Total cholesterol, HDL cholesterol, triglyceride, glycohaemoglobine and plasma glycoprotein levels were measured in 67 diabetic children and 40 nondiabetic ones. A dynamic study on C peptide secretion was also made in 28 diabetic patients. It was checked the fact that diabetic children showed normal whole cholesterol (172.1 +/- 32.1 mg/dl), HDL cholesterol (48.1 +/- 18.8 mg/dl) and triglyceride (58.3 +/- 26.8 mg/dl) levels, demonstrating no relationship with sex, age, length of diabetes, nor with the degree of metabolic control of disease, classified taking into account several clinical and biochemical indicators. C peptide concentration was found to be within normal levels in the whole group of patients under clinical remission phase of diabetes and also in 75% of children during the first 6 months of disease development. C peptide levels were higher in male than female diabetic children, showing an inverse relationship with duration of disease (r = -0.577, p less than 0.001) and with daily insulin requirements (r = -0.532, p less than 0.005). Discriminant analysis and multiple regression analysis results showed that the patients with a higher risk of bad control of diabetes were the older, those with a larger duration of disease, specially female, those with no remission phase of diabetes during clinical course of disease, and those showing bad motivation in relation to treatment.