25-Hydroxyvitamin D Is Associated with Islet Homeostasis in Type-2 Diabetic Patients with Abdominal Obesity

Objective Isletαcells input is essential for insulin secretion fromβcells.The present study aims to investigate the association between 25-hydroxyvitamin D[25(OH)D]and islet function homeostasis in type-2 diabetes(T2D)patients.Methods A total of 4670 T2D patients from seven communities in Shanghai,China were enrolled.The anthropometric indices,biochemical parameters,serum 25(OH)D,and islet function[including C-peptide(C-p)and glucagon]were measured.Results The fasting plasma glucose(FPG),glycated hemoglobin(HbA1c),glucagon,and C-p levels exhibited a significantly decreasing trend in T2D patients as the 25(OH)D levels increased.Next,the population was divided into two groups:abdominal obesity and non-abdominal obesity groups.After adjustment,the 25(OH)D level was found to be associated with HbA1c,glucagon,and homeostasis model assessment ofβ(HOMA-β)in the non-abdominal obesity group.There was a significant relationship between 25(OH)D and HbA1c,glucagon,HOMA-IR,baseline insulin or C-p in the abdominal obesity group.In the abdominal obesity group,the ordinary least squares(OLS)regression and quantile regression revealed that 25(OH)D was obviously associated with glucagon and fasting C-p levels.In the abdominal obesity group,the moderate analysis revealed a significant interaction effect of 25(OH)D and glucagon on C-p(P=0.0124).Furthermore,the conditional indirect effect of 25(OH)D on the glucagon/C-p ratio was significantly lower at 1 standard deviation(SD)below the mean(P=0.0002),and lower at the mean of the course of diabetes(P=0.0007).Conclusion 25(OH)D was found to be negatively correlated to glucagon and C-p in T2D patients with abdominal obesity.The 25(OH)D influenced C-p in part by influencing glucagon.The effect of 25(OH)D on the glucagon/C-p ratio in T2D patients with abdominal obesity,in terms of islet homeostasis,is influenced by the course of diabetes.

Association between sex hormone-binding globulin and kidney function in men: results from the SPECT-China study

Background::The association between sex hormone-binding globulin(SHBG)and renal function has rarely been reported in men.We aimed to investigate the above association in a community-based Chinese population.Methods::A total of 5027 men were included from the survey on prevalence for metabolic diseases and risk factors,which is a population-based study conducted from 2014 to 2016 in Eastern China.The estimated glomerular filtration rate(eGFR)was calculated according to the chronic kidney disease Epidemiology Collaboration equation.Low eGFR was defined as eGFR<60 mL·min-1·1.73 m-2.Results::After adjusting for age,smoking,metabolic factors,and testosterone,through increasing quartiles of SHBG,a significantly positive association between SHBG quartiles and eGFR was detected in men(Q1 vs.Q4,β-2.53,95%confidence interval-3.89,-1.17,Ptrend<0.001).Compared with the highest quartile of SHBG,SHBG in the lowest quartile was associated with 96%higher odds of low eGFR(odds ratio 1.96,95%confidence interval 1.10,3.48)in the model after full adjustment.According to the stratified analyses,the associations between a 1-standard deviation increase in serum SHBG and the prevalence of low eGFR were significant in men aged≥60 years old,waist circumference<90 cm,diabetes(no),hypertension(yes),dyslipidemia(no),and nonalcoholic fatty liver disease(no).Conclusions::Lower serum SHBG levels were significantly associated with lower eGFR and a higher prevalence of low eGFR in Chinese men independent of demographics,lifestyle,metabolic-related risk factors,and testosterone.Large prospective cohort and basic mechanistic studies are warranted in the future.