GSTM1 and diabetic kidney disease: Classes B and C showed significantly higher rates of male sex, diabetic nephropathy, smoking, hypertension, and cardiovascular complications, and a greater amount of proteinuria than Class A. Baseline low Hb levels and massive proteinuria at 12 weeks were significant predictors of ERI trajectories for both Classes B and C. Male sex, iron supplementation at baseline, and Cr level at 12 weeks were significant predictors for Class B ERI trajectories.