Effect of serum 25-hydroxyvitamin D3 on insulin resistance and β-cell function in newly diagnosed type 2 diabetes patients

Seasonal and sex-related variation in vitamin D status and its association with other biochemical markers in young individuals: A cross-sectional study

BACKGROUND

While several studies have investigated the association between vitamin D deficiency and biochemical parameters, the results are still inconsistent and mostly overlook seasonal variations. This study explored the relationships between 25-hydroxy-vitamin D (25(OH)D) concentrations, biochemical markers, and seasonal variation among young males and females.

METHODS

A cross-sectional study was conducted among 203 individuals aged 18-24 years of both sexes residing in Brasilia, Brazil (latitude: 15°S). Sociodemographic variables, season of blood collection, and serum levels of 25(OH)D, total cholesterol, HDL-cholesterol, LDL-cholesterol, triglycerides, glycated hemoglobin (HbA1c), glucose, insulin, hs-CRP, parathyroid hormone, ionized calcium, and alkaline phosphatase were included. Descriptive statistics and differences among groups, correlations, and linear regression tests were performed.

RESULTS

The mean age of the participants was 21.17±1.7 years, and the mean serum 25(OH)D level was 25.76±7.0 ng/mL. Of the participants, 50.7% had vitamin D insufficiency (20 to 29.9 ng/mL), and 23.2% were vitamin D deficient (≤20 ng/mL). Vitamin D deficiency was higher in the spring (53.2%) and among females (29.5%). In young men with vitamin D insufficiency/deficiency (≤29.9 ng/mL) (n = 49), 25(OH)D levels were inversely correlated with HOMA-β (r = -0.234, p = 0.032) and triglyceride (r = -0.415, p = 0.003) levels. However, there were no significant correlations between 25(OH)D concentrations and biochemical markers among women with insufficient and deficient vitamin D levels.

CONCLUSION

This study found a high prevalence of vitamin D insufficiency/deficiency among young individuals living in Brasília, Brazil, particularly women and during the spring season. Our findings suggest that lower 25(OH)D levels (≤29.9 ng/mL) may be associated with insulin resistance and an increased risk of cardiovascular disease in young men studied. However, further studies with larger representative samples are needed to explore the mechanisms underlying the association between vitamin D and biochemical parameters.

Differences in daily milk production during early pregnancy alter placental characteristics and neonatal metabolic amino acid levels in dairy cows

We investigated the effects of differences in milk production during early pregnancy on placental characteristics at full term, calf birth weights, and their metabolic status. Thirty-four Holstein cows were categorized into three groups (Low, n = 9; Middle, n = 16; High, n = 9) based on the quartile of average daily 4% fat-corrected milk production during early pregnancy. The High group showed higher milk component production than the other groups (P < 0.05) during early and mid-pregnancy. Although most placental characteristics did not differ significantly among the groups, cows in the High group had larger individual cotyledons and fewer medium-sized cotyledons than those in the Low group (P < 0.05). Plasma amino acid concentrations of calves in the Low and High groups were significantly higher than those of calves in the Middle group, although calf birth weights were similar among the groups. Furthermore, cows in the Low group had longer dry periods than those in the High (P = 0.004) and Middle (P = 0.058) groups. This suggests that cows in the Low group may have provided more amino acids to the fetus because of low lactation and long dry periods. Conversely, cows in the High group required more energy for lactation during early pregnancy, which can reduce nutrient availability to the placenta and fetus; however, increasing individual cotyledonary sizes during late pregnancy may ensure that the same amounts of amino acids as those in cows in the Low group are supplied to the fetus, recovering the birth weights.

Serum and supplemental vitamin D levels and insulin resistance in T2DM populations: a meta-analysis and systematic review

