Vitamin D in gestational diabetes: a broadened frontier

Maternal Serum 25-Hydroxyvitamin D as a Possible Modulator of Fetal Adiposity: A Prospective Longitudinal Study

25-hydroxyvitamin D (25(OH)D) regulates lipid metabolism, and its decrease is proposed as a pathogenesis of metabolic syndrome, gestational diabetes mellitus (GDM), and eventually fetal adiposity. Decreased 25(OH)D is also linked with the development of gestational diabetes mellitus (GDM), which is associated with increased fetal adiposity. Fetuses are dependent on the supply of 25(OH)D from maternal circulation. However, the influence of maternal serum 25(OH)D on fetal adiposity remains unclear. This study aimed to investigate the association between maternal serum 25(OH)D and fetal adiposity. A prospective longitudinal study was conducted in a cohort of 89 (including 21 GDM) singleton pregnancies. Maternal blood samples were obtained at 10, 24, 30, and 36 weeks, and fetal ultrasonography was performed at 24, 30, and 36 weeks of gestation. Estimated fetal adiposity (EFA) was calculated as the average z-score of cross-sectional arm and thigh percentage fat area and anterior abdominal wall thickness as previously reported. The multiple linear regression analyses indicated that maternal 25(OH)D levels across gestation were not associated with EFA at 24 and 30 weeks, while maternal 25(OH)D at 24 weeks was inversely correlated with EFA at 36 weeks. Particularly, in the GDM group, maternal 25(OH)D levels at 10, 24, 30, and 36 weeks all showed a significant negative correlation with EFA at 36 weeks. Decreased maternal serum 25(OH)D level could be an early biomarker of increased fetal adiposity in late gestation, especially in diabetic pregnancies.

Causal association between vitamin D and gestational diabetes mellitus: a two-sample Mendelian randomization study

BACKGROUND

Previous articles on the relationship between vitamin D and gestational diabetes mellitus (GDM) were inconsistent. Their relationship has been observed primarily through observational studies, and the causality of this association has not been established.

METHODS

A two-sample Mendelian randomization (MR) research was conducted to test the causal association between vitamin D and GDM, utilizing publically available statistics from genome-wide association studies (GWAS). This study obtained genetic variants from GWAS including vitamin D (N = 373,045,10,783,672 Single Nucleotide Polymorphisms SNPs), and GDM (5687 cases and 117,892 controls). The major technique was the inverse variance weighted approach (IVW), although there were other approaches as well, such as MR-Egger regression, weighted median, weighted mode, and simple mode. Additionally, we conducted sensitivity analyses to detect any potential diversity and horizontal pleiotropy.

RESULTS

The study suggested that there was no causal link between vitamin D and GDM (all methods p > 0.05). For heterogeneity, MR egger Q value was 113.7, p < 0.05; IVW Q value was 114.7, p < 0.05. Therefore, random- effects IVW approach was applied. Regarding pleiotropy, the MR Egger regression intercept was 0.0046, which was close to zero with a p value of 0.452, suggesting the absence of pleiotropy.

CONCLUSIONS

We observed no assosiation between genetically predicted vitamin D and the risk of GDM, implying that insufficient vitamin D may do not confer an increased susceptibility to GDM.

Effects of MTHFR C677T polymorphism on homocysteine and vitamin D in women with polycystic ovary syndrome

OBJECTIVES

To evaluate the correlation between serum vitamin D, homocysteine and the methylene tetrahydrofolate reductase (MTHFR) C677T polymorphism in women with polycystic ovary syndrome (PCOS). Study design We retrospectively compared the serum homocysteine and vitamin D levels and the MTHFR C677T polymorphism in 104 PCOS patients and 104 controls. Parameters related to PCOS were statistically analysed.

RESULTS

Comparative analysis revealed that women with PCOS had significantly greater serum homocysteine levels (P = 0.002) and lower vitamin D concentrations (P = 0.040) than controls. The distribution frequency of the MTHFR C677T genotype did not significantly differ between the PCOS group and the control group. (P > 0.05). In the PCOS group, the serum level of homocysteine in the TT group was significantly greater than that in the CT (P = 0.003) and CC (P = 0.002) groups and the level of vitamin D in the TT group was significantly less than that in the CC (P < 0.001) and CT (P = 0.172) groups. The results were similar when the PCOS and control groups were divided according to whether they had insulin resistance. Vitamin D levels were significantly negatively correlated with homocysteine levels in all PCOS patients (r = -0.281, P = 0.004), similarly, vitamin D levels were negatively correlated with homocysteine levels in the CC, CT and TT of PCOS patients. According to multivariate analysis, vitamin D concentration was an independent risk factor for hyperhomocysteinaemia (adjusted OR 1.372, 95 % CI: 1.100-1.712).

