lipoprotein levels [P = .0148] than those nondiabetics. Serum cholesterol and low-density lipoprotein levels did not differ significantly between the 2 groups. 31.4% of all participants were overweight and 40.2% were obese. Furthermore, there was a strong correlation between vitamin D levels and IR and body mass indices ≥ 25 in prediabetics [r = -0.92] [P < .001]. Finally, vitamin D levels had a significant inverse relationship with glycemic parameters and IR, particularly in obese participants, but there was no significant relationship with lipid profile. In conclusion, vitamin D deficiency is common in females, regardless of whether they are prediabetics, but is more prevalent in prediabetics. Vitamin D deficiency is associated with high triglycerides and low high-density lipoprotein levels, but there were no significant changes in total cholesterol or low-density lipoprotein levels. Furthermore, vitamin D levels were negatively correlated with both fasting blood glucose and hemoglobin A1c levels, and its deficiency was strongly associated with IR especially in obese patients despite there being no significant correlation with blood lipids.

Short-Term Effects of Fruit Juice Enriched with Vitamin D3, n-3 PUFA, and Probiotics on Glycemic Responses: A Randomized Controlled Clinical Trial in Healthy Adults

This study aimed to determine the glycemic index (GI) of a commercial mixed fruit juice (apple, orange, grape, and pomegranate; FJ) fortified with vitamin D3 or n-3 polyunsaturated fatty acids (PUFA) or probiotics, and their combination, and their effects on glycemic responses and salivary insulin concentrations. In a randomized controlled, double-blind, crossover study, 11 healthy participants (25 ± 2 years; five women; body mass index = 23 ± 1 kg/m²) were randomly assigned to receive five types of FJs [vitD (with vitamin D3); n-3 (with n-3 PUFA); probiotics (with Lacticaseibacillus casei Shirota and Lacticaseibacillus rhamnosus GG); vitD-n-3-probiotics FJ (combination of vitD3-n-3-probiotics), control (regular FJ)], all containing 50 g available carbohydrate, and glucose as reference drink. All FJs provided low GI values (control: 54; vitD3: 52; n-3: 51; probiotics: 50; and vitD-n-3-probiotics combination: 52, on glucose scale). Compared to the FJ control, the enriched FJs produced different postprandial glycemic and insulinemic responses and affected satiety scores. All FJ types, regardless of the added biofunctional ingredients, attenuated postprandial glycemic responses, which may offer advantages to glycemic control.

Effect of Vitamin D and/or Calcium Supplementation on Pancreatic β-Cell Function in Subjects with Prediabetes: A Randomized, Controlled Trial

So far, the potential role of vitamin D in β-cell function remains a matter of debate. Therefore, a randomized, placebo-controlled trial (RCT) was conducted to evaluate the effect of a vitamin D supplement with or without calcium on β-cell function in a Chinese population with prediabetes. Two hundred and forty-three subjects were randomly assigned in a 2-by-2 factorial-design RCT to receive either 1600 IU/day vitamin D₃ with/or 500 mg/day calcium for 24 weeks. The results showed that oral administration of vitamin D and calcium could increase the secretion of insulin. Vitamin D-insufficient individuals displayed an increment in the disposition index (adjusted change = 0.31, 95%CI: 0.07, 0.56) after treatment by vitamin D + calcium. It illustrated that supplementation with vitamin D and calcium might improve the function of pancreatic β-cell in prediabetes with low serum 25(OH)D levels. However, further studies are needed to confirm the findings. Given the low vitamin D content in natural foods, it is necessary to fortify processed foods with vitamin D.

Vitamin D insufficiency and its association with adipokines and atherogenic indices in patients with metabolic syndrome: A case-control study

INTRODUCTION

Vitamin D deficiency is one of the most common nutritional disorders in most countries of the world. The present study was designed and implemented with the aim of investigating the relationship between vitamin D deficiency and the level of adipokines, atherogenesis indicators and factors related to metabolic syndrome.

METHODS

This case-control study was done on 195 patients with metabolic syndrome aged 20-50 y who attended the health centers in Zabol County, northeast Iran, between April 2021 and January 2022. Anthropometric and biochemical parameters were measured for all subjects with standard methods. To determine serum 25(OH)D levels, we used enzymatic linked immunosorbent assay (ELISA) kits. Atherogenic index of plasma (AIP) was calculated as log (TG/HDL-c). The visceral adiposity index (VAI) and the lipid accumulation product (LAP) were estimated according to standard formulas.

RESULTS AND DISCUSSION

Participants in the case group had lower serum levels of 25(OH)D compared to controls (19.8 ± 6.2 ng/ml vs. 41.2 ± 9.7ng/ml, P<0.001). We found that the mean serum levels of fasting blood sugar (P=0.023) and TG (P=0.008) as well as HOMA-IR (P=0.023) were significantly higher in the cases compared to controls. Also, patients with MetS and vitamin D insufficiency (cases) had higher AIP (P=0.040) and LAP (P=0.012) than controls. Furthermore, serum 25(OH)D levels showed significant inverse correlations with serum RBP-4 and a positive correlation with serum omentin-1 concentrations. The results of the present study showed that vitamin D deficiency correlated with some of the cardiometabolic risk factors among the patients with MetS.

Relationship Between Vitamin D Levels and β Cell Function and Insulin Resistance

Background This study aimed to determine the relationship between vitamin D levels and β cell function and insulin resistance in patients with diabetes, glucose tolerance disorder, or impaired fasting glucose. Methodology A total of 75 outpatients (55 females and 20 males) between the ages of 30 and 65 years were included in the study. There were 25 healthy individuals, 25 individuals with prediabetes, and 25 individuals with diabetes. The Homeostasis Model Assessment (HOMA) score was used to evaluate insulin resistance. Results The mean levels of vitamin 25(OH)D among the groups included in the study were 35 ± 16.9 nmol/L in the control group, 44.5 ± 34.5 nmol/L in the prediabetes group, and 35.7 ± 13.1 nmol/L in the diabetes group. There were no significant differences. The mean level of vitamin 1.25(OH)₂D₃ was 15.95 ± 8 pg/mL in the control group, 18.4 ± 7.5 pg/mL in the prediabetes group, and 21.5 ± 7.9 pg/mL in the diabetes group. While the levels of vitamin 25(OH)D were similar between the groups, the levels of vitamin 1,25(OH)₂D₃  were significantly higher in the diabetes group. Considering all individuals, no significant difference was found between the vitamin 25(OH)D and glucose levels at minutes 0, 30, 60, 90, and 120. While there was a significant positive relationship between the 1,25(OH)₂D₃ vitamin and glucose levels at minutes 0, 30, 60, and 90, there was no significant relationship between the levels at minute 120. When the 1,25(OH)₂D₃ vitamin and HOMA insulin resistance and HOMA β scores were compared, a significant positive relationship was found between the 1,25(OH)₂D₃ vitamin and HOMA β levels. Conclusions In our study, there was no significant difference between the groups (control, prediabetes, and diabetes) in 25(OH)D levels. Similarly, there was no significant relationship between the 25(OH)D levels and insulin sensitivity and resistance between the groups. The positive relationship identified between the 1,25(OH)₂D₃ vitamin levels and the glucose concentration at minutes 0, 30, 60, and 90 and the higher 1,25(OH)₂D₃ vitamin levels in the diabetes group compared to the control group in our study can be interpreted as the effort of the organism to prevent glucose-induced β-cell apoptosis.

