| Objective:This study intends to measure the serum 25(OH)D level of patients with type 2diabetes,observe the islet function characteristics among different levels of serum25(OH)D groups,and preliminarily explore the effect of serum 25(OH)D level on islet function of patients with type 2 diabetes.Method:559 patients with type 2 diabetes were enrolled according to the study criteria.They were divided into quartile groups according to the measured serum 25-hydroxyvitamin D values.They were divided into Group A(140 cases),Group B(140cases),Group C(140 cases)and Group D(139 cases)according to the values from low to high.The age,sex,height,weight,and other general data of the patients were collected and body mass index(BMI)was calculated.Serum 25(OH)D level and fasting laboratory indexes such as glycosylated hemoglobin A1 c,plasma glucose,liver and kidney function,blood lipid,blood phosphorus and calcium were measured.75 g oral glucose tolerance test,insulin release test and C-peptide release test.The isletβcell function index(HOMA2-β)and insulin resistance index(Homa2-IR)were calculated.The area under the curve of glucose,insulin and C peptide(AUCglu,AUCins and auccp)was calculated OGTT 120 min after OGTT.The islet β cell function index(HOMA2-β)and insulin resistance index(Homa2-IR)were calculated.The area under the curve of glucose,insulin and c peptide(AUCglu,AUCins and auccp)was calculated OGTT 120 min after OGTT.The ratio of insulin increment to blood glucose increment(△I30/△G30)and C-peptide increment to blood glucose increment(△ CP30/△ G30)at OGTT 30 min were calculated.The ratio of area under insulin curve and blood glucose curve(AUCins/AUCglu)and the ratio of area under peptide curve and blood glucose curve(AUCcp/AUCglu)were calculated.To compare the general clinical data,biochemical indexes and islet function evaluation indexes of patients in each group,analyze the correlation between25(OH)D and islet function,and explore the influence of serum 25(OH)D level onislet function.One-way ANOVA was used to compare normal distribution data among groups,and LS-D method was used to compare every two groups.Non-parametric Kruskal-Wallis H test is used for comparison between groups of non-normal distribution data and pairwise comparison between groups.Chi-square test was used for counting data.Pearson and Spearman correlation analysis was used to calculate the correlation between 25(OH)D and each index,and multiple linear regression analysis was used to analyze the effect of 25(OH)D on islet function.Results:1.There were significant differences in gender and age among the four groups(P<0.001).The average age of patients in Q1 group was 64.05±9.05 years,which was significantly higher than that in other three groups(60.84±10.01 years,54.89± 11.05 years and 54.00±9.84 years).The proportion of female patients in Q1 group was61.4%,which was significantly higher than 45.0%,40.0% and 35.9% in other three groups.The mean serum 25(OH)D level of female patients(19.70±5.91ng/ml)was lower than that of male patients(21.50±5.51 ng/ml),P<0.001.2.The incidence rates of hypertension,coronary heart disease,cerebrovascular disease,diabetic peripheral vascular disease and diabetic peripheral neuropathy were significantly different among the four groups(P<0.05).The prevalence rates of patients in Q1 group were 64.3%,37.9%,22.9%,75.0% and 71.4% respectively,which were significantly higher than those in Q4 group(49.2%、10.7%、10.7%、56.8% and 57.6%).However,there was no difference in the incidence of diabetic nephropathy and diabetic retinopathy among the four groups(P>0.05).3.Hb A1 c of patients in Q1 group was 9.77±2.02%,which was significantly higher than 9.50±2.17% in Q2 group,9.34±2.13% in Q3 group and 8.99±2.16% in Q4 group.There were differences in HOMA2-IR among the four groups(P<0.001).△I30/△G30[0.19(0.12,0.34)] and△CP30/△G30[0.07(0.02,0.12)] in Q1 group were significantly lower than those in other three groups(P<0.001).The AUCcp/AUCglu[0.20(0.14,0.30)] in Q1 group was significantly lower than that in other three groups(P=0.037).There is no difference in FBG,Ca,p,BUN,SCr,UA and TC among the four groups(P>0.05).4.The 25(OH)D was negatively correlated with age,Hb A1 c,HOMA2-IR and AUCglu,and positively correlated with HOMA2-β,△I30/△G30,△CP30/△G30and AUCcp/AUCglu.5.Serum 25(OH)D in patients with T2 DM is a protective factor for early secretory function of islet β cells,and it is still a protective factor after adjusting for age,course of disease,BMI,Hb A1 c and FBG confounding factors(P<0.001).Conclusion:1.The deficiency of 25(OH)D is widespread in T2 DM patients,and the higher the age,the more obvious the deficiency of 25(OH)D.The deficiency of 25(OH)D in female patients is more obvious than that in male patients.2.The occurrence of diabetic peripheral vascular disease and diabetic peripheral neuropathy in T2 DM patients is related to the serum 25(OH)D level.The lower the25(OH)D level,the higher the incidence of these two complications,while diabetic nephropathy and diabetic retinopathy have nothing to do with the serum 25(OH)D level.The probability of T2 DM patients complicated with hypertension,coronary heart disease and cerebrovascular disease is also related to serum 25(OH)D level.The lower the 25(OH)D level,the higher the incidence of these three diseases.3.The level of serum 25(OH)D in T2 DM patients affects the function of islet βcells and is related to the control of blood sugar.25(OH)D may promote insulin secretion in T2 DM patients,especially early insulin secretion,and may improve insulin resistance in T2 DM patients.4.25(OH)D is related to islet function in T2 DM patients,and it is a protective factor of insulin secretion in T2 DM patients. |
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