Fig. 2

Effect of linagliptin treatment on active GLP-1, active GIP and active SDF-1a in serum and brain. Serum levels of active GLP-1 (a), active GIP (b) and active SDF-1α (c) after prolonged linagliptin treatment. Levels of active GLP-1 (d), active GIP (e) and active SDF-1α (f) in the brain after prolonged linagliptin treatment. Unpaired t test with Welch’s correction, mean ± SD. **, ***and **** denote p < 0.01, p < 0.001 and 0.0001 respectively