CONCLUSIONS

No significant differences were found in the distributions of MTHFR C677T genotypes between the PCOS and control groups but these genotypes affected the patients' serum homocysteine and vitamin D concentrations. Women with the TT genotype have significantly lower vitamin D levels and higher homocysteine levels than women with the CC and CT genotypes. However, because of the limitations of this investigation, large-sample, high-quality prospective studies are needed to further verify these results in the future.

25-Hydroxyvitamin D, Vitamin D Binding Protein and Gestational Diabetes Mellitus: A Two-Sample Mendelian Randomization Study

BACKGROUND

Numerous studies have examined whether vitamin D is associated with gestational diabetes mellitus (GDM). Nevertheless, it is still challenging to determine the causality, due to a number of shortcomings in observational research and randomized controlled trials.

OBJECTIVE

Mendelian randomization (MR) with two samples was conducted to investigate the potential causative association between 25-hydroxyvitamin D (25(OH)D), vitamin D binding protein (VDBP) and GDM risk.

METHODS

Publicly accessible summary data from independent cohorts were used for two-sample MR. For 25(OH)D, we obtained data from UK Biobank, IEU and EBI, then performed a meta-analysis to enhance the statistical power (via METAL); for VDBP, data were obtained from the INTERVAL study; for GDM, data were obtained from FinnGen. The inverse variance weighted (IVW) approach was performed as the main analysis, together with several sensitivity analyses, such as MR-Egger, maximum likelihood, weighted median, and weighted mode.

RESULTS

The IVW results revealed a weak negative causal connection between 25(OH)D and GDM risk [OR (95% CI) = 0.71 (0.50, 0.99), p = 0.046]. However, the causal association was unstable according to sensitivity analyses, and Cochran's Q test revealed significant heterogeneity. After removing BMI-related IVs, the causal association between 25(OH)D and GDM disappeared [OR (95% CI) = 0.76 (0.55, 1.06), p = 0.101]. In addition, our study found no proof to support the assumption that VDBP level was related to GDM risk causally [OR (95% CI) = 0.98 (0.93, 1.03), p = 0.408].

CONCLUSIONS

According to this study, a weak negative causal association between 25(OH)D and GDM risk was found, while we had little proof to support the link between VDBP and GDM. To further explore whether total or free 25(OH)D levels and GDM are causally related, GWAS data with an emphasis on women of reproductive age and other ethnic groups are required.

Effects of vitamin D supplementation on glucose and lipid metabolism in patients with type 2 diabetes mellitus and risk factors for insulin resistance

BACKGROUND

Type 2 diabetes mellitus (T2DM) is a chronic metabolic disease featured by insulin resistance (IR) and decreased insulin secretion. Currently, vitamin D deficiency is found in most patients with T2DM, but the relationship between vitamin D and IR in T2DM patients requires further investigation.

AIM

To explore the risk factors of IR and the effects of vitamin D supplementation on glucose and lipid metabolism in patients with T2DM.

METHODS

Clinical data of 162 T2DM patients treated in First Affiliated Hospital of Harbin Medical University between January 2019 and February 2022 were retrospectively analyzed. Based on the diagnostic criteria of IR, the patients were divided into a resistance group (n = 100) and a non-resistance group (n = 62). Subsequently, patients in the resistance group were subdivided to a conventional group (n = 44) or a joint group (n = 56) according to the treatment regimens. Logistic regression was carried out to analyze the risk factors of IR in T2DM patients. The changes in glucose and lipid metabolism indexes in T2DM patients with vitamin D deficiency were evaluated after the treatment.

RESULTS

Notable differences were observed in age and body mass index (BMI) between the resistance group and the non-resistance group (both P < 0.05). The resistance group exhibited a lower 25-hydroxyvitamin D3 (25(OH)D3) level, as well as notably higher levels of 2-h postprandial blood glucose (2hPG), fasting blood glucose (FBG), and glycosylated hemoglobin (HbA1c) than the non-resistance group (all P < 0.0001). Additionally, the resistance group demonstrated a higher triglyceride (TG) level but a lower high-density lipoprotein-cholesterol (HDL-C) level than the non-resistance group (all P < 0.0001). The BMI, TG, HDL-C, 25(OH)D3, 2hPG, and HbA1c were found to be risk factors of IR. Moreover, the post-treatment changes in levels of 25(OH)D3, 2hPG, FBG and HbA1c, as well as TG, total cholesterol, and HDL-C in the joint group were more significant than those in the conventional group (all P < 0.05).