Evaluation of miRNA-143 and miRNA-145 Expression and Their Association with Vitamin-D Status Among Obese and Non-Obese Type-2 Diabetic Patients

OBJECTIVE

Growing epidemics of type-2 diabetes mellitus (T2DM) and obesity have become a serious health concern. Since miRNAs and vitamin levels affect the development and progression of numerous pathogenic diseases, including diabetes, the present study aimed to evaluate miRNA-143 and miRNA-145 expression and vitamin-D status among obese and non-obese T2DM patients.

METHODS

The study included 100 clinically confirmed newly diagnosed obese and non-obese T2DM cases and 100 healthy subjects. Total RNA was extracted from collected blood samples and 100 ng of RNA was used for cDNA synthesis, then TaqMan assay was performed to evaluate the miRNA-143 and miRNA-145 relative expression.

RESULTS

T2DM cases with hypertension (4.08 fold, p=0.01; 5.36 fold, p=0.009), fatigue (5.07 fold, p=0.04; 5.32 fold, p=0.03) and blurred vision (5.15 fold, p=0.01) showed higher miRNA-143 and miRNA-145 relative expression compared with their counterparts, respectively. A positive correlation was observed between miRNA-143 and miRNA-145 expression and decreased vitamin-D status in T2DM had significant association with impaired blood glucose fasting (p=0.001) and HDL level (p<0.0001). Obese T2DM cases showed higher miRNA-143 and miRNA-145 expression compared with their counterparts. Vitamin-D deficient T2DM cases had higher miRNA-143 and miRNA-145 expression (5.69 fold, 5.91 fold) compared with insufficient (4.27 fold, p=0.03; 4.61 fold, p=0.03) and sufficient (4.08 fold, p=0.002; 4.29 fold, p=0.003). ROC curve for miRNA-143 and miRNA-145 between obese T2DM vs non-obese T2DM cases, at best possible cutoff value of 4.39 fold, 4.0 fold showed increased miRNA-143 and miRNA-145 expression, the sensitivity and specificity were 85%, 88% and 61%, 53% respectively (AUC=0.83, p<0.0001; AUC=0.81, p<0.0001).

CONCLUSION

Higher miRNA-143 and miRNA-145 expression could be a predictive indicator for obese T2DM cases, decreased status of vitamin-D was also significantly associated with impaired fasting blood sugar and HDL level, therefore it is important to evaluate the vitamin-D status among T2DM cases for better clinical outcome during the intervention.

Vitamin D status in children and its association with glucose metabolism in northern China: a combination of a cross-sectional and retrospective study

OBJECTIVES

This study aimed to explore the vitamin D status of children in northern China and the association between vitamin D and glucose metabolism.

DESIGN

Cross-sectional study was conducted among child participants and retrospective study designs were conducted among adult participants.

SETTING AND PARTICIPANTS

Both studies were recruited from Harbin, 326 children were included in children's study, 8469 adults were included in adult study.

PRIMARY AND SECONDARY OUTCOME MEASURES

Physical examination, lifestyle and dietary habit data were recorded in all the participants. Serum insulin, glucose, 25(OH)D₃ concentrations in children and serum glucose and lipids levels in adults were measured. Rickets history was also investigated in adults, which was used to define vitamin D deficiency in childhood. The associations were tested by linear regression and binary logistic regression.

RESULT

In the children's study, only 10.7% of participants were vitamin D sufficient (≥30 ng/mL). Inverse correlations between serum 25(OH)D₃ concentration and fasting insulin and homeostasis model assessment - insulin resistance (HOMA-IR) were found, and children with lower serum 25(OH)D₃ concentrations were likely to have insulin resistance (IR) (OR: 0.955, 95% CI: 0.917 to 0.995, p value: 0.027). In an adult study, rickets in childhood increased the risk of type 2 diabetes in male participants (OR=1.414, 95% CI=1.013 to 1.972; p value=0.042), but this result was not observed in female participants.

CONCLUSION

Our findings suggest that vitamin D deficiency is widespread in northern China. Vitamin D deficiency in childhood was associated with IR and increased the risk of type 2 diabetes in male adults.

Normalization of Vitamin D Serum Levels in Patients with Type Two Diabetes Mellitus Reduces Levels of Branched Chain Amino Acids

Background and Objectives: Vitamin D is involved in pancreatic beta-cell function, insulin sensitivity, and inflammation. Further, elevation in branched-chain amino acids (BCAAs) has been implicated in type 2 diabetes (T2DM) pathology. However, the relationship between vitamin D and BCAAs in T2DM remains unclear. The current study aimed to investigate the relationship between vitamin D and BCAAs in T2DM. Materials and Methods: In total, 230 participants (137 with T2DM and 93 healthy controls) were recruited in a cross-sectional study. Furthermore, an additional follow-up study was performed, including 20 T2DM patients with vitamin D deficiency. These patients were prescribed weekly vitamin D tablets (50,000 IU) for three months. The levels of several biochemical parameters were examined at the end of the vitamin D supplementation. Results: The results showed that patients with T2DM had higher serum levels of BCAAs and lower serum levels of 25-hydroxyvitamin D (25(OH)D) compared with those of the healthy controls (p < 0.01). The serum levels of vitamin D were negatively correlated with BCAA levels in T2DM patients (r = −0.1731, p < 0.05). In the follow-up study, 25(OH)D levels were significantly improved (p < 0.001) following vitamin D supplementation. Vitamin D supplementation significantly reduced the levels of BCAAs, HbA1c, total cholesterol, triglycerides, and fasting glucose (p < 0.01). Conclusion: Overall, these results suggest a role for BCAAs and vitamin D in the etiology and progression of T2DM. Thus, managing vitamin D deficiency in patients with T2DM may improve glycemic control and lower BCAA levels.

