GDF15 and diabetic kidney disease: In multivariate logistic regression analysis (Supplementary Table S4), increasing GDF-15 turned out to be a statistically significant independent predictor of the prevalence of diabetic kidney disease (OR: 1.07; 95% CI: 1.01–1.12; p = 0.015) after an adjustment for T1DM duration, HbA1c, BMI, and smoking (p = 0.0002).