Observational studies have shown a negative correlation between Vitamin D level and the likelihood of developing insulin resistance (IR) and/or diabetes over time, yet evidence remains inconsistent. In this meta-analysis and systematic review, we strive to define the potential association between serum or supplemental Vitamin D Levels and insulin resistance respectively, as well as the contribution of Vitamin D to type 2 diabetes, and to summarize the biologic plausibility of Vitamin D. Four databases (PubMed, Embase, Cochrane Library, and Web of Science) were searched for this Systematic Literature Review (SLR) to find appropriate observational studies and clinical trials published in English through to July 2022. EndNote (version X9) is used to manage the literature search results. We calculated Standard Mean Differences (SMDs) and Risk Ratios (RRs) with their 95% Confidence Intervals (CIs), separately, for continuous and dichotomous outcomes. The correlation coefficients were normalized to z values through Fisher's z-transformation to calculate the relevant statistics. Meta-analyses were carried out for all comparisons, based on a random-effects pooling model. Data analysis was performed using RevMan (version 5.3) and STATA (version 15.1). All statistical tests were two-sided, with P < 0.05 were regarded as significant. In our current meta-analysis, there are 18 RCTs and 20 observational studies including 1243 and 11,063 participants respectively. In the overall analysis, the diabetic with Vitamin D supplement treatment group showed significantly improve serum insulin (SMD =  - 0.265, 95% CI - 0.394 to - 0.136, P < 0.05), glucose (SMD =  - 0.17, 95% CI - 0.301to - 0.039, P < 0.05) and HOMA-IR (SMD =  - 0.441, 95% CI - 0.582 to - 0.3, P < 0.05) compared with the routine treatment group. Correlation analysis results showed that all three outcomes were significantly correlated in a negative manner with raised Vitamin D (insulin: r =  - 0.08 95% =  - 0.12 to - 0.04; glucose: r =  - 0.06 95% =  - 0.11 to - 0.01; HOMA-IR: r =  - 0.08 95% =  - 0.09 to - 0.06). Results of overall analysis proved that vitamin D has shown significant effect on regulates insulin resistance, and there is a significant inverse association between serum Vitamin D level and IR. Vitamin D supplementation is expected to be integrated into conventional medical approaches to prevent type 2 diabetes and to mitigate the burden of diabetes for individuals and society.PROSPERO registration number: CRD42022348295.

Association of urinary calcium and phosphorus excretion with renal disease progression in type 2 diabetes

OBJECTIVES

Diabetes is associated with a high incidence of microvascular disease, including nephropathy. The current study aimed to investigate the association of urinary calcium and phosphorus excretion with chronic kidney disease (CKD) progression in type 2 diabetes mellitus.

METHODS

A total of 159 T2DM patients with chronic kidney disease (CKD stage G1-G4) were retrospectively included. Patients were categorized into three groups according to the tertiles of 24-h urinary calcium and phosphorus excretion, respectively. Clinical parameters and laboratory findings were compared among the three groups. Cox proportional hazards models were used to estimate the associations of urinary calcium and phosphorus excretion with CKD progression and adjusted for baseline eGFR, urinary protein excretion, mean arterial pressure, and use of RAAS inhibitor. A cubic spline curve was used to explore the association between urinary calcium excretion and CKD progression, as well as urinary phosphorus excretion and CKD progression. Moreover, the subgroup effects of urinary calcium and phosphorus excretion on CKD progression were estimated using Cox regression. CKD progression was defined as double of baseline serum creatinine or occurrence of ESRD.

RESULTS

During a median of 18.23 months of follow-up, the composite renal outcomes were noted in 27%. Cumulative renal outcomes were significantly lower in the highest tertile of urinary calcium excretion and phosphorus excretion in Kaplan-Meier analyses. The multivariate Cox proportional hazards regression analyses indicated that both the highest tertile of urinary calcium and phosphorus excretion was associated with a lower risk for CKD progression compared with the lowest tertile. Restricted cubic spline analyses of the association between urinary calcium excretion and CKD progression indicated a linear association. Additionally, there was also a linear association between urinary phosphorus excretion and CKD progression. Subgroup analyses showed that higher urinary phosphorus excretion was particularly associated with a lower risk of CKD progression in non-diabetic kidney disease (NDKD) patients.

CONCLUSION

Higher urinary calcium and phosphorus excretion were associated with decreased risk of CKD progression in T2DM patients.

No Association between 25-Hydroxyvitamin D and Insulin Resistance or Thyroid Hormone Concentrations in a Romanian Observational Study

Background and objectives: Vitamin D is involved in insulin resistance through genomic and non-genomic mechanisms. Several observational and randomized studies have discrepant results; some of them showed an improved insulin resistance (IR), and others a neutral effect after vitamin D deficiency is corrected. Materials and Methods: We designed a retrospective observational study that included all women who presented for 33 months in an outpatient clinic in Bucharest, Romania. Results: We analyzed 353 patients with a mean age of 58.5 ± 13.7 years, a mean body mass index (BMI) of 27.36 ± 4.87 kg/m^-2, and a mean level of 25-hydroxyvitamin D (25OHD) of 39.53 ± 15.73 ng/mL. There were no differences in the calculated Homeostatic Model Assessment of Insulin Resistance variants 1 and 2 (HOMA-IR) and the Quantitative Insulin Sensitivity Check Index (QUICKI) between women with vitamin D deficit versus normal values. In multivariate analysis, there was no significant relation between 25OHD and the response variables considered by us. Conclusions: We observed a small positive correlation between a higher level of 25OHD and increased glycosylated hemolobin (HbA1c) or IR indices without clinical significance. Other modifiable or non-modifiable factors override 25OHD influence on IR in adult women with a normal serum level and may contribute to the remainder of the variability observed.