Associations of Serum Total 25OHD, 25OHD3, and epi-25OHD3 with Insulin Resistance: Cross-Sectional Analysis of the National Health and Nutrition Examination Survey, 2011–2016

Background: Vitamin D may have a role in insulin sensitivity. However, the data on the association between various metabolites of Vitamin D and insulin-related parameters have been limited. Methods: We identified 6026 adults aged 20–80 years who participated in the 2011–2016 National Health and Nutrition Examination Survey (NHANES). Serum total 25OHD, 25OHD3, and epi-25OHD3, fasting glucose, insulin, and HOMA2-IR were obtained from the NHANES data. The association between serum Vitamin D-related values and insulin resistance was analyzed using a generalized linear model. For risk analysis, multifactorial logistic regression was used. Results: The median total 25-hydroxyvitamin D level, 25-hydroxyvitamin D3 level, and 3-epi-25-hydroxyvitamin D3 level were 62.5 nmol/L, 58.8 nmol/L, and 3.3 nmol/L, respectively. After adjustment for sex, age, race, ethnicity, and education status, the ORs for the insulin resistance of participants of total 25-hydroxyvitamin D, 25-hydroxyvitamin D3, and 3-epi-25-hydroxyvitamin D3 were 0.32 (95% CI 0.24, 0.43), 0.34 (95% CI 0.26, 0.44), and 0.64 (95% CI 0.53, 0.77), respectively. After an adjustment for body mass index, diabetes, and drinking and smoking, the ORs for the insulin resistance of the participants for total 25-hydroxyvitamin D, 25-hydroxyvitamin D3, and 3-epi-25-hydroxyvitamin D3 were 0.56 (95% CI 0.40, 0.78), 0.63 (95% CI 0.46, 0.85), and 0.99 (95% CI 0.80, 1.24), respectively. Conclusions: Our study provides suggestive evidence for the association between Vitamin D concentrations and a lower risk of insulin resistance. Evidence from larger and more adequately powered cohort studies is needed to confirm our results.

Consistent Inverse Associations of Total, “Bioavailable”, Free, and “Non-Bioavailable” Vitamin D with Incidence of Diabetes among Older Adults with Lower Baseline HbA1c (≤6%) Levels

Background: Serum 25-hydroxyvitamin (25(OH)D) levels are inversely associated with risk of diabetes. The “free hormone hypothesis” suggests potential effects to be mainly related to concentrations of “bioavailable” and free rather than total 25(OH)D. We assessed associations of serum concentrations of vitamin D-binding protein (VDBP), as well as total “bioavailable”, complementary “non-bioavailable”, and free 25(OH)D, with the risk of developing diabetes among non-diabetic older adults in a large population-based cohort study in Germany. Methods: We included 4841 non-diabetic older adults aged 50–75 years at the baseline exam from the ESTHER cohort conducted in Saarland, Germany, in 2001–2002. Concentrations of “bioavailable” and free 25(OH)D were derived from serum concentrations of VDBP, total 25(OH)D, and albumin. Incidence of diabetes was ascertained during up to 14 years of follow-up. Associations were quantified by multivariable Cox proportional hazards regression models with comprehensive confounder adjustment. Results: During a median follow-up of 10.6 years, 837 non-diabetic participants developed diabetes. We observed similar inverse associations with developing diabetes for VDBP (hazard ratio (HR) for lowest versus highest quintile: 1.37, 95% confidence interval (CI): 1.09, 1.72), total 25(OH)D (HR: 1.31, 95% CI: 1.03, 1.66), and “non-bioavailable” 25(OH)D (HR: 1.30, 95% CI: 1.02, 1.65). Associations were smaller and statistically insignificant for “bioavailable” and free 25(OH)D. However, associations of total “non-bioavailable”, “bioavailable”, and free 25(OH)D with incidence of diabetes were much stronger among, and essentially restricted to, participants with lower baseline HbA_1c (≤6%) levels. Conclusions: This large prospective cohort study of older Caucasian adults, in agreement with results from randomized trials and Mendelian randomization studies, supports a protective effect of vitamin D against development of diabetes. The “free hormone theory” may not be relevant in this context. However, our results underline the importance of adequate vitamin D status among those who have not yet shown any sign of impaired glucose tolerance.

Associations between serum vitamin D3, atherogenic indices of plasma and cardiometabolic biomarkers among patients with diabetes in the KERCADR study

BACKGROUND

We sought the association between serum 25-hydroxyvitamin D₃ (25(OH) D₃) levels and atherogenic indices of plasma as novel predictive biomarkers of cardiometabolic disease risk in patients with type 2 diabetes mellitus (T2DM).

METHODS

The present study was a nested case-control study conducted on 252 participants with T2DM and controls from the second phase of the KERCADR cohort study. The participants with a mean (±SD) age of 49.79 ± 5.85 years were randomly selected and allocated into case and control groups. Independent t-test, Hierarchical Linear Regression, Univariate ANOVA, and partial correlation were used for analysis the data. Atherogenic indices of plasma include Castelli Risk Index I (CRI I), Castelli Risk Index II (CRI II), and the novel Atherogenic Index of Plasma (AIP), and Atherogenic Coefficient (AC).

RESULTS

There was a significant difference among case and control groups for AIP in males and females (P < 0.001 and P = 0.007, respectively). The levels of AIP, CRI I, and AC significantly decreased (P = 0.017, P = 0.029, and P = 0.029, respectively) with improved serum vitamin D status only in control male participants. The main effect of BMI and vitamin D status on AIP, CRI I, and AC, and the main effect of BMI on CRI I, CRI II, and AC were significant in control males and females, respectively.

CONCLUSION

We conclude that there is a reverse significant association between AIP and serum vitamin D among healthy males. Low serum level of vitamin D is associated with atherogenic dyslipidemia. Therefore, improving vitamin D status as an important indicator may alleviate AIP as a surrogate marker for predicting the risk of CVD events in healthy men and women with normal BMI.

