ANPEP and type 1 diabetes mellitus: In the T1DM group, the concentrations of the APN protein were 1.58±0.01 ng/mg in the retina and 2.13±0.03 ng/mg in the RPE-choroid, whereas in the control group, the concentrations were 1.46±0.01 ng/mg in the retina and 1.69±0.04 ng/mg in the RPE-choroid.