Glycosylated serum proteins in diabetic patients and their relation to metabolic parameters.

Glycosylated plasma proteins (GSP) and some metabolic parameters (plasma glucose profile, urine glucose excretion, glycosylated hemoglobin, cholesterol, triglycerides) were evaluated in 70 diabetic and 70 normal subjects. Of the late diabetic complications, retinopathy, nephropathy and somatic neuropathy were evaluated. Proliferative retinopathy was observed in 41 of the 70 diabetics studied. No retinopathy or background retinopathy was observed in 29 diabetics. Nephropathy was diagnosed in 39 patients and somatic neuropathy in 44 patients; 26 diabetic subjects had no complications. GSP levels were 0.82 +/- 0.03 nmolHMF/mg prot in diabetics and 0.43 +/- 0.02 nmolHMF/mg prot in controls. GSP levels were positively correlated with metabolic parameters evaluated the same day and 14 days before. A positive correlation between GSP and triglycerides was seen for the first time. The patients with retinopathy showed levels of GSP significantly higher (p less than 0.001) in respect to patients with background retinopathy or absence of it (0.91 +/- 0.03 vs 0.74 +/- 0.04 nmolHMF/mg prot). GSP were significantly higher in the patients with somatic neuropathy (0.93 +/- 0.02 nmolHMF/mg prot) (p less than 0.001) than in the subjects without neuropathy (0.72 +/- 0.04 nmolHMF/mg prot). GSP levels were 0.92 +/- 0.03 nmolHMF/mg prot in diabetics with proteinuria and 0.75 +/- 0.04 nmolHMF/mg prot in diabetics without proteinuria (p less than 0.001). These results confirm the importance of GSP determination as another parameter of glycemic control and particularly as an index of the overall protein glycosylation processes.