Vitamin D Intake and Factors Associated With Self-Reported Vitamin D Deficiency Among US Adults: A 2021 Cross-Sectional Study

Vitamin D deficiency is a global issue that may be attributed to various factors such as dietary habits, sun exposure, age, race and chronic conditions. The purpose of this study was to determine the relationship between vitamin D intake from food/supplements and factors that may be associated with self-reported vitamin D deficiency among US adults. A cross-sectional online study was conducted among 1,637 adults using a 38-item questionnaire. Frequency counts and percentages were tabulated and a multiple linear regression was performed. Statistical significance was determined at p &lt; 0.05. Participants (n = 554, 33.8%) were considered vitamin D deficient and consumed an average of 347.05 ± 307.8 IUs of vitamin D through foods/beverages. The multivariate linear regression showed no statistically significant difference with vitamin D intake from foods/beverages on vitamin D deficiency status. Significant positive correlations were seen with vitamin D deficiency status and certain chronic conditions such as chronic kidney disease (p = 0.04), depression (p &lt; 0.001), diabetes (p = 0.02), and vitamin D supplement use (p &lt; 0.001). Significant negative correlations were observed with vitamin D deficiency status and age (p = 0.01) and sun exposure (p &lt; 0.001). Future focus should be on educating individuals about factors associated with vitamin D to reduce the prevalence of vitamin D deficiency.

Hormonal and metabolic profiles of obese and nonobese type 2 diabetes patients: implications of plasma insulin, ghrelin, and vitamin D levels

Type 2 diabetes (T2D) is associated with obesity whereas loss of weight is a feature of the disease; however, the two states are not mutually exclusive. Obesity is linked with changes in hormonal activity and overall body metabolism.

MATERIALS AND METHODS

In this study, 408 T2D patients were recruited in three distinct studies conducted in Bahrain, Saudi Arabia, and Kuwait in three different intervals between 2001 and 2019. In addition to demographics, glycemic and lipid profiles were obtained in all studies, whereas plasma insulin and HOMA-IR, vitamin D, and ghrelin were analyzed in Saudi Arabia. Different techniques such as chemical auto-analyzer, ELISA, chemiluminescent immunoassay, radioimmunoassay were used.

RESULTS

The obese (BMI ≥ 30 kg/m2) compared with nonobese (BMI 18.5 to <30) patients with diabetes were more likely to be women (P < 0.001), smaller in age (P = 0.028), and with shorter disease duration (P = 0.018). Unexpectedly, the glycemic and lipid profiles were consistently comparable between the two groups in the three sites. Furthermore, vitamin D was strikingly lower in obese patients with diabetes (P = 0.007). Finally, plasma ghrelin (P = 0.163), insulin (P = 0.063), and HOMA-IR (P = 0.166) were comparable between obese and nonobese patients with diabetes.

CONCLUSION

Diabetic obesity was significantly associated with female sex, young age, short disease duration, and noticeably low vitamin D, and a trend of high insulin levels. However, the obese and nonobese patients had comparable metabolic profiles with no differences in insulin resistance and ghrelin levels. Further studies, especially at a molecular level, are needed to explore this topic which is barely investigated.

Effect of Vitamin D Supplementation on Glycemic Control in Prediabetes: A Meta-Analysis

Clinical research results of vitamin D supplementation in the improvement of prediabetes remain controversial. Accordingly, a literature search was conducted of PubMed, Embase (Ovid), and Web of Science prior to 9 November 2021. Randomized controlled studies reported that the following indicators were included: body mass index (BMI), fasting blood glucose (FBG), 2 h oral glucose tolerance test plasma glucose (2h-PG), hemoglobin A1c (HbA1c), insulin resistance by homeostasis model assessment (HOMA-IR), homeostasis model assessment of β-cell function (HOMA-B), and fasting insulin (FINS). Twenty-nine articles (N = 3792) were included in the present meta-analysis. Intriguingly, vitamin D supplementation resulted in a vast improvement in FBG (standardized mean difference (SMD) = -0.38; 95%CI: -0.59, -0.16), HbA1c (SMD = -0.14; 95%CI: -0.22, -0.06) and FINS (SMD = 0.18; 95%CI: -0.26, -0.09), but not in other outcomes. However, preferred changes were observed in subgroups, as follows: Asia (SMD_2h-PG = -0.25, 95%CI: -0.45, -0.04), study duration ≥1 year (SMD_HOMA-IR = -0.44, 95%CI: -0.81, -0.06) (SMD_HOMA-B = 0.34, 95%CI: 0.01, 0.66), baseline 25(OH)D < 50 nmol/L (SMD_2h-PG = -0.23, 95%CI: -0.39, -0.06), and baseline 25(OH)D ≥ 50 nmol/L (SMD_HOMA-IR = -0.50, 95%CI: -0.96, -0.03). In conclusion, oral supplementation of vitamin D has shown better effects in improving FBG, HbA1c, and FINS compared with controls among prediabetics; long-term vitamin D supplementation could have additional effects in participants with vitamin D deficiency for 2h-PG, HOMA-IR, and HOMA-B.

Sex-Specific Effects of Vitamin D Status on the Metabolic Profile in Prediabetic Subjects

INTRODUCTION

We aim to investigate the effect of vitamin D on metabolic parameters in a population with prediabetes and to detect possible sex differences.

METHODS

In 621 patients with diagnosed prediabetes, glucose, lipid, and anthropometric parameters were measured. Furthermore, the interaction of 25-OH-vitamin D (25-hydroxyvitamin D) with metabolic and glucose metabolism parameters was analysed in the total prediabetic population, as well as after stratification by sex (female vs. male prediabetic subgroup), by logistic regression.

RESULTS

25-OH-vitamin D was negatively related to cholesterol, BMI, fatty liver index, insulin, and HOMA-IR. Especially in the male prediabetic cohort, 25-OH-vitamin D levels negatively correlated with total cholesterol levels (r = -0.17, p=0.001), with triglycerides (r = -0.17, p=0.001), and with HbA1c levels (r = -0.14, p=0.010). Only in the female cohort with prediabetes, we found a negative correlation of 25-OH-vitamin D levels with systolic (r = -0.18, p=0.005) and diastolic blood pressures (r = -0.23, p < 0.001).

CONCLUSION

In this study, in females with prediabetes, 25-OH-vitamin D was notably related to a more favourable metabolic profile, including lower total cholesterol and higher HDL cholesterol levels. On the contrary, in men with prediabetes, there was a stronger association between 25-OH-vitamin D and cholesterol-HDL quotient, as well as fatty liver index was observed in the male prediabetic subgroup. Therefore, sex differences should be considered in future studies on vitamin D and glucose tolerance status.

Diagnostic significance of serum lncRNA HOTAIR and its predictive value for the development of chronic complications in patients with type 2 diabetes mellitus

BACKGROUND

Type 2 diabetes mellitus (T2DM) affects the social economy and quality of life, and has become a major threat to human health. This observation aimed to study the possibility of serum HOTAIR as a diagnostic index in patients with T2DM and to explore the prognostic potential of HOTAIR in the development of T2DM.

