An elevated serum sialic acid concentration has recently beenshown to be a potent cardiovascular risk factor in the general population. Because clinical proteinuria is associated with a high frequency of cardiovascular disease, and because microalbuminuria predicts the development of renal and cardiovascular disease in diabetes, we investigated whether serum sialic acid levels are increased in insulin-dependent diabetes mellitus (IDDM) patients with microalbuminuria or clinical proteinuria.
We studied 23 patients with IDDM who had a normal urinary albumin excretion rate, 23 patients who had microalbuminuria, and 23 patients with clinical proteinuria. The patients were matched for age, sex, duration of diabetes, GHb levels, and body mass index (BMI). Fasting blood samples were taken for measurement of sialic acid, cholesterol, triglyceride, creatinine, and GHb.
Serum sialic acid was significantly higher in the microalbuminuric patients compared with the normoalbuminuric group (mean ± SD: 1.93 ± 0.26 vs. 1.76 ± 0.27 mM, P < 0.01). Moreover, serum sialic acid was also significantly higher in the group with clinical proteinuria compared with the microalbuminuric patients (2.34 ± 0.24 vs. 1.93 ± 0.26 mM, P < 0.001). Serum sialic acid was not related independently to age, BMI, diabetes duration, GHb, blood pressure, serum cholesterol, triglyceride, or creatinine concentration in any of the diabetic groups.
These observations suggest that the serum sialic acid concentration is raised in IDDM patients with both microalbuminuria and clinicalproteinuria and may play a role as a cardiovascular risk factor or disease marker in these conditions.