Aim of this 1-yr open parallel study was to evaluate the efficacy of two regimens of intensive insulin treatment: continuous s.c. insulin infusion (CSII) and multiple daily insulin injection (MDI) treatment with lispro plus glargine in 48 Type 1 diabetic patients that had been treated with MDI (regular or lispro insulin before each meal plus NPH) for at least 1 yr. Twenty-four patients treated with CSII, receiving lispro at multiple basal infusion rates plus boluses at meal (CSII group), were compared to 24 patients, matched for age, duration of diabetes and metabolic control, treated with MDI with lispro at each meal combined with glargine (glargine group). In the CSII group, compared to traditional MDI treatment, there was a decrease in HbA1c (9.0 +/- 1.3% during traditional MDI vs 8.0 +/- 1.0% during CSII, p<0.001), severe hypoglycaemic episodes (0.42 vs 0.17 per patient/yr, p<0.05), insulin requirement (48 +/- 11.7 vs 35.9 +/- 8.5 U/day, p<0.001). In the glargine group, compared to MDI traditional treatment, there was a decrease in HbA1c (8.6 +/- 1.1 vs 7.9 +/- 1.2%, p<0.001) and severe hypoglycaemic episodes (0.46 vs 0.21 per patient/yr, p<0.05). No significant difference between the CSII group and the glargine group was present in the degree of improvement in HbA1c and severe hypoglycaemic episodes. However, in the CSII group there was a significantly greater reduction in mean amplitude of glycaemic excursions (MAGE) and insulin requirement than in the glargine group. In conclusion, despite a similar improvement in metabolic control, CSII improves blood glucose variability when compared to MDI with glargine as basal insulin.