UNLABELLED: In a population of 106 young type I diabetic patients, we evaluated whether a relationship exists between lipoprotein (Lp)(a) or apolipoproteins and the degree of metabolic control (HbA1c, fructosamine) or the subclinical complications. The patients were subdivided according to puberty and to the presence or not of subclinical complications (no complications [n = 32]; retinopathy at fluorescein angiography [n = 28]; neuropathy diagnosed by reduced peroneal motor nerve conduction velocity [n = 30]; nephropathy determined by presence of micro-albuminuria [n = 15]. Lp(a) concentrations were not significantly increased in the whole group of diabetic patients. There was no difference between girls and boys, nor between the prepubertal children and the others. There were no significant correlations between the markers of metabolic control and Lp(a). Nevertheless, if the diabetic patients were divided into two groups according to the levels of HbA1c (<7.6 or > or = 6% Hb), Lp(a) tends to be higher in the poorly controlled, but not to any significant degree. On the other hand, significant increases of total cholesterol, triglycerides, low density lipoprotein cholesterol and apolipoprotein B levels were observed in poorly controlled patients. Lp(a) concentrations were significantly lower in patients with subclinical neuropathy or nephropathy than in patients without these complications, but not in patients with retinopathy versus no retinopathy. These results are confirmed by categorical analysis (i.e. Lp(a) < or = 30 vs > 30 mg/dl). CONCLUSION: Lp(a) levels are not significantly increased in poorly controlled insulin-dependent diabetes mellitus patients. High controlled insulin-dependent diabetes mellitus patients. High levels of Lp(a), in young diabetic patients, are not markers for subclinical complications (retinopathy, neuropathy and nephropathy). On the contrary, low Lp(a) levels were found in subjects with subclinical neuropathy or nephropathy.