UMOD and diabetic kidney disease: Upon excluding this study, the heterogeneity was significantly decreased from moderate heterogeneity (I2 = 45%, p = 0.1) to low heterogeneity (I2 = 3%, p = 0.39), and the pooled results strengthened slightly (SMD: -0.38; 95% CI: -0.49, -0.27; p < 0.00001), and demonstrated that the low level of uromodulin is significantly associated with DKD compared to control.