Associations between a high daily insulin dose and cardiovascular risk factors, including those of the insulin-resistance syndrome, were studied in 479 Type 1 diabetic children 6 to 18 years of age. Insulin dose increased over the first two years after diagnosis of diabetes (p = 0.0001) and was significantly higher in girls (p = 0.01). For those children with diabetes duration of more than 2 years, the insulin requirement increased up to 13-14 years of age (p < 0.05) and was higher in pubertal than pre-pubertal children (p < 0.05). For girls, the requirement was higher in puberty than in post-puberty (p < 0.05) and increased with diabetes duration (p < 0.05). Triglyceride concentrations were associated positively and significantly with the insulin dose of both boys and girls, after adjustment for age, pubertal stage, diabetes duration, and metabolic control (fructosamine levels). No other consistent associations were found between insulin dose and other cardiovascular risk factors: body mass index, central adiposity, arterial blood pressures, serum total cholesterol, apoA1, apoB, Lp(a), uric acid, or urinary albumin excretion. Parental obesity, hypertension and diabetes were not related to the insulin dose of children. The results did not differ when the population was limited to the 375 children with diabetes duration of more than 2 years. It is concluded that in these Type 1 diabetic children the insulin dose for a given level of metabolic control (our surrogate measure of insulin resistance) was related to a single cardiovascular risk factor: triglyceride concentrations.