To clarify the relationship between the increased PGRN and the development of diabetic microvascular complications, we further tested PGRN levels in patients with different stages of diabetic nephropathy and retinopathy; we found that serum PGRN levels did not differ distinctly between simple diabetes mellitus and microalbuminuric patients or between patients with simple diabetes mellitus and background retinopathy group. Here, GRN is linked to non-proliferative diabetic retinopathy.