IGFBP1 and type 1 diabetes mellitus: Compared with T1D patients without DN, however, the IGFBP-1 serum levels in T1D patients with DN were significantly increased in both male (52 μg/L versus 28 μg/l, P = 0.021, Figure 3C) and female patients (71 μg/L versus 33 μg/L; P = 0.003; Figure 3D).