APOLIPOPROTEIN(A) LEVELS IN PATIENTS WITH TYPE-1 DIABETES-MELLITUS ARE UNRELATED TO METABOLIC CONTROL OR VASCULAR-DISEASE

Increased serum levels of lipoprotein (a) have been found to be an independent risk factor for coronary heart disease. The major protein constitents of lipoprotein (a) are apolipoprotein B 100 und apolipoprotein (a) (apo(a)). We determined the serum levels of apo(a) and several lipid (cholesterol, HDL- and LDL-cholesterol, triglycerides, apolipoproteins A, A 1 and B) and glycaemic (HbA1c, fasting blood glucose) parameters in 40 patients with type 1 diabetes mellitus and in 103 age- and sex-matached control subjects. The median serum levels of apo(a) were significantly increased in the type 1 diabetic patients (142.7 vs. 80,0 U/L; P = 0.03), whilst HDL, LDL-cholesterol, and apo-lipoprotein A, A 1 and B levels were lower (P < 0.01). No significant correlation was found between parameters of metabolic control and apo(a) levels. After subdivision of the diabetic patients according to different stages of diabetic nephropathy (DN), determined by urinary albumin excretion, significant relationships were found between DN and triglycerides (P = 0.04), LDL (P = 0.03) and apolipoprotein B (P = 0.008, Kruskal-Wallis test) levels. Apo(a) levels were significantly higher than normal values in patients without DN (P < 0.05), but unrelated to the degree of DN. Patients with diabetic macroangiopathy had significant higher levels of cholesterol (P = 0.0001), triglycerides (P = 0.026), LDL (P = 0.0003), and apo B (P = 0.002) than patients without. Apo(a) levels were unrelated to diabetic macroangiopathy. The significantly elevated levels of apo(a) even in patients without DN or macroangiopathy are noteworthy. Although the elevated apo(a) levels might be an additional explanation for the elevated cardiovascular risk of type 1 diabetic patients, the great variability of this parameter could be explained by genetic determination.