Changes in glycosylated proteins in long-term complications of diabetes mellitus.

Increased glycosylation of various proteins in diabetic patients has been reported by many authors. In the present study, the extent of non-enzymatic glycosylation in diabetic patients with or without chronic complications was investigated. Eighty-five diabetic patients were studied, 20 were without any clinical evidence of chronic complications while the remainder were suffering from cataract (n = 18), retinopathy (n = 16), peripheral neuropathy (n = 16) and cardiovascular complications like angina pectoris, myocardial infarction and hypertension (n = 15). All patients were selected on clinical grounds. Fifteen apparently healthy subjects of similar age and weight were studied as control subjects. Fasting plasma glucose was increased in all diabetic patients and correlated significantly with glycosylated hemoglobin, glycosylated plasma protein and serum fructosamine concentrations. There was no significant difference between diabetic patients with or without chronic complications in the levels of fasting plasma glucose, glycosylated plasma proteins, glycosylated hemoglobin, serum fructosamine, mucoprotein, hexosamine, sialic acid and fucose. Alpha-2 globulin fraction was increased in both uncomplicated and complicated diabetic patients and albumin was found to be decreased in patients with cataract, peripheral neuropathy and cardiovascular diseases. Alpha-1 and beta globulins were significantly decreased in patients with cardiovascular diseases and retinopathy respectively while gamma globulin was increased in retinopathy patients. In uncomplicated diabetic patients alpha-1 glycoprotein was decreased and gamma glycoprotein was increased. In diabetic patients with retinopathy, alpha-1 glycoprotein was elevated significantly while beta glycoprotein was decreased.