METHODS

The expression of HOTAIR in serum of 96 patients with T2DM and 82 healthy controls was detected by the qRT-PCR technique. The related biochemical indexes of all participants were determined, such as total cholesterol (TC) and fasting blood glucose (FBG). The value of serum HOTAIR in the diagnosis of T2DM in the two groups was analyzed by the ROC curve. Moreover, the prognostic value of HOTAIR on T2DM was examined by the K-M curve and COX multivariate analysis.

RESULTS

The results of the qRT-PCR analysis showed that the serum level of HOTAIR in patients with T2DM was significantly higher than that in healthy controls. ROC analysis showed that HOTAIR in serum was a diagnostic factor of T2DM. Further multivariate analysis showed that HOTAIR could be an independent biomarker in the prediction of chronic complications for T2DM patients, such as diabetic retinopathy and diabetic nephropathy.

CONCLUSIONS

We found the augment of HOTAIR expression was a character of T2DM. The high expression of serum HOTAIR was a potential non-invasive diagnostic marker and independent prognostic factor in patients with T2DM.

A high prevalence of prediabetes and vitamin D deficiency are more closely associated in women: results of a cross-sectional study

OBJECTIVE

Many studies have shown that vitamin D deficiency is associated with insulin resistance and metabolic syndrome. However, few studies have shown independent associations between vitamin D deficiency and the metabolic characteristics of prediabetes. We aimed to evaluate the relationship between serum vitamin D concentration and metabolic risk factors in adults with prediabetes.

METHODS

We enrolled 161 patients aged 25 to 75 years in a cross-sectional study and collected clinical and biochemical data, including 25-hydroxyvitamin D (25[OH]D) status and fasting glucose concentration. Vitamin D status was defined as follows: deficiency (25[OH]D <49.9 ng/mL), insufficiency (49.9 to 74.9 nmol/L) or sufficiency (>74.9 nmol/L). Prediabetes was defined using fasting plasma glucose concentrations of 5.55 to 6.49 mmol/L.

RESULTS

The prevalences of vitamin D deficiency and insufficiency were 49.7% and 24.8%, respectively. Participants with vitamin D deficiency had a higher prevalence of prediabetes than those without (53.8% vs. 32.1%), and there was a significant relationship between female sex and vitamin D status (odds ratio: 1.382; 95% confidence interval: 0.335-5.693).

CONCLUSION

Vitamin D deficiency is more closely associated with a high prevalence of prediabetes in women than in men. Further studies are needed to elucidate the explanation for this association.

Serum vitamin D levels in relation to type-2 diabetes and prediabetes in adults: a systematic review and dose-response meta-analysis of epidemiologic studies

BACKGROUND

Findings of observational studies that investigated the relationship between vitamin D deficiency and abnormal glucose homeostasis were contradictory. This meta-analysis of epidemiologic studies evaluated the association of vitamin D status and risk of type-2 diabetes (T2D) and prediabetes in adults.

METHODS

A systematic search was conducted on all published articles in five electronic databases (including MEDLINE/PubMed, EMBASE, Institute for Scientific Information, Scopus and Google scholar), up to August 2020. Twenty-eight prospective cohort and nested case-control studies and 83 cross-sectional and case-control investigations that reported relative risks (RRs) or odds ratios (ORs) with 95% confidence intervals (CIs) for abnormal glucose homeostasis in relation to serum vitamin D levels in adults were included in the analysis.

RESULTS

In prospective studies, high versus low level of vitamin D was respectively associated with significant 35%, 30% and 51% decrease in risk of T2D (RR:0.65; 95%CI: 0.55-0.76; 27 effect sizes), combined T2D and pre-diabetes (RR:0.70; 95%CI: 0.52-0.95; 9 effect sizes) and pre-diabetes (RR:0.49; 95%CI: 0.26-0.93; 2 effect sizes). These inverse associations were significant in almost all subgroups. Dose-response analysis in prospective studies showed that each 10 ng/ml increase in serum vitamin D levels resulted in 12% and 11% reduced risk of T2D (RR:0.88; 95%CI: 0.83-0.94) and combined T2D and prediabetes (RR:0.89; 95%CI: 0.87-0.92), respectively. In cross-sectional and case-control studies, highest versus lowest level of serum vitamin D was linked to reduced odds of T2D (OR:0.64; 95%CI: 0.57-0.72; 42 effect sizes) and combined T2D and pre-diabetes (OR:0.79; 95%CI: 0.74-0.85; 59 effect sizes); but not pre-diabetes (OR:0.64; 95%CI: 0.17-2.37; 11 effect sizes).

CONCLUSION

This meta-analysis of epidemiologic studies disclosed that serum vitamin D level was reversely associated with the risk of T2D and combined T2D and prediabetes in adults, in a dose-response manner. However, the association was not remarkable for pre-diabetes.

Association of serum vitamin D levels with chronic disease and mortality

Introduction

Introduction: whether hypovitaminosis D is an overarching cause of increased mortality or a prognostic marker of poor health has not been well elucidated. Objectives: we sought to determine the association of serum 25-hydroxyvitamin D [25-(OH)-D3] levels with the clinical biochemical parameters and mortality risk in chronic diseases. Methods: we reviewed the clinical charts and collected the clinical biochemical parameters of patients diagnosed with chronic conditions who had at least one 25-(OH)-D3 determination, with or without calcium and vitamin D supplementation, and who were selected using a cluster random sampling design (n = 1,705). The analysis was focused on metabolic disorders (type-2 diabetes mellitus [T2DM] and obesity), autoimmune disorders, and mortality. Multivariate logistic regression analyses were performed. Results: low 25-(OH)-D3 levels were reported in 1,433 (84.0%) patients, of which 774 (45.4%) had insufficiency (20-29 ng/mL) and 659 (38.6%) patients had deficiency (< 20 ng/mL). Lower 25-(OH)-D3 levels in T2DM patients were associated with higher glycosylated hemoglobin levels (p < 0.001). Patients with 25-(OH)-D3 levels < 12.5 ng/mL had a higher mortality risk than those with levels ≥ 12.5 ng/mL (HR: 3.339; 95% CI: 1.342-8.308). We observed lower 25-(OH)-D3 levels in patients with grade-III obesity (p = 0.01). We found a higher risk of 25-(OH)-D3 deficiency in rheumatoid arthritis, type-1 diabetes, and systemic lupus erythematosus (p = 0.032, p = 0.002, p = 0.049, respectively). Conclusions: we found a significant relationship between 25-(OH)-D3 levels and glycemic control, body mass index, autoimmune disease, and mortality risk. Nevertheless, whether hypovitaminosis D plays a causal role or is a consequence of chronic disease remains controversial.

