GRN and diabetic kidney disease: 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.