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 constituents 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, A1 and B) and glycaemic (HbA1c, fasting blood glucose) parameters in 40 patients with type 1 diabetes mellitus and in 103 age- and sex-matched 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 apolipoprotein A, A1 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 apoB (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.(ABSTRACT TRUNCATED AT 250 WORDS)