The role of systemic inflammation in the association between serum 25-hydroxyvitamin D and type 2 diabetes mellitus

BACKGROUND & AIMS

The association between serum 25-hydroxyvitamin D [25(OH)D] and type 2 diabetes mellitus (T2DM) remains inconclusive. Moreover, whether inflammatory biomarkers are involved in this association has not been explored. This study aims to investigate serum 25(OH)D in relation to T2DM in a Chinese population and provide clues for the inflammatory mechanism whereby serum 25(OH)D deficiency increases T2DM risk.

METHODS

A cross-sectional study of 47,803 participants aged 18-96 years was performed in a health management center in 2017. Multivariate linear or logistic regression models and mediation analysis were used to examine the relationships between serum 25(OH)D, inflammatory biomarkers (white blood cell counts and mean platelet volume), and T2DM.

RESULTS

Of the 47,803 participants included, 5.2% were diabetic and 51.4% were serum 25(OH)D deficient. The study revealed a significant inverse association between serum 25(OH)D and T2DM risk after adjustment for potential confounders (P for trend = 0.002); the multivariate-adjusted odds ratios (ORs) and 95% confidence intervals (CIs) across serum 25(OH)D levels (sufficiency, insufficiency, and deficiency) were 1.00 (reference), 1.17 (1.03-1.33), and 1.25 (1.09-1.43), respectively. This study also showed a significant indirect effect of serum 25(OH)D on T2DM risk through total white blood cell count, neutrophil count, lymphocyte count, and monocyte count (P values < 0.05); the proportions mediated were 9.89%, 7.51%, 2.94%, and 2.82%, respectively.

CONCLUSIONS

Serum 25(OH)D deficiency was independently associated with an elevated risk of T2DM in a Chinese adult population and low-grade systemic inflammation might be one of its biological mechanisms.

Vitamin D and iodine status was associated with the risk and complication of type 2 diabetes mellitus in China

The purpose of this study was to assess the relationship between 25-hydroxyvitamin D (25(OH)D), urinary iodine concentration (UIC), and type 2 diabetes mellitus (T2DM) risk and complications and to establish a model to predict T2DM in the general population. A total of 567 adults (389 T2DM patients and 178 controls) were enrolled, and the levels of 25(OH)D, iodine, and blood biochemical parameters were measured. Pearson’s correlation analysis showed an inverse correlation between 25(OH)D level, UIC, and T2DM risk. Low 25(OH)D level was a risk factor for developing T2DM (OR, 0.81; 95% CI, 1.90–2.63; P = 0.043) after adjustment for multiple risk factors. 25(OH)D level and UIC were inversely correlated with short-term and long-term glucose levels. 25(OH)D deficiency was also associated with a high incidence of T2DM complicated with thyroid dysfunction. A prediction model based on 25(OH)D, iodine status, and other risk factors was established and recommended to screen high-risk T2DM in the general population and provide early screening and timely treatment for them.

The role of vitamin D in prevention of type 2 diabetes. A meta-analysis

BACKGROUND AND AIMS

Recently, there are evidences that have shown vitamin D homeostasis has an impact in the development of type 2 diabetes. However, still it is unclear if vitamin D supplementation reduces the risk of overt diabetes. This meta-analysis of cross-sectional studies and RCTs was conducted to evaluate the role of vitamin D in prevention of type 2 diabetes and to elucidate this controversial topic.

METHODS

A systematic search for English-language literature was done via PUBMED/Medline and Google Scholar up to March 2020. Based on a fixed and random effects model, the OR, HR and 95% CI were used to evaluate the combined risk. This study followed Preferred Reporting Items for Systematic Reviews and Meta-analysis (PRISMA) Guidelines.

RESULTS

After eligibility assessment 10 studies with a total of 34,882 participants were included in meta-analysis. Meta-analysis of cross-sectional studies suggested that there was a statistically significant association between the vitamin D and type 2 Diabetes; the pooled OR (95%CI) was 1.77 [1.51, 2.07] (P < 0.001). Meta-analysis of RCTs have shown that there was no statistically significant association between vitamin D supplementation and prevention of type 2 Diabetes, the pooled HR (95%CI) was 0.89 [0.77, 1.02] (P = 0.08).

CONCLUSION

In conclusion, this meta-analysis suggests that there is association between the vitamin D and type 2 diabetes. However, the result of RCTs suggests emphasis of future studies for genetic factors such as polymorphic variants of the VDR gene as one factor in this complex process.

Serum Vitamin D Affected Type 2 Diabetes though Altering Lipid Profile and Modified the Effects of Testosterone on Diabetes Status

Numerous studies have investigated the associations between serum vitamin D or testosterone and diabetes; however, inconsistencies are observed. Whether there is an interaction between vitamin D and testosterone and whether the lipid profile (total cholesterol (TC), triglyceride (TG), high-density lipoprotein cholesterol (HDL-C), and low-density lipoprotein cholesterol (LDL-C)) mediates the association between vitamin D and diabetes is unclear. To investigate the effect of vitamin D and testosterone on impaired fasting glucose (IFG) or type 2 diabetes mellitus (T2DM), 2659 participants from the Henan Rural Cohort were included in the case-control study. Generalized linear models were utilized to estimate associations of vitamin D with IFG or T2DM and interactive effects of vitamin D and testosterone on IFG or T2DM. Principal component analysis (PCA) and mediation analysis were used to estimate whether the lipid profile mediated the association of vitamin D with IFG or T2DM. Serum 25(OH)D3, 25(OH)D2, and total 25(OH)D levels were negatively correlated with IFG (odds ratios (ORs) (95% confidence intervals (CIs)): 0.99 (0.97, 1.00), 0.85 (0.82, 0.88), and 0.97 (0.96, 0.98), respectively). Similarity results for associations between serum 25(OH)D2 and total 25(OH)D with T2DM (ORs (95%CIs): 0.84 (0.81, 0.88) and 0.97 (0.96, 0.99)) were observed, whereas serum 25(OH)D3 was negatively correlated to T2DM only in the quartile 2 (Q2) and Q3 groups (both p < 0.05). The lipid profile, mainly TC and TG, partly mediated the relationship between 25(OH)D2 or total 25(OH)D and IFG or T2DM and the proportion explained was from 2.74 to 17.46%. Furthermore, interactive effects of serum 25(OH)D2, total 25(OH)D, and testosterone on T2DM were observed in females (both p for interactive <0.05), implying that the positive association between serum testosterone and T2DM was vanished when 25(OH)D2 was higher than 10.04 ng/mL or total 25(OH)D was higher than 40.04 ng/mL. Therefore, ensuring adequate vitamin D levels could reduce the prevalence of IFG and T2DM, especially in females with high levels of testosterone.

