Non enzymatic glycosylation of IgG and their urinary excretion in patients with diabetic nephropathy

Diabetic nephropathy is a major cause of end stage renal disease. Increased excretion of albumin has widely been recognized as an early manifestation of diabetic nephropathy particularly in subjects with diabetes mellitus. However, certain other proteins besides albumin may be excreted in high amount during early phase of diabetic nephropathy. The serum and urinary IgG, Glycosylated hemoglobin, fructosamine and glycosylated IgG were evaluated in the present study. Thirty-two patients of Type 2 Diabetes without any complications, thirty-one patients of Type 2 Diabetes with nephropathy, twenty-six patients of non-diabetic nephropathy and forty normal healthy individuals were enrolled in this study. Subjects were grouped based on their serum creatinine level. Serum IgG, glycosylation of IgG and urinary IgG excretion were increased significantly in diabetic patients compared to healthy controls, which were further increased significantly in chronic renal failure patients with respect to the clinical stage of nephropathy. A positive correlation was observed between glycosylation of IgG and IgG excretion (R=0.5995, 0.7114 respectively) in diabetic patients without any complications and diabetic nephropathy patients only, suggesting a significant role of IgG glycosylation in the vascular clearances of IgG during diabetic nephropathy. © 2009 Association of Clinical Biochemists of India.