The aim of this study was to develop a questionnaire that measures the impact of insulin therapy on patients' health-related quality of life QOL.The insulin therapy-related QOL measure (ITR-QOL) questionnaire includes 23 items.Factor analysis showed 4 subscales: social activities, daily activities, physical function, and therepy associated feelings with insulin therapy.Both test-retest reliability and internal consistency of the ITR-QOL questionnare were high.Content validity was confirmed by several diabetologists.In concurrent validity, ITRQOL scores were related significantly to DTSQ and W-BQ 12 scores, representative questionnaires on diabetes.Taking the above factors into consideration, we concluded that the ITR-QOL questionire is valid as the measurement of QOL in insulin-treated patients.