Relationship between serum zinc, HOMA2 parameters and glycemic status in a regional Australian hospital population

BACKGROUND: Previous studies demonstrated lower serum zinc among prediabetics and diabetics, compared to normoglycemics, however no current data is available for regional Australia. OBJECTIVE: We aimed to determine the relationship between serum zinc, glycemic status and Homeostasis Model Assessment (HOMA2) parameters in a regional Australian hospital population. METHODS: Retrospective review of patients presenting to a regional Australian hospital between June-2004 and April-2017 was conducted. Patients ordered for fasting blood glucose (FBG)+serum zinc; or FBG+serum insulin; or FBG+serum zinc+serum insulin were included. Serum zinc, FBG, serum insulin, lipid profile, vitamin-D and demographic information were collected. β-cell function, insulin resistance and insulin sensitivity were calculated by HOMA2 calculator. RESULTS: Three hundred and thirteen patient records were retrieved: 75% normoglycemic, 19% prediabetic, 6% diabetic. Serum zinc was lowest in diabetics and lower in prediabetics than normoglycemics. In simple linear regression among all participants, higher serum zinc associated with increased insulin sensitivity, decreased insulin resistance and decreased β-cell function. CONCLUSIONS: The low serum zinc status exhibited in diabetic and prediabetic individuals may play a role in insulin resistance pathogenesis. Higher zinc levels associated with greater insulin sensitivity and lower insulin resistance signifying the importance of investigating zinc supplementation in prediabetics to prevent or delay diabetes in future studies.

Association of Vitamin D with the TaqI Polymorphism of the VDR Gene in Older Women Attending the Basic Health Unit of the Federal District, DF (Brazil)

Aging is accompanied by various functional modifications determined by their environment, lifestyle, nutrition, and genetics. Based on these factors, it is essential to verify the vitamin deficiency in the elderly population. Hypovitaminosis D is commonly present in human aging, increasing the chances of developing noncommunicable chronic diseases. The VDR gene TaqI polymorphism may modify the vitamin D metabolic pathway by altering the interaction between the vitamin D receptor and the active circulating vitamin D. Therefore, this study aimed to investigate the association between serum vitamin D and biochemical and genetic factors, considering the TaqI polymorphism of the VDR gene, in an elderly population of the Federal District. The study was a descriptive, case-control, quantitative, and cross-sectional type and was conducted in two basic health units in the administrative region of Ceilândia, Federal District, DF, Brazil, with women aged 60 years or older. Anthropometric, biochemical, and genetic parameters (VDR TaqI polymorphism) were evaluated. The adopted significance level was 5%, and statistical analyses were performed using the SPSS version 20.0 program. The study consisted of 128 participants. The most prevalent age was from 60 to 65 years (N = 53; 41.4%). 66 elderly (51.6%) were part of the case group (hypovitaminosis D), while 62 were in the control group. In the case group, 30.2% had grade I obesity, 77.3% were hypertensive, and 51.5% were diabetic. The TT genotype was present in 47% of the case group and 54.8% in the control group (p=0.667). There was no association between serum vitamin D levels and the VDR gene variant TaqI polymorphism in an elderly Brazilian population.

Association between vitamin D and prediabetes: A PRISMA-compliant meta-analysis

BACKGROUND

Previous studies showed conflicting results for associations between vitamin D and prediabetes. The study aimed to make a systematic review and meta-analysis for the association between vitamin D and prediabetes.

METHODS

We searched for articles identifying associations between vitamin D and prediabetes published in English until July 2019 in following databases (PubMed, Web of Science, EMBASE, Medline, Google Scholar, and Cochrane databases). Finally, we conducted these analyses (heterogeneities examination, meta-regression analyses, sensitivity analysis, and publication bias examination) using STATA 12.0 software (Stata Corporation, College Station, TX, USA). Q test and I were applied to examine heterogeneities between studies.

RESULTS

Twelve studies were finally included in the present study. The study included 4 studies to explore the association between serum levels of 25-hydroxy (OH) vitamin D and risks of prediabetes (including 3094 participants). Additionally, the present study included 8 studies (including 865 individuals with prediabetes treated with vitamin D supplementation and 715 patients treated with placebo) to assess differences in therapeutic effects between individuals with prediabetes treated with vitamin D supplementation and those treated with placebo. The present study showed no significant associations between low serum levels of 25(OH) vitamin D and high risk of prediabetes. Additionally, the study showed no significant differences in changes of hemoglobin A1c (HbA1c), fasting plasma glucose (FPG), and homeostatic model assessment of insulin resistance (HOMA-IR) between individuals with prediabetes treated with vitamin D and those patients given placebo, whereas meta-analysis showed significantly greater changes in 2-hour oral glucose tolerance test (2HPG) in individuals with prediabetes treated with vitamin D, compared with individuals with prediabetes treated with placebo.

CONCLUSION

The study supported that low serum levels of 25(OH) vitamin D increased the risk of prediabetes. In addition, vitamin D supplementation improves impaired glucose tolerance in prediabetes. However, more large-scale clinical trials are essential to explore the association between vitamin D and prediabetes.

Vitamin D binding protein is related to cardiac autonomic function and metabolic status in prediabetes

A putative causal relationship between vitamin D status and glucose metabolism and a direct effect of vitamin D on cardiac autonomic function (CAF) have been suggested. We hypothesized that vitamin D binding protein (DBP), as a transporter of vitamin D, might also influence CAF and the overall metabolic risk. The present study aims to assess the relationship between DBP and CAF and metabolic status in a high-risk population with prediabetes. A total of 174 subjects (mean age 49.1±12.9 years, mean body mass index 30.2±6.2 kg/m²) were divided into 2 groups according to glucose tolerance: 48 with normal glucose tolerance and 126 with prediabetes. Glucose tolerance was assessed during oral glucose tolerance test, applying 2006 World Health Organization criteria. Fasting and postload glucose and immunoreactive insulin were measured (homeostatic model assessment of insulin resistance and homeostatic model assessment of β-cell function were calculated). Anthropometric indexes, blood pressure, hemoglobin A1c, creatinine, lipids, high-sensitivity C-reactive protein, total 25-hydroxyvitamin D, DBP (free 25-hydroxyvitamin D was calculated), and intact parathormone were measured. Body composition was estimated by impedance analysis (InBody 720), whereas tissue advanced glycation end products were assessed by skin autofluorescence (AGE Reader, DiagnOptics, the Netherlands). CAF was evaluated by АNX-3.0 system, applying standard autonomic tests. DBP was found to be elevated in women, as well as in the presence of cardiac autonomic dysfunction and metabolic syndrome. DBP was related to parasympathetic activity in both sexes and in prediabetes; to body fat in women and in prediabetes; and to age and high-density lipoprotein cholesterol in men. Vitamin D deficiency was established in 40.8% of the studied cohort. These results support the hypothesis that DBP is associated with CAF and some metabolic parameters in prediabetes.

