Serum zonulin levels in type 2 diabetes patients with diabetic kidney disease.

Abstract

Recent data have shown that diabetic kidney disease (DKD) is associated with abnormal gut microbiota composition. Zonulin is a physiological tight junction modulator and an intestinal permeability marker. In this study we aimed to investigate serum levels of zonulin and interleukin 6 (IL-6) in patients with type 2 diabetes mellitus (T2DM) and different levels of albuminuria. Ninety patients with T2DM and 30 healthy controls (HC) aged between 18 and 65 years were enrolled in the study. T2DM patients were divided into three groups as patients with normoalbuminuria (n = 30), microalbuminuria (n = 30), and macroalbuminuria (n = 30). Serum zonulin and IL-6 levels were measured by ELISA method. There was no significant difference between groups in terms of age, gender, serum ALT, LDL-C, HDL-C, and zonulin levels (p > 0.05). Significant differences between groups were present for the duration of diabetes (p < 0.001), body mass index (p < 0.001), fasting blood glucose (p < 0.001), creatinine (p < 0.001), uric acid (p = 0.037), triglyceride (p = 0.003), total cholesterol (p < 0.001), glycated haemoglobin (p < 0.001), and IL-6 (p < 0.001) levels. IL-6 levels were significantly increased in the microalbuminuria and macroalbuminuria groups compared to the HC group, but no significant difference was determined between the HC and normoalbuminuria group. In patients with diabetic kidney disease, a significant positive correlation was found between zonulin with IL-6 and proteinuria (rho = 0.296, p = 0.008; rho = 0.190, p < 0.047, respectively). The serum IL-6 level was positively correlated with microalbuminuria and proteinuria (rho = 0.451, p < 0.001; rho = 0.425, p < 0.001, respectively). We suggest that the serum zonulin level is not a promising biomarker to assess the severity of DKD in patients with long-standing T2DM.