Endocrine Abstracts

JOINT363

Sialic acids are the carbohydrate part of glycoproteins presented in the conjugate form on the outer surface of membranes as membrane receptor. They are components of insulin receptors, interferon and serotonin, as well as of various circulation hormones, transporting proteins, lipoproteins, mucopolysaccharides and various exudates. The data on the concentrations of circulation sialic acids in diabetes mellitus (DM) are contradictory. The work was initiated to study concentrations of sialic acids the blood serum of patients with type 1 and type 2 DM.

Materials and methods: Twenty two patients with type 1 DM and 28 patients with type 2 DM aged from 26 to 65 were examined. The control group included 10 healthy persons of the matching age. Periodate-resorcinol method was used to measure concentrations of sialic acids. HbA1c was measured using enzyme-linked immunosorbent assay.

Results and discussion: Concentrations of the serum sialic acids in DM were found significantly increased, while those in erythrocytes and leucocytes were reduced. Our findings demonstrated that the serum sialic acid concentrations were increased in both DM types, as compared to the control ones (P<0.05). In type 1 DM, mean level was 291.7±42.9mg%. Sialic acids were significantly higher in patients with type 2 DM than those in healthy persons (174.5±27.0mg% vs 145.0±10.9mg%). Significant differences were observed in comparison of sialic acid concentrations between two groups of the diabetics (P<0.05). Mean HbA1c was higher in patients with type 1 DM than the one in the controls (6.7±1.9% vs 5.4±0.8%). Mean HbA1c in patients with type 1 DM was 7.8±1.5%. Sialic acids are known to be responsible for the formation of various isoforms of transferrin and regarded as a marker of microvascular complications in type 2 DM. Hyperglycemia results in the increase on non-enzymatic glycosylation of many proteins and in the formation of glycation end products. Non-enzymatic glycosylation changes properties and functions of some proteins. The changes in the glycosylation in DM were found by many authors. Most glycosylated proteins add the remains of sialic acids in their carbohydrate chains. The increased sialic acid concentrations may be caused by the generalized cell endothelial dysfunction either by the washout of glycoproteins containing sialic acids from cells into circulation or by the cytokine-mediated acute phase response. Thus, in association with other laboratory data determination of sialic acids may be used for assessment of severity of the disease and the depth of pathological process, as well as for differential diagnosis.