Evaluation of serum glycated lipoprotein(a) levels in noninsulin-dependent diabetic patients

Objectives: Serum Lp(a) levels are generally considered unaffected by non-insulin-dependent diabetes mellitus (NIDDM). However, high Lp(a) concentrations as well as an increased rate of nonenzymatic glycation of proteins may be involved in degenerative diabetic complications. Design and Methods: We measured serum glycated Lp(a) levels in 17 NIDDM patients, as compared to 14 normoglycaemic controls. Glycated proteins were separated from nonglycated ones by boronate affinity chromatography, and specific proteins assayed by immunonephelometric methods in both fractions. Results: The percentage of glycated Lp(a) was 1.5 ± 0.4% (mean ± SD) in the control group, and was significantly higher in NIDDM patients: 4.3 ± 1.5% (p< 0.01). The basal level of Lp(a) glycation was lower than that of other proteins, particularly apo B (4.0 ± 0.7%). By contrast, the variations of glycated Lp(a) levels were of greater amplitude (+187%) than those of glycated apo B (+67%). Glycated Lp(a) values were significantly elevated in patients with micro and macrovascular complications in comparison with uncomplicated patients. Conclusions: These results suggest that glycated Lp(a) may be considered a potentially interesting parameter in the pathophysiology of diabetic vascular complications.