The Effects Of Vitamin D Supplementation On Vitamin D Deficient Patients With Type 2 Diabetes

Objective:In this study,we investigated the relationship between vitamin D deficiency and metabolic syndrome in patients with type 2 diabetes through a cross-sectional study and the effects of vitamin D₃ supplementation in patients with type 2 diabetes with a serum25 hydroxyvitamin D[25?OH?D]level less than 20 ng/mL through a community intervention trail.Besides,we explored the protective mechanism of 1,25dihydroxyvitamin D₃[1,25?OH?₂D₃]on the damage of human umbilical vein endothelial cells?HUVECs?cultured by high glucose.Methods:1).The relationship between vitamin D level and metabolic indicators in patients with type 2 diabetes was analyzed by a cross-sectional study using multivariable logistic regression analysis and restricted cubic spline with a data collecting on demographic indexes,body measurement indexes and serologic examination of all the enrolled 270subjects.2).The effects of vitamin D₃ supplementation in patients with type 2 diabetes with a serum 25?OH?D level less than 20 ng/m L were analyzed by a community intervention trail.After a 800 IU/d vitamin D₃ supplementation on 100 subjects,we observed the change of serum 25?OH?D levels,other serological and metabolic indicators in order to demonstrate its influence.3).The protective mechanism of 1,25?OH?₂D₃ on the damage of HUVECs was explored by testing cell vitality,oxidative stress indexes and structural function.The HUVECs were cultured by high concentration of glucose combined application of1,25?OH?₂D₃ at the level of 1 nmol/L.Results:1).270 patients with type 2 diabetes were enrolled.The percentages of vitamin D deficiency and insufficiency were 43.71%and 39.63%,respectively.Serum 25?OH?D concentrations were inversely related to the prevalence of metabolic syndrome.The restricted cubic spline showed that the odds ratio?OR?of metabolic syndrome in the 14ng/mL was 2.12 compared with the reference?30 ng/m L?.The risk of metabolic syndrome reduced significantly only when the serum 25?OH?D level was more than 30ng/mL.2).100 diabetic patients with a serum 25?OH?D level less than 20 ng/m L were enrolled.The levels of serum 25?OH?D in the subjects could gradually be enhanced by a800 IU/d vitamin D₃ supplementation?14.15±4.13,17.01±6.50,29.22±8.48 and38.80±9.47 ng/mL?.It could also improve the sugar metabolic abnormalities and increase the serum N-osteocalcin level,especially for the elderly women patients.3).The experimental results showed that the high glucose could inhibit cell proliferation and stimulate oxidative stress response along with the higher MDA formation and lower SOD formation.And 1,25?OH?₂D₃ could significantly reduce the MDA formation and increase the SOD and GSH levels.Immunofluorescence and protein detection showed that high glucose environment will increase the permeability of HUVECs.It also affected the structure of the tight junction between cells.However,1,25?OH?₂D₃ significantly increased the vitamin D receptor?VDR?and myosin light chain?MLC?protein and improved the permeability by regulating the migration of intracellular Ca²⁺and reshaping the cell structure and tight junction between cells,as well as promoting the synthesis and release of NO.Conclusions:1).The serum 25?OH?D concentrations were inversely related to the prevalence of metabolic syndrome in the patients with type 2 diabetes and the risk of the metabolic syndrome increased significantly when the serum 25?OH?D level was less than 14ng/mL.2).The levels of serum 25?OH?D in the subjects could gradually be enhanced by a800 IU/d vitamin D₃ supplementation.It could also improve the sugar metabolic abnormalities and increase the serum N-osteocalcin level,especially for the elderly women patients.3).1,25?OH?₂D₃ could reduce the endothelial cell injury and apoptosis caused by the high glucose environment by inhibiting oxidative stress response and improving endothelial cell permeability.