Frequency distribution of apoprotein(a) isoforms in patients with diabetes mellitus and healthy subjects.

AIM To determine the frequency distribution of apoprotein(a) isoforms in patients with insulin-dependent (IDDM) and non-insulin-dependent (NIDDM) diabetes mellitus and healthy subjects. METHOD We separated and visualized 5 apo(a) isoforms in 40 patients with IDDM (12 men aged 48.00-/+4.59 and 28 women aged 52.37-/+8.21), 65 patients with NIDDM (26 men aged 61.88-/+9.25 and 39 women aged 60.15-/+7.98), and 182 healthy subjects, using 3-15% gradient sodium dodecyl sulfate polyacrylamide gel electrophoresis, followed by immunoblotting. RESULTS The frequency distribution of apo(a) isoforms was very similar in patients with diabetes mellitus and the control group. Atherogenic low molecular weight (LMW) S1 apo(a) isoform was more frequent in patients with IDDM (7.5%) and NIDDM (6.15%) than in the control group (0.78%). LMW S1 apo(a) isoform in patients with IDDM (relative risk [RR], 6.86; 95% confidence interval [CI], 1.19-25.21; p<0.001) and patients with NIDDM (RR, 7.04; 95% CI, 1.40-35.40; p=0.0057) as well as high molecular weight >S4 apo(a) isoform in patients with NIDDM (RR, 2.39; 95% CI, 1.28-5.21; p=0.0067) significantly increased the risk for the development of atherosclerosis. Mean molecular weight of S3, S1, and B apo(a) isoforms was higher in patients with IDDM and NIDDM than in the healthy subjects carriers of the same isoforms, but this difference was not statistically significant. We estimated high inverse statistical correlation between apo(a) size (kDa) and plasma lipoprotein(a) concentration in all study groups, patients with IDDM (p<0.001), patients with NIDDM (p<0.001), and healthy subjects (p<0.01). CONCLUSION Not only the increased plasma Lp(a) levels, but also apoprotein(a) isoforms may play an important role as a risk factor for the development of atherosclerosis in patients with diabetes mellitus.