Role of phytochemicals in the management of metabolic syndrome

Introduction Low vitamin D status has been found to be associated with impaired glycemic control in patients who suffer from type 2 diabetes; however, whether vitamin D supplementation is associated with improved glycemic status remains controversial The aim of this study was to summarize evidence from randomized controlled trials (RCTs) to assess the efficacy of vitamin D supplementation in reducing glycosylated haemoglobinA1c (HbA1c) and fasting blood glucose (FBG) levels Materials/Methods We searched PubMed, Web of Science and the Cochrane Library for reports published up to March 2017 We selected parallel RCTs investigating the effect of vitamin D or vitamin D analogues on HbA1c or FBG levels in type 2 diabetes patients Cohen's d was calculated to represent the standardized mean difference (SMD) for each study, and the SMDs with 95%confidence intervals (CIs) were pooled using a random effects model Results Twenty-four studies were included that evaluated HbA1c levels and 18 studies were included that evaluated FBG levels Meta-analyses showed that vitamin D supplementation was associated with reduced HbA1c levels (standardized mean difference (SMD) − 025 [− 045 to − 005]) but had no influence on FBG levels (SMD − 014 [− 031 to 003]) However, the subgroup analyses suggested that vitamin D supplementation was associated with reduced HbA1c levels (SMD − 039 [− 067 to − 010]) and FBG (SMD − 027 [− 046 to − 007]) among patients with 25-hydroxyvitamin D (25(OH) D) deficiency at baseline Significantly reduced HbA1c levels were also observed in association with vitamin D supplementation in the subgroup including type 2 diabetes patients with a body mass index (BMI) Conclusions Vitamin D supplementation could be effective at improving glycemic control in vitamin D deficient or non-obese type 2 diabetes patients

Vitamin D supplementation and glycemic control in type 2 diabetes patients: A systematic review and meta-analysis.

Is inflammatory signaling involved in disease-related muscle wasting? Evidence from osteoarthritis, chronic obstructive pulmonary disease and type II diabetes.

Objective. To investigate the effect of single nucleotide polymorphisms (SNPs) of the key genes in vitamin D metabolic pathway on the serum 25(OH)D level after long-term vitamin D3 supplementation and provide a theoretical basis for rational vitamin D3 supplementation in diabetic patients with different genetic backgrounds. Methods. Patients with type 2 diabetes (T2DM) who met the inclusive criteria were given 800 IU of vitamin D3 daily for 30 consecutive months. Serum 25(OH)D levels was measured at enrollment and every 6 months after enrollment. The average value of four-time measurements represented individual serum 25(OH)D level during vitamin D3 supplementation. Multiplex TaqMan genotyping was used to determine the distribution of eight candidate SNPs in genes of DHCR7, CYP2R1, CYP27B1, CYP24A1, and VDR, which are key genes in the vitamin D metabolic pathway, in diabetic patients. Results. At baseline, the average serum 25(OH)D level was  ng/mL, and 17.9% of patients had a ≥30 ng/mL level. During supplementation, the level of 25(OH)D increased significantly at each time point, and the average 25(OH)D level increased to  ng/mL; however, there were 44.6% of patients whose serum 25(OH)D levels were still below 30 ng/mL. In the patients with CYP27B1 (rs10877012) G/T genotype, 71.79% achieved sufficient level of 25(OH)D, which was significantly higher than the other two genotypes ( ). Compared with those with T/T genotype, the RR of the patients with rs10877012 for ChiCTR-IPC-17012657 .

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The Association between Polymorphisms of Vitamin D Metabolic-Related Genes and Vitamin D3 Supplementation in Type 2 Diabetic Patients.

Vitamin D is essential for the maintenance of calcium and phosphorus homeostasis, skeletal growth and various other metabolic processes. The prevalence of vitamin D deficiency in India is 50-90% in various studies. Factors such as low sunlight exposure, age-related decrease in cutaneous synthesis, and low dietary intake of vitamin D contribute to the high prevalence of vitamin D inadequacy which has emerged as a highly pervasive condition. Bone diseases such as rickets in children, osteomalacia and osteoporosis in adults are related with vitamin D insufficiency. Literature evidences show that low vitamin D levels are also related with increased risk of falls, fractures, muscle pain, muscle weakness, cardiovascular risk, diabetes mellitus, polycystic ovary syndrome (PCOS), infections, and autoimmune disorders also. Adequate intake of vitamin D is necessary for all individuals of any age group. Sunlight exposure, food fortification and routine supplementation can only fulfill the deficiency of vitamin D. This review article emphasizes on the prevalence of vitamin D deficiency, potential implications, and effect of supplementation on cardiovascular disease, diabetes mellitus, polycystic ovary syndrome (PCOS), autoimmune disorders, sleep disturbance and pain. In addition, the present review discusses the screening, treatment, and prevention strategies for vitamin D deficiency.

Treatment of Vitamin D Deficiency and Comorbidities: A Review

Objective
To explore the effects of oral vitamin D supplementation on anthropometric parameters and insulin resistance (IR) in type 2 diabetes mellitus (T2DM).


Methods
A total of 164 subjects with T2DM, aged 30-75 years, were randomly divided into two groups of intervention and control. The intervention group received a daily dose of 0.50 μg calcitriol while the control group maintained the original treatment regimen. At the beginning and end of 12-week supplementation trial, the demographic and anthropometric data were recorded and the serum levels of glucose, insulin, HbA1C and 25(OH)D measured. IR was assessed by the homeostasis model approximation index.


Results
There was no significant inter-group difference at baseline. Compared with the baseline level, body mass index(BMI)((-0.7±1.7) vs (-0.4±1.4) kg/m2)(P 30 ng/ml group ((5±3)vs (4±3))(P<0.05). And BMI ((26±6) vs (26±4) kg/m2)(P<0.05), WC ((84±11) vs (82±12) cm) (P<0.05), FPG ((8±4) vs (6±4)mmol/L)(P<0.05), FPI ((17±4) vs (16±4)μU/ml)(P<0.05)and HbA1C((7.4±0.9)% vs(7.0±1.2)%)(P<0.05)decreased statistically significant only in 15-20 ng/ml group. Multivariate regression analysis showed that HOMA-IR was a significant independent risk factor for 25 (OH) D (OR=13, 95%CI=4-39, P<0.05).


Conclusion
There are significant improvements in BMI, WC, FPG, FPI, HbA1C and HOMA-IR after supplementation.Thus vitamin D supplementation may reduce insulin resistance in T2DM.


Key words: 
Type 2 diabetes; Insulin resistance; Vitamin D

Yinyin Li

Papers

Effects of vitamin D supplementation on insulin resistance in patients with type 2 diabetes mellitus