Abstract Background: The aim of this study is to compare demographic/disease characteristics of users versus nonusers of a do-it-yourself (DIY) mobile technology system for diabetes (Nightscout), to describe its uses and personalization, and to evaluate associated changes in health behaviors and outcomes. Methods: A cross-sectional, household-level online survey was used. Of 1268 household respondents who were members of the CGM in the Cloud Facebook group, there were 1157 individuals with diabetes who provided information about Nightscout use. Results: The majority of individuals with diabetes in the household sample were 6–12 years old (followed by 18 years and above, and 13–17 years), non-Hispanic whites (90.2%), with type 1 diabetes (99.4%). The majority used an insulin pump (85.6%) and CGM (97.0%) and had private health insurance (83.8%). Nightscout use was more prevalent among children compared with adolescents and adults. Children used Nightscout for nighttime, school, sporting events, and travel; adults used it for nighttime, work, travel, and sporting events. Whereas the majority of adults viewed their own data without assistance from others, among pediatric users, a median of three individuals (range: 0–8) viewed Nightscout, with a median of three devices per viewer (range: 0–7). Individuals reported that after Nightscout adoption, they checked blood glucose values with a meter less often; bolused more frequently; gave more boluses without checking first with a blood glucose meter; and experienced significant improvements in HbA1c and quality of life. Conclusions: The Nightscout Project is a patient-driven mobile technology for health and may have beneficial effects on glycemic control and quality of life.