Elevation of Glycoprotein Fucose in Diabetes Mellitus

The pattern of serum protein-bound carbohydrate elevation in diabetes mellitus has been investigated. Cation exchange chromatography on individual sera was followed by serial separation technics on diabetic and control serum pools. The protein-bound hexose elevation could be accounted for by elevated levels of several serum glycoproteins, especially haptoglobin, α₁-acid glycoprotein, and α₁-antitrypsin. In contrast, only a small portion of the fucose increase could be accounted for by the elevated glycoprotein levels. Fractionation of the serum proteins revealed the fucose increase to be produced by more than one glycoprotein. When ion exchange and gel filtration chromatography were combined to produce elution areas in which only one glycoprotein could be recognized immunologically, a pattern emerged. Three glycoproteins, whose major common source is the liver parenchymal cell, had increased fucose levels, while three immune globulins, not produced by this cell, had normal fucose levels. The demonstration of increased fucose content only in glycoproteins formed by liver cells suggests a metabolic basis for increased serum protein-bound fucose, and a mechanism relating increased hepatic gluconeogenesis and associated cytoplasmic oxidation-reduction changes to increased fucose synthesis is postulated.