Reduced Serum Vitamin D Levels Are Associated with Insulin Resistance in Patients with Obstructive Sleep Apnea Syndrome

Background and objectives: Obstructive sleep apnea syndrome (OSAS) is associated with cardiovascular and metabolic risk factors, such as insulin resistance. Furthermore, OSAS has been associated with decreased levels of vitamin D (Vit D). The aim of the study was to assess the association between Vit D levels (expressed as 25(OH)D serum levels) and insulin resistance in patients with OSAS. Materials and Methods: Serum 25(OH)D levels were measured in consecutive subjects who had undergone polysomnography and pulmonary function testing. OSAS patients were divided into those with (homeostatic model assessment [HOMA-IR] ≥ 2) and without insulin resistance (HOMA-IR < 2). Results: Overall, 92 patients (81 males) were included in the study. OSAS patients with insulin resistance significantly differed from those without insulin resistance in terms of the body-mass index (BMI) (36.3 ± 5.8 compared to 32 ± 5.6 kg/m², respectively, p = 0.001), apnoea-hypopnoea index (AHI) (57.4 ± 28.9 compared to 40.9 ± 27.9 events/h, respectively, p = 0.009) and indices of hypoxia during sleep. Patients with OSAS and insulin resistance had lower levels of serum 25 (OH) D compared with OSAS but without insulin resistance (19.3 ± 11.5 vs 26.7 ± 12.2 ng/mL, respectively, p = 0.005). Regression analysis demonstrated a negative association of 25(OH)D levels (β = −0.048, odds ratio [OR]: 0.953, 95% confidence interval [CI]: 0.913–0.995, p = 0.030) and a positive association of BMI (β = 0.110, OR: 1.116, 95% CI: 1.007–1.237, p = 0.036) with insulin resistance. Conclusions: Vit D insufficiency was significantly more frequent among OSAS patients with insulin resistance. Both low 25(OH)D levels and high BMI were associated with the risk of insulin resistance in this population.

Serum vitamin D status in type 2 diabetic patients from Gaza Strip

OBJECTIVE

To assess serum vitamin D status and its relations to other biochemical parameters in type 2 diabetic patients from Gaza Strip.

MATERIALS AND METHODS

This case-control study included 58 type 2 diabetic patients as well as 58 non-diabetic controls. Patients and controls were matched for age and gender. Data were obtained from questionnaire interview, and biochemical analysis of blood samples.

RESULTS

Serum vitamin D was significantly lower in diabetic patients compared to non-diabetic controls (25.9 ± 11.0 versus 34.6 ± 13.8 ng/dl, % difference = 28.8%, P < 0.001). The number of patients having vitamin D deficient, insufficient and sufficient were 6 (10.4%), 35 (60.3%) and 17 (29.3%) compared to controls of 3 (5.2%), 16 (27.6%) and 39 (67.2%), respectively (χ² = 14.672, P < 0.001). Serum glucose, glycated hemoglobin (HbA1c), serum alanine aminotransferase (ALT), aspartate aminotransferase (AST) and triglycerides were significantly higher in patients than in controls whereas serum insulin, high density lipoprotein cholesterol (HDL-C) and calcium were significantly lower in patients. Serum vitamin D showed significant negative correlations with HbA1c (r = - 0.186, P = 0.046), ALT (r = - 192, P = 0.040) and AST (r = - 0.188, P = 0.044) whereas significant positive correlations were found with HDL-C (r = 0.188, P = 0.044) and calcium (r = 0.239, P = 0.010).

CONCLUSION

The significant negative and positive correlations of vitamin D with HbA1c and calcium, respectively suggests that vitamin D supplementation would be of potential therapeutic value in clinical settings for controlling of type 2 diabetes and more importantly its complications. However, a well-designed clinical trials are needed to define the contribution of vitamin D status and therapy in the global diabetes problem.

Vitamin D and cardiometabolic disorders: a review of current evidence, genetic determinants and pathomechanisms

Vitamin D deficiency has been implicated in the pathophysiology of cardiometabolic disorders including obesity, type 2 diabetes mellitus, cardiovascular diseases and polycystic ovary syndrome. Despite a large number of experimental and observational studies supporting a role for vitamin D in these pathologies, randomized controlled trials have reported little to no effect of vitamin D supplementation in the prevention or treatment of these disorders, although some results remain ambiguous. Polymorphisms in genes related to vitamin D metabolism, particularly in the vitamin D receptor and binding protein and the metabolizing enzyme 1-α-hydroxylase, have emerged as potential contributors to these divergent results. It is now becoming increasingly recognized that the effects and potential benefits of vitamin D supplementation may vary by several factors including vitamin D deficiency status, ethnicity and/or the presence of genetic variants, which affect individual responses to supplementation. However, these factors have seldom been explored in the available literature. Future trials should consider inter-individual differences and, in particular, should aim to clarify whether certain subgroups of individuals may benefit from vitamin D supplementation in the context of cardiometabolic health.

Effects of Consuming Calcium-Rich Foods on the Incidence of Type 2 Diabetes Mellitus

The effect of calcium consumption in the prevention of type 2 diabetes mellitus (T2DM) remains controversial, and depends on food calcium sources. This prospective study aimed to evaluate the association between calcium-rich food consumption and T2DM incidence among Korean adults. We analyzed the data of 8574 adults aged 40⁻69 years, without a history of T2DM, cardiovascular disease, and cancer at the baseline from the Korean Genome and Epidemiology Study. The consumption of calcium-rich foods was assessed using a validated semi-quantitative food frequency questionnaire. T2DM-related data were collected using biennial questionnaires, health examinations, and clinical tests. Hazard ratios (HRs) and 95% confidence intervals (CIs) were calculated using Cox proportional hazards regression models. In the multivariate-adjusted model, yogurt intake was inversely associated with T2DM risk (HR: 0.73; 95% CI: 0.61⁻0.88 in the fourth quartile as compared to the first quartile). However, the intakes of other calcium-rich foods, including milk and anchovies, were not significantly associated with T2DM risk. Yogurt may provide protective effects against T2DM in Korean adults, owing to the beneficial effects of probiotics. Further prospective large-scale cohort studies should be conducted to validate these findings.