We examined quality-of-life (QOL) of patients with a prospective comparison of multiple daily insulin injections therapy (16 patients in MDI group) and continuous subcutaneous insulin infusion therapy (12 patients in CSII group) using insulin lispro (LP), which was switched from short-acting insulin on the basis of a questionnaire about insulin-therapy-related QOL measure (ITR-QOL). The overall score of ITR-QOL before using LP in the CSII group was significantly higher (P<0.02) than the MDI group. In four subscales of ITR-QOL, the scores of social and daily activities and of therapy-related feelings in the CSII group were significantly higher (P<0.02) than those in the MDI group, respectively, while there was no significant difference in the score of physical function between the two groups. Three months after using LP, the score of daily activities in the MDI group was significantly higher (P<0.02) than that before using LP, while there were no significant differences in other scores of the two groups. There were no significant differences in HbA1c between two groups before and after using LP. The frequency of hypoglycemic events in the MDI group before using LP was higher than that in the CSII group and decreased after using LP. These results show that QOL of patients treated by CSII is superior to that treated by MDI and demonstrate that insulin lispro has a more beneficial effect on daily activities in patients treated by MDI than short-acting insulin.