High Cystatin C And Low25-OH-Vitamin D Levels Are Associated With Retinopathy In Type2Diabetes Patients

ObjectiveDiabetic retinopathy is the leading cause of new cases of blindness among adults. CystatinC and vitamin D were shown involved in the retinal neovascularization and inflammationin diabetes. We investigated the relationship between cystatin C, vitamin D deficiency(VDD) and diabetic retinopathy (DR), and identified the potential predicting value ofcystatin C and VDD for DR.MethodsA total of1541and954patients with type2diabetes were recruited, undertaken fundusoculi photographs, and their clinical characteristics and biochemical parameters weredetected and compared. They were divided into three groups according to their fundusoculi results: no diabetic retinopathy (NDR; n=625,40.56%); non-sight-threateningdiabetic retinopathy (NSTDR; n=568,36.86%); and sight-threatening diabetic retinopathy(STDR; n=348,22.58%). All the patients were also divided into quartiles with respect totheir cystatin C concentrations (≤0.8mg/L as reference,0.9–1.0mg/L,1.1–1.2mg/L,≥1.3mg/L) and25-OH-VitD levels, respectively. VDD was defined as serum circulating25-hydroxyitamin D [25(OH)D] level <20ng/mL.Results:1. There were significant differences and an ascending trend in prevalence of DR,NSTDR and STDR among cystatin C quartiles. The serum level of cystatin C in STDRgroup was higher than that of NDR and NSTDR groups (all p <0.05).2. A significant positive association was clearly observed between cystatin C and DR inhighest quartile compared to lowest quartile (referent) after adjusted for potentialconfounding factors. Multiple logistic regression analysis further revealed that theindependent risk factors for DR included cystatin C, HbA1c and diabetes duration (all p <0.05). 3. The receiver operating characteristic curve (ROC) analysis indicated that cystatin Chigher than1.25mg/L predicted10-fold increased risk of severe retinopathy [odds ratio(OR)11.360,95%confidence interval (CI)7.659-16.851, p<0.001].4. The prevalence of individuals with VDD increased with severity of retinopathy (NDR,15.10%; NSTDR,23.14%; STDR,25.29%; p <0.01).The Chi-square test between groupsrevealed the prevalence of DR, NSTDR and STDR in patients with VDD was significantlyhigher than those without VDD (all p <0.01).5. After adjusting for potential confounders in the multivariable model, VDD wasassociated with increased risk of DR. Multiple logistical regression analysis revealed thatVDD, diabetes duration, Waist:hip ratio (WHR), systolic blood pressure (SBP) wereindependent risk factors for DR (all p <0.05).6. ROC analysis demonstrated that25(OH)D level <11.31ng/mL hinted near doubled riskof retinopathy (OR1.878,95%CI1.350–2.613).Conclusions:1. High serum cystatin C and low25(OH)D levels are independent risk factors for DR.2. High cystatin C level predicts the10times increasing morbidity of sight-threateningdiabetic retinopathy.3. The incidence of DR nearly doubles when serum25(OH)D level is less than11.31ng/mL.