The Study On Relationship Between Serum 25-Hydroxyvitamin D₃ Concentration And Metabolic Syndrome

ObjectiveThe study to investigate the relationship between serum 25-hydroxyviamin D3 concentration [25(OH)D3] and metabolic syndrome (MS), and evaluate the 25-hydroxyviamin D3 level in Chinese population.Research design and methods1. Study object:The 105 outpatients with MS were selected who visited endocrine clinic of Qilu Hospital from November 2009 to January 2010, and all the patients were from Jinan of Shandong Province and its surrounding areas. The 102 health subjects were divided into control group, matched age, sex with MS group. The MS was defined according to the International Diabetes Federation (IDF) in 2005.2. Collecting the clinical data:A questionnaire was used to collect information such as age, sex, ethnicity, geographic location, education level, smoking, alcohol drinking, physical activity level in every week, self-reported the family history of diabetes, hypertension.All participants were invited to attend a physical examination, including weight, height, waist circumference, hip circumference, and blood pressure. After an overnight fast, peripheral venous blood samples were collected, including 25(OH)D3, plasma glucose, insulin, total cholesterol, triglycerides, HDL cholesterol, LDL cholesterol, uric acid.Waist-hip ratio(WHR) was calculated as waist circumference(cm)/hip circumference(cm).BMI was calculated as weight(kg)/height2 (m2).HOMA-IR was calculated as FINS (μIU/ml)×FPG (mmol/l)/22.5. 3. Data management of statistical analyses was done using the SPSS statistical Package (Version18.0). Continuous variables were presented as mean±standard deviation (±s), non-normal distribution of variables such as FPG, HOMA-IR, TG are on the logarithmic normalized after the analysis. Parameters between the two groups were used to compare two independent samples t test. Enumeration data was compared with chi-square test. Pearson correlation analysis and multiple linear stepwise regression were used to assess the association of 25(OH)D3 with the indexes of MS individual components. For all analysis, a p value less than 0.05 is considered to reach statistical significance.Results1. The mean concentration of 25(OH)D3 in the health subjects who from Jinan of Shandong Province and surrounding areas was 21.42±4.85ng/mL (95% confidence interval 20.46-22.37),20.04±4.68ng/mL (95% confidence interval 19.13-20.94)in the MS group, lower than the control group. The difference was statistically significant (P<0.05).2. Vitamin D nutritional status was assessed as "sufficiency" ((?)30ng/ml), "insufficiency" (20(?)25(OH)D3<30ng/ml), or "deficiency" (<20ng/ml)in the two groups. The percentages of 25(OH)D3 sufficiency, insufficiency and deficiency were 4%,57%,39% in the control group, and in the MS group were 3%,41%,56%, respectively.25 (OH) D3 deficiency in the patients with MS was significantly more prevalent than the control group (p<0.05).3. In the MS group, the male patients had significantly higher concentration of 25(OH)D3 than the female patients(21.32±4.60 ng/ml vs 18.52±4.36 ng/ml; p<0.05) 4. In the MS group, the concentration of 25(OH)D3 correlated negative with the waist circumference(r=-0.230,P<0.05), SBP(r=-0.303,P<0.01), FPG (r=-0.299,P<0.01), TG(r=-0.240,P<0.05), LDL-C(r=-0.330, P<0.01), and uric acid(r=-0.248,P<0.05). The concentration of 25(OH)D3 was correlated negative linear trend with BMI, WHR, DBP, FINS, HOMA-IR, TC, and correlated positive linear trend with HDL-C, but there were not statistical differences.5. Multiple linear regression model was used to assess the association of 25(OH)D3 with the MS individual components. The concentration of 25(OH)D3 showed strong association with the LDL(β=-12.839,P<0.001),SBP(β=-39.617,P<0.001),TG (r=-4.624,P=0.009),HDL(β= 12.089,P=0.014), and DBP(β=18.550,P=0.038).The regression equation is 25 (OH) D3=34.216-12.842 LDL-0.116 SBP-4.646 TG+12.06 HDL+0.089 DBP(F=8.860,P<0.001).Conclusions1. Vitamin D deficiency is common in the healthy people. The mean concentration of 25(OH)D3 in the health subjects who are from Jinan of Shandong Province and surrounding areas is 21.42±4.85ng/mL (95% confidence interval 20.46-22.37).2.The concentration of vitamin D in the patients with MS is significantly lower than the healthy subjects, and vitamin D deficiency is more prevalent in MS patients, compared with those who do not achieve the criteria for this syndrome3. In the MS group, we observe the concentration of 25(OH)D3 correlated negative with the waist circumference, FPG, TG, LDL-C, and uric acid. These indicate low 25(OH)D3 level is significantly associated with increased risk of having MS.