CONCLUSION

Patients with IR exhibit significant abnormalities in glucose and lipid metabolism parameters compared to the non-insulin resistant group. Logistic regression analysis revealed that 25(OH)D3 is an independent risk factor influencing IR. Supplementation of vitamin D has been shown to improve glucose and lipid metabolism in patients with IR and T2DM.

Nutritional Assessment of the Symptomatic Patient on a Plant-Based Diet: Seven Key Questions

Plant-based diets, both vegan and vegetarian, which emphasize grains, vegetables, fruits, legumes, nuts, and seeds are increasingly popular for health as well as financial, ethical, and religious reasons. The medical literature clearly demonstrates that whole food plant-based diets can be both nutritionally sufficient and medically beneficial. However, any person on an intentionally restrictive, but poorly-designed diet may predispose themselves to clinically-relevant nutritional deficiencies. For persons on a poorly-designed plant-based diet, deficiencies are possible in both macronutrients (protein, essential fatty acids) and micronutrients (vitamin B12, iron, calcium, zinc, and vitamin D). Practitioner evaluation of symptomatic patients on a plant-based diet requires special consideration of seven key nutrient concerns for plant-based diets. This article translates these concerns into seven practical questions that all practitioners can introduce into their patient assessments and clinical reasoning. Ideally, persons on plant-based diets should be able to answer these seven questions. Each serves as a heuristic prompt for both clinician and patient attentiveness to a complete diet. As such, these seven questions support increased patient nutrition knowledge and practitioner capacity to counsel, refer, and appropriately focus clinical resources.

Vitamin D Fortification and Its Effect on Athletes' Physical Improvement: A Mini Review

Poor vitamin D status is a widespread problem regardless of age and sex, emphasizing the necessity of new food sources to improve vitamin D levels. Currently, approximately 60% of dietary vitamin D consumption occurs via fortified foods. Vitamin D insufficiency (50-90%) is widespread according to age and region, despite different levels of sunlight exposure. The food industry must identify more effective strategies to increase normal dietary vitamin D intake and improve overall health. Strategies for vitamin D fortification include bioaddition, wherein a vitamin D-rich food source is added to staple foods during processes. These bioadditive strategies expand the range of vitamin D-containing foods and appeal to different preferences, cultures, and economic statuses. In several countries, vitamin D deficiency places athletes at a high risk of disease susceptibility. Due to low sun exposure, athletes in countries with higher and lower levels of sunlight have similar risks of vitamin D deficiency. In this review, we summarize recent technical advances to promote vitamin D utilization by humans during sports activities and in relation to the normal practices of athletes.

Insulin Requirement for Gestational Diabetes Control Is Related to Higher Vitamin D Levels up to 1 Year Postpartum: A Prospective Cohort Study

Vitamin D deficiency is highly prevalent in pregnant women and has been related to a higher risk of gestational diabetes mellitus (GDM). The aim of this study is to analyze vitamin D status evolution in a population of pregnant women with and without GDM. Two-hundred women were included from January 2019 to February 2022 as follows: Control group -CG-, Lifestyle group -LG- (GDM not requiring insulin), and Insulin group -IG- (GDM requiring insulin). Visits were carried out at baseline, antenatal, postpartum, and 1 year after birth. Vitamin D levels, weight, and insulin resistance were measured at every visit. Data about the season, vitamin D supplementation, Mediterranean diet adherence, and physical activity were included. In the three groups, 134 women were included in the CG, 43 in the LG, and 23 in the IG. Vitamin D levels were similar among the groups at baseline, but they were significantly higher in the LG and IG in comparison with the CG at the antenatal visit and significantly higher in the IG vs. CG and LG at the postpartum and 1 year after birth visits. Vitamin D levels were independently related to vitamin D supplementation and the season at baseline, to the season and belonging to the LG or IG at the antenatal visit, and were only independently associated with belonging to the IG at postpartum and 1 year after birth visits. In conclusion, in our population, women with GDM requiring insulin had higher levels of vitamin D in comparison with those not requiring insulin and healthy controls at postpartum and 1 year after pregnancy. Requiring insulin during pregnancy seems to be a factor that independently determines the levels of vitamin D until 1 year after birth. More studies are required to reproduce these data in other populations and to elucidate the mechanisms underlying these findings.