A double burden of tuberculosis and diabetes mellitus and the possible role of vitamin D deficiency

Tuberculosis remains a major global health challenge, particularly in low-to-middle income countries such as China. At the same time, the country is facing a rapidly increasing diabetes incidence over the last 10 years. Diabetes aggravates the tuberculosis epidemic which poses a serious challenge in public health. In recent years, the high prevalence of vitamin D deficiency represents a global health problem, which is also associated with the risk of diabetes, and tuberculosis. Therefore, this review aims to provide an overall and updated understanding of the epidemiology of co-occurrence of tuberculosis and diabetes in China, and to elucidate the possible role of vitamin D deficiency. In conclusion, significant aggravation of the tuberculosis epidemic due to diabetes may exist in China for a relatively long period of time to come. Further, the double burden and its implications to public health in this country may be significantly influenced by the high prevalence of vitamin D deficiency. Bidirectional screening for tuberculosis and diabetes is recommended, and extra vitamin D may benefit especially in a situation of a heavy tuberculosis burden combined with prevalent vitamin D deficiency. Longitudinal studies to verify the role of vitamin D deficiency in the double burden, and trials on the effect of vitamin D supplementation are needed in the future.

Association of increased renal Cyp24a1 gene expression with low plasma 1,25-dihydroxyvitamin D levels in rats with streptozotocin-induced diabetes

Decreases in plasma vitamin D concentrations have been reported in diabetes, although the mechanism involved in this decrease is unclear. Here, we investigated the association between Cyp24a1, a vitamin D catabolic enzyme, and abnormalities in vitamin D metabolism in streptozotocin-induced diabetes rats, an animal model of type 1 diabetes. Plasma 1,25-dihydroxyvitamin D [1,25(OH)₂D] levels were significantly lower in streptozotocin-induced diabetes rats and renal Cyp24a1 mRNA expression levels were increased. Western blotting analysis of streptozotocin-induced diabetes rats kidney tissues with anti-CYP24A1 antibody showed a strong signal around 40 kDa, which differs from the predicted 50–55 kDa molecular weight for full-length Cyp24a1 and could represent the Cyp24a1-splicing variant that lacks exons 1 and 2. We observed high levels of renal Cyp24a1-splicing variant mRNA expression in streptozotocin-induced diabetes rats. We also confirmed transcriptional up-regulation of endogenous Cyp24a1 mRNA expression through glucocorticoid receptors by glucocorticoid in opossum kidney proximal cells. Taken together, our results indicated that high Cyp24a1 expression levels may play a role in the decrease of plasma 1,25(OH)₂D levels in streptozotocin-induced diabetes rats. High plasma corticosterone levels in diabetes may affect transcriptional regulation to promote increases in Cyp24a1 expression.

Insulin resistance: Relationship between indices during late gestation in dairy cows and effects on newborn metabolism

To investigate the relationship between insulin resistance indices ["Revised quantitative insulin sensitivity check index" (RQUICKI; RQ), "Revised quantitative insulin sensitivity check index - β-hydroxybutyrate" (RQUICKI_BHB ; RQ_BHB ), and "Homeostasis model assessment-insulin resistance" (HOMA-IR; HR)], and metabolic parameters in dams during late gestation, and their newborn calves. Blood was sampled twice weekly during the experimental period in 30 dry Holstein cows. In calves, blood sampling and body weight measurements were performed immediately after birth, and in 1-week-old male calves, liver and muscle biopsy samples were obtained for determining metabolic factor mRNA levels. RQ and RQ_BHB were negatively correlated with insulin, nonesterified fatty acid, BHB, and albumin and were positively correlated with leptin levels in blood during late gestation (p < .05). RQ, rather than RQ_BHB , reflected metabolism of dams, while stronger positive correlations were present between HR and blood insulin concentrations than other parameters, and calves of dams with high HR had low body weight, and high liver and muscle expression of growth hormone and insulin receptor mRNA (p < .05). RQ and HR of dams during late gestation could serve as indicators of dam metabolism and predictors of metabolism in newborn calves respectively.

