DPP4 and chronic kidney disease: Serum DPP-4 levels were markedly decreased following linagliptin treatment, with the largest differences seen at 8 weeks (26.4 ± 1.8 vs. 2.8 ± 1.8 for CKD and CKD-Lina 8 weeks, respectively; p < 0.01; Fig. 3).