Measurement of sialic acid and acute phase reactant proteins in sera of patients with diabetic nephropathy.

Measurement of sialic acid and acute phase reactant (APR) proteins in sera of patients with diabetic nephropathy was performed. Twenty-six patients with non-insulin-dependent diabetes mellitus (NIDDM) were examined. The levels of sialic acid in sera, with or without treatment of neuraminidase, were measured by the thiobarbiturate method. The levels of alpha 1-antitrypsin (alpha 1-AT), alpha 1-acid glycoprotein (alpha 1-AG) or alpha 2-macroglobulin (alpha 2-MG) were measured by laser nephelometry. The levels of sialic acid or APR proteins in sera of patients with diabetic nephropathy were increased markedly. There was a significant correlation between the levels of sialic acid and those of alpha 1-AT in sera of patients with NIDDM. The mobility of alpha 1-AT in sera of patients with NIDDM treated with neuraminidase was decreased markedly in the immunofixation test. It is suggested that the increase of APR proteins in diabetic sera is mainly composed of sialic acid in patients with NIDDM with or without nephropathy.