OBJECTIVES:  To evaluate the metabolic effect of adding continuous glucose monitoring (CGM) to insulin pump therapy and the impact on Health Related Quality of Life (HRQOL), Treatment Satisfaction (TS). METHODS: Eighty-one adults & seventy-two children with Type 1 diabetes participated in a multicenter, randomized, controlled, cross-over study.  Following a one month run-in period, subjects were randomized to CGM Sensor-ON or Sensor-OFF arms for six months, following a four month wash-out period subjects crossed over to the other treatment arm for six additional months. Diabetes Treatment Satisfaction Questionnaire (status version; DTSQs) in adults and Pediatric Quality of Life Inventory (PedsQL) in children were collected at baseline and end of each treatment period.  Analyses were controlled for baseline values, and there was no sequence effect observed in either age group. RESULTS: Sensor use significantly improved glycemic control resulting in an HbA1c reduction of  -0.43% in the intention to treat population (ITT). Adult TS improved significantly (p<0.012) compared to baseline, favoring Sensor-ON in ITT.  There was no significant difference in the perceived frequency of hypo- or hyperglycemia with CGM.  Sensor use was positively associated with TS (p=0.027) in the per-protocol group. There was no significant difference in children’s perceived overall HRQOL between Sensor-ON and Sensor-OFF.  Individual items of the PedsQL and DTSQs were analyzed separately. CONCLUSIONS: Adding CGM  to pump therapy  significantly improves metabolic control.  CGM use significantly improves treatment satisfaction in adults, and had no impact on the overall HRQOL in children.  Increased usage of the sensor was associated with an increase of the TS score in adults.