Since complement component C3 is a major source of highly mannosylated glycans in plasma N-glycome, the observed change of this type of glycans could be a consequence of different C3 glycosylation pattern, as we herein report that C3 N-glycome is sensitive to T1D non-proliferative diabetic retinopathy. The gene discussed is C3; the disease is proliferative diabetic retinopathy.