No association of 25-hydroxyvitamin D and parathormone levels with glucose homeostasis in type 2 diabetes - a study from Shillong, Meghalaya

Background: Although inadequate vitamin D and altered parathyroid hormone (PTH) are implicated in deranged glucose metabolism and risk of future diabetes, their role in regulating glucose homeostasis in established cases of diabetes is unclear. We aimed to (i) evaluate vitamin D status, and (ii) determine if vitamin D and PTH were associated with parameters of glucose homeostasis in type 2 diabetes (T2D) patients from Meghalaya, India. Methods: We determined 25-hydroxyvitamin D (25-OH-D) and PTH concentrations in 251 T2D patients (not on insulin), and examined their associations with the following parameters of glucose homeostasis: fasting blood sugar (FBS), post-prandial blood sugar (PPBS), glycated hemoglobin (HbA1c), fasting insulin (FI), homeostasis model assessments of insulin resistance (HOMA-IR) and β-cell function (HOMA-β). Results: None of the patients had adequate vitamin D (mean 25-OH-D = 19.3 ng/mL); 47.8% patients were deficient (25-OH-D < 20 ng/mL), while 52.2% were insufficient (25-OH-D < 30 ng/mL) vitamin D. Significant (P < 0.05) univariate associations were observed between: 25-OH-D and FI (r = 0.14); 25-OH-D and HOMA-β (r = 0.13); PTH and FI (r = -0.18), and PTH and HOMA-β (r = -0.11). However these associations disappeared after controlling for potential confounders. The 25-OH-D and PTH levels were not associated with any of the tested parameters of glucose homeostasis. Conclusion: There was widespread prevalence of vitamin D deficiency/insufficiency in our sample T2D patients. However, neither vitamin D nor PTH appeared to play a major role in influencing glucose homeostasis in this present selection of T2D cases.

Association of vitamin D deficiency with insulin resistance in middle-aged type 2 diabetics

BACKGROUND

Vitamin D deficiency contributes to the pathophysiology of insulin resistance (IR) and type 2 diabetes mellitus (T2DM). We investigated the association of 25-hydroxyvitamin D [25(OH)D] with IR and β-cell function in middle-aged participants.

METHODS

We enrolled 90 controls and 90 T2DM patients of both genders aged 30-50 years. Serum 25(OH)D, fasting plasma insulin (FPI), fasting plasma glucose (FPG), HbA1c, and lipid profile were measured by standard methods. Insulin resistance and sensitivity were assessed by triglyceride glucose (TyG) index, homeostatic model assessment (HOMA-IR), quantitative insulin sensitivity check index (QUICKI), and β-cell function by HOMA-B.

RESULTS

25(OH)D deficiency was reported as 40% in control and 70% in T2DM patients. 25(OH)D concentration was positively associated with age, blood pressure, T2DM duration, FPG, HbA1c, TyG index, and HOMA-IR and negatively associated with HOMA-B and QUICKI among all the participants (p ≤.001). Participants with severe 25(OH)D deficiency (<10 ng/ml) were 39 times higher odds of being T2DM, while, those with moderate deficiency (10-19ng/ml) and insufficiency (20-29 ng/ml) were 16 times and 13 times higher odds of being T2DM, respectively.

CONCLUSION

Sufficient 25(OH)D concentration may lower the risk of development of IR and T2DM in middle-aged control and diabetic participants.

Cardiometabolic healthy and unhealthy obesity: does vitamin D play a role?

OBJECTIVE

The aim of this observational study was to clarify the link between vitamin D status and metabolic syndrome (MetS) in people with visceral obesity.

DESIGN AND METHODS

One hundred ninety-six consecutive patients (152 women; mean age 51 ± 13 years) with visceral obesity (mean body weight 103 ± 20 kg, mean waist circumference (WC) 119 ± 13 cm) were enrolled at the Obesity Outpatient Clinic of the University of Insubria in Varese. Anthropometric measurements were recorded. Laboratory tests, including vitamin D (25(OH)D)), fasting blood glucose (FBG), lipid profile, liver and kidney function tests were assessed. Vitamin D status was defined according to the European Society of Endocrinology guidelines, MetS to the 2009 harmonized definition.

RESULTS

An inverse association emerged among 25(OH)D, body mass index (BMI) (P = 0.001) and WC (all P = 0.003). Serum 25(OH)D levels were inversely related to FBG and systolic blood pressure (SBP) (respectively, P = 0.01 and 0.02). Median serum 25(OH)D levels were 13.3 ng/mL (CI 95% 12; 15) in MetS and 16 ng/mL (CI 95% 14; 18) (P = 0.01) in non-MetS patients. Among patients with MetS, lower 25(OH)D concentrations were related to higher risk of hypertension (HT) (odds ratio (OR) 1.7, CI 95%, 0.7;4) and hyperglycemia (IFG)/type 2 diabetes (OR 5.5, CI 95% 2; 14).

CONCLUSION

Vitamin D status and MetS are inversely correlated in visceral obesity, particularly with regard to glucose homeostasis and BP. More extensive studies are required to investigate the potential for causality.

Derangement of calcium metabolism in diabetes mellitus: negative outcome from the synergy between impaired bone turnover and intestinal calcium absorption

Both types 1 and 2 diabetes mellitus (T1DM and T2DM) are associated with profound deterioration of calcium and bone metabolism, partly from impaired intestinal calcium absorption, leading to a reduction in calcium uptake into the body. T1DM is associated with low bone mineral density (BMD) and osteoporosis, whereas the skeletal changes in T2DM are variable, ranging from normal to increased and to decreased BMD. However, both types of DM eventually compromise bone quality through production of advanced glycation end products and misalignment of collagen fibrils (so-called matrix failure), thereby culminating in a reduction of bone strength. The underlying cellular mechanisms (cellular failure) are related to suppression of osteoblast-induced bone formation and bone calcium accretion, as well as to enhancement of osteoclast-induced bone resorption. Several other T2DM-related pathophysiological changes, e.g., osteoblast insulin resistance, impaired productions of osteogenic growth factors (particularly insulin-like growth factor 1 and bone morphogenetic proteins), overproduction of pro-inflammatory cytokines, hyperglycemia, and dyslipidemia, also aggravate diabetic osteopathy. In the kidney, DM and the resultant hyperglycemia lead to calciuresis and hypercalciuria in both humans and rodents. Furthermore, DM causes deranged functions of endocrine factors related to mineral metabolism, e.g., parathyroid hormone, 1,25-dihydroxyvitamin D3, and fibroblast growth factor-23. Despite the wealth of information regarding impaired bone remodeling in DM, the long-lasting effects of DM on calcium metabolism in young growing individuals, pregnant women, and neonates born to women with gestational DM have received scant attention, and their underlying mechanisms are almost unknown and worth exploring.

Vitamin D Metabolism and the Implications for Atherosclerosis

Vitamin D levels and metabolism may play a role in the pathogenesis and treatment of atherosclerosis and subsequent cardiovascular health. Herein, we discuss both normal and disordered vitamin D metabolism as it pertains to atherosclerosis, and we review major clinical trials regarding vitamin D levels and effects of supplementation. Although there are no official recommendations for vitamin D as it applies to atherosclerosis, it is clear that these two entities are linked. Further study of the complex association between vitamin D and atherosclerosis, as well as the effects of supplementation, are recommended.

Effect of serum 25-hydroxyvitamin D3 on insulin resistance and β-cell function in newly diagnosed type 2 diabetes patients

Aims/Introduction

To evaluate serum 25‐hydroxyvitamin D₃ (25(OH)D₃) in newly diagnosed type 2 diabetes patients and to explore the associations of 25(OH)D₃ with insulin resistance and β‐cell function.

Materials and Methods

A total of 97 newly diagnosed type 2 diabetes patients and 69 healthy controls were recruited. Serum 25(OH)D₃ was determined using high‐pressure liquid chromatography. Insulin resistance was measured using a homeostasis model assessment of insulin resistance (HOMA‐IR). β‐Cell function was determined using the HOMA β‐cell function index (HOMA‐β), early‐phase insulin secretion index (ΔI30/ΔG30) and area under the insulin curve (AUCins). Correlation analysis was carried out using Pearson's correlation and multiple stepwise regression analysis.

Results

Serum 25(OH)D₃ was much lower in patients with newly diagnosed type 2 diabetes (t = −13.00, P < 0.01), and the prevalence of hypovitaminosis 25(OH)D₃ was 62.9% (61/97) in diabetic patients. Among the diabetic patients, patients with hypovitaminosis 25(OH)D₃ showed higher glycosylated hemoglobin and AUCglu (P < 0.01) as well as lower HOMA‐β, ΔI30/ΔG30 and AUCins. Serum 25(OH)D₃ was independently positively correlated with ΔI30/ΔG30 and AUCins (P < 0.05), but was not significantly correlated with either HOMA‐IR or HOMA‐β. Only triglycerides, glycosylated hemoglobin and ΔI30/ΔG30 emerged as independent factors associated with serum 25(OH)D₃ in both diabetes patients and the health control group.

Conclusions

The present results further showed a low serum 25(OH)D₃ concentration in patients with newly diagnosed type 2 diabetes. 25(OH)D₃ deficiency is associated with disturbances in glucose metabolism and lipid metabolism. Serum 25(OH)D₃ is not correlated with basal insulin resistance or β‐cell function, but is significantly positively correlated with glucose‐stimulated insulin secretion and β‐cell function.