Serum xylosyltransferase activity in diabetic patients as a possible marker of reduced proteoglycan biosynthesis

Abstract

OBJECTIVE - Proteoglycan metabolism is altered in diabetic patients. The xylosyltrans-ferases (XTs) are the initial and rate-limiting enzymes in the biosynthesis of the glycosamino-glycan chains in proteoglycans. Here, we analyzed whether the changed proteoglycan metabolism leads to altered serum XT levels in diabetic patients. RESEARCH DESIGN AND METHODS- Serum XT activity was determined in 100 diabetic patients and 100 blood donors using a novel high-performance liquid chromatography electrospray ionization tandem mass spectrometry assay. RESULTS- Serum XT activities in male and female diabetic patients were significantly decreased compared with those in the corresponding normoglycemic control subjects (mean ± SD: male patients, 19.3 ± 4.44 mU/1; male nondiabetic control subjects, 26.6 ± 2.79 mU/1; female patients, 18.9 ± 3.14mU/l; female nondiabetic control subjects, 21.8 ± 3.74 mU/1; P< 0.0001). No significant differences were detected between patients with type 1 and type 2 diabetes. CONCLUSIONS - Our data show decreased XT activity in patients with diabetes, a disease that is accompanied by an altered proteoglycan biosynthesis. © 2008 by